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  • richardmitnick 11:21 am on January 7, 2018 Permalink | Reply
    Tags: , , , , , Hyperspectral imagery, NASA Earth Science, NASA earth science needs a $350 million mission line, NASEM-National Academies of Sciences Engineering and Medicine, National Academies advise,   

    From Science: “NASA earth science needs a $350 million mission line, National Academies advise” 

    ScienceMag
    Science Magazine

    Jan. 5, 2018
    Paul Voosen

    1
    Successors to the Gravity Recovery and Climate Experiment, which monitored declining ice sheets and underground water, are a top priority for NASA earth science. NASA.

    NASA’s earth science division should create a new, medium-size $350 million mission line that is open to competition, according to a new report out today from the National Academies of Sciences, Engineering, and Medicine (NASEM) that lays out the agency’s earth science priorities in a so-called decadal survey, a consensus wish list for U.S. earth scientists. In addition to the call for the new mission line, the report recommends that five larger flagship missions be launched in the coming decade.

    Over the past decade, thanks to an infusion of climate-focused spending from the administration of former President Barack Obama, NASA’s budget for satellite-based observation of Earth grew to $1.9 billion last year, the largest of NASA’s four science divisions. “We’re not at the bottom of some pit like we were before,” says Bill Gail, chief technology officer at the Global Weather Corporation in Boulder, Colorado, and co-chair of the committee that wrote the report, titled Thriving on Our Changing Planet.

    But assuming the earth science budget now remains flat—far from a sure bet with the administration of President Donald Trump, which has been leery of climate research—NASA will have tough choices to make on future missions. “The simple fact is there’s not enough money to do what we want to do,” says Waleed Abdalati, director of the Cooperative Institute for Research in Environmental Sciences at University of Colorado in Boulder, and co-chair of the committee. Abdalati hopes that the new competitive mission line, along with a slim list of five flagship missions, will keep the earth science division within reasonable budgetary bounds.

    In 2007, when NASEM released its first earth science decadal survey, it prioritized 15 explicitly defined missions, many already tied to NASA centers. The new report recommends different types of observations without naming particular missions—although the correspondence to specific mission plans is clear in some cases. The recommendations take into account existing and planned satellites, such as a new line of Sentinel satellites from the European Space Agency. The survey aims to provide continuity on some valued measurements, and plot where the United States can fill potential gaps.

    The first priority observation recommended for flight, with a cost cap of $650 million, would target changes on Earth’s surface, likely with imagery across a wide range of wavelengths. The technique, called hyperspectral imagery, would advance on pioneering observations from Hyperion, a satellite instrument that was decommissioned last year. The recommendation is likely a shot in the arm for the Hyperspectral Infrared Imager (HyspIRI), a mission from NASA’s Jet Propulsion Lab in Pasadena, California, that was an uncompleted mission recommended by the last decadal.

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    NASA Hyperspectral Infrared Imager (HyspIRI)

    The other two largest investments, each cost capped at $800 million, would target clouds and atmospheric particles called aerosols. Aerosols and clouds are the two biggest drivers of uncertainty when it comes to the speed of human-driven global warming. The missions could end up being successors to the CloudSat and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellites. Like the existing pair, the panel envisions the missions launched in close succession to take advantage of overlapped observations. The recommendation for two separate missions could complicate the future of an expensive proposed mission, called Aerosol/Clouds/Ecosystems, out of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, that would have combined these instruments on the same satellite.

    NASA CALIPSO

    The final two priority observations are a $300 million successor to the recently ended Gravity Recovery and Climate Experiment (GRACE) and its successor satellite, expected to be launched early this year, and a $500 million satellite that would target tiny movements in the surface of Earth using radar techniques.

    NASA/DLR Grace

    Beyond these top priorities, the report names seven observations that should compete against one another in a new line of missions, called Earth System Explorer. NASA’s earth science has featured little competition in recent years, unlike the agency’s other science divisions. Within planetary science, for instance, NASA has two competitive lines, called Discovery and New Frontiers. With each mission capped at $350 million, the panel envisions explorer projects taking less than 4 years to develop, with the agency selecting three missions from among the seven candidates for flight this next decade.

    The potential observations for the explorer line are: atmospheric winds; greenhouse gases, providing potential continuity with the Orbiting Carbon Observatories; ice elevation, which would continue measurements of the ice sheets from IceSat-2, launching late this year; ocean surface winds; ozone and trace gases; snow depth and amount; and land ecosystems. The report is not prescriptive in how these measurements should be made, Abdalati adds. These observations could come from single satellites or constellations of smaller satellites—whatever combines the best mix of science and cost.

    The panel hopes that competition, and withholding specific mission recommendations, could help cure some of the cost inflation that came after the last survey, when missions were assigned to NASA centers and quickly saw their costs double in development. It was one of the mistakes of the last decadal, says Berrien Moore, the vice president of weather and climate programs at the University of Oklahoma in Norman and co-lead of the 2007 decadal. “The assignment of missions didn’t have the rigor that a competitive environment enforces,” he says.

    Earth science in space involves a constant tension between exploring new scientific terrain and continuing existing observations, which sometimes need to last for decades to provide useful information about climate change. To help address this problem, the panel recommends another new competitive line, called Venture-Continuity, which would allow scientists to propose ways of continuing observations at lower cost. The panel foresees selecting two such missions next decade, each capped at $150 million.

    Although the panel does not sound alarms like it did a decade ago, all of its recommendations are contingent on budgets rising with inflation. In its budget proposal last year, the Trump administration sought to boost planetary science and cut earth science. In particular, it plotted to kill four missions: the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite; the Orbiting Carbon Observatory-3 and the Climate Absolute Radiance and Refractivity Observatory Pathfinder, both set to be mounted on the space station; and an Earth-facing camera on the Deep Space Climate Observatory. It remains to be seen whether those cuts can make it through Congress. Moore hopes Senate opposition makes the cuts unlikely, and thinks that both planetary and earth science will thrive. “I wouldn’t be surprised to see both boats rise,” he says.

    Of course, the report’s influence depends on NASA’s response. The Obama administration pushed for a climate-focused architecture that did not hew precisely to the 2007 decadal, and the George W. Bush administration’s last NASA administrator, Mike Griffin, was hostile to their findings, Moore says. Trump’s nominee, Representative Jim Bridenstine (R–OK), has publically pledged to follow the decadal, however. He will likely face questioning on the decadal from the Senate—assuming he is renominated for the post and confirmed.

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  • richardmitnick 11:37 am on January 4, 2018 Permalink | Reply
    Tags: , , MLS-Microwave Limb Sounder, NASA - First Direct Proof of Ozone Hole Recovery Due to Chemicals Ban, NASA Aura satellite, NASA Earth Science   

    From NASA Earth Sciences: “NASA Study: First Direct Proof of Ozone Hole Recovery Due to Chemicals Ban” 

    NASA Earth Sciences

    Jan. 4, 2018
    Samson Reiny
    samson.k.reiny@nasa.gov
    NASA’s Earth Science News Team

    For the first time, scientists have shown through direct satellite observations of the ozone hole that levels of ozone-destroying chlorine are declining, resulting in less ozone depletion.


    Using measurements from NASA’s Aura satellite, scientists studied chlorine within the Antarctic ozone hole over the last several years, watching as the amount slowly decreased.
    Credits: NASA’s Goddard Space Flight Center/Katy Mersmann

    Measurements show that the decline in chlorine, resulting from an international ban on chlorine-containing manmade chemicals called chlorofluorocarbons (CFCs), has resulted in about 20 percent less ozone depletion during the Antarctic winter than there was in 2005 — the first year that measurements of chlorine and ozone during the Antarctic winter were made by NASA’s Aura satellite.

    “We see very clearly that chlorine from CFCs is going down in the ozone hole, and that less ozone depletion is occurring because of it,” said lead author Susan Strahan, an atmospheric scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    CFCs are long-lived chemical compounds that eventually rise into the stratosphere, where they are broken apart by the Sun’s ultraviolet radiation, releasing chlorine atoms that go on to destroy ozone molecules. Stratospheric ozone protects life on the planet by absorbing potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and damage plant life.

    Two years after the discovery of the Antarctic ozone hole in 1985, nations of the world signed the Montreal Protocol on Substances that Deplete the Ozone Layer, which regulated ozone-depleting compounds. Later amendments to the Montreal Protocol completely phased out production of CFCs.

    Past studies have used statistical analyses of changes in the ozone hole’s size to argue that ozone depletion is decreasing. This study is the first to use measurements of the chemical composition inside the ozone hole to confirm that not only is ozone depletion decreasing, but that the decrease is caused by the decline in CFCs.

    The study was published Jan. 4 in the journal Geophysical Research Letters.

    The Antarctic ozone hole forms during September in the Southern Hemisphere’s winter as the returning sun’s rays catalyze ozone destruction cycles involving chlorine and bromine that come primarily from CFCs. To determine how ozone and other chemicals have changed year to year, scientists used data from the Microwave Limb Sounder (MLS) aboard the Aura satellite, which has been making measurements continuously around the globe since mid-2004.

    NASA JPL Caltech Microwave Limb Sounder

    NASA Goddard Aura satellite

    While many satellite instruments require sunlight to measure atmospheric trace gases, MLS measures microwave emissions and, as a result, can measure trace gases over Antarctica during the key time of year: the dark southern winter, when the stratospheric weather is quiet and temperatures are low and stable.

    The change in ozone levels above Antarctica from the beginning to the end of southern winter — early July to mid-September — was computed daily from MLS measurements every year from 2005 to 2016. “During this period, Antarctic temperatures are always very low, so the rate of ozone destruction depends mostly on how much chlorine there is,” Strahan said. “This is when we want to measure ozone loss.”

    They found that ozone loss is decreasing, but they needed to know whether a decrease in CFCs was responsible. When ozone destruction is ongoing, chlorine is found in many molecular forms, most of which are not measured. But after chlorine has destroyed nearly all the available ozone, it reacts instead with methane to form hydrochloric acid, a gas measured by MLS. “By around mid-October, all the chlorine compounds are conveniently converted into one gas, so by measuring hydrochloric acid we have a good measurement of the total chlorine,” Strahan said.

    Nitrous oxide is a long-lived gas that behaves just like CFCs in much of the stratosphere. The CFCs are declining at the surface but nitrous oxide is not. If CFCs in the stratosphere are decreasing, then over time, less chlorine should be measured for a given value of nitrous oxide. By comparing MLS measurements of hydrochloric acid and nitrous oxide each year, they determined that the total chlorine levels were declining on average by about 0.8 percent annually.

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    A view of Earth’s atmosphere from space. Credits: NASA

    The 20 percent decrease in ozone depletion during the winter months from 2005 to 2016 as determined from MLS ozone measurements was expected. “This is very close to what our model predicts we should see for this amount of chlorine decline,” Strahan said. “This gives us confidence that the decrease in ozone depletion through mid-September shown by MLS data is due to declining levels of chlorine coming from CFCs. But we’re not yet seeing a clear decrease in the size of the ozone hole because that’s controlled mainly by temperature after mid-September, which varies a lot from year to year.”

    Looking forward, the Antarctic ozone hole should continue to recover gradually as CFCs leave the atmosphere, but complete recovery will take decades. “CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time,” said Anne Douglass, a fellow atmospheric scientist at Goddard and the study’s co-author. “As far as the ozone hole being gone, we’re looking at 2060 or 2080. And even then there might still be a small hole.”

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    NASA Earth Science

    Earth is a complex, dynamic system we do not yet fully understand. The Earth system, like the human body, comprises diverse components that interact in complex ways. We need to understand the Earth’s atmosphere, lithosphere, hydrosphere, cryosphere, and biosphere as a single connected system. Our planet is changing on all spatial and temporal scales. The purpose of NASA’s Earth science program is to develop a scientific understanding of Earth’s system and its response to natural or human-induced changes, and to improve prediction of climate, weather, and natural hazards.

    A major component of NASA’s Earth Science Division is a coordinated series of satellite and airborne missions for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans. This coordinated approach enables an improved understanding of the Earth as an integrated system. NASA is completing the development and launch of a set of Foundational missions, new Decadal Survey missions, and Climate Continuity missions.

    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 9:44 am on August 13, 2015 Permalink | Reply
    Tags: , NASA Earth Science   

    From NASA Earth: “Putting NASA Earth Data to Work” 

    NASA Earth Observatory

    NASA Earth

    Aug. 13, 2015
    Editor: Stephen Cole

    1

    Satellites orbiting Earth hundreds of miles above the planet’s surface are helping put information into the hands of people around the world who make critical decisions about protecting wildlife, responding to drought and identifying hazards to public health.

    All of this and more is possible due to the application of satellite data and images to improve the ways in which organizations and governments address challenges that society faces. Putting satellite data to work in this way is the goal of the Applied Sciences Program in the Earth Science Division of NASA’s Science Mission Directorate. Many of the ways that NASA Earth science serves society are described in the program’s just-released 2014 Annual Report.

    The report describes how the National Marine Fisheries Service uses environmental data from several satellites to study whale habitats. The service developed with Applied Sciences a means to predict the presence of whales in near-real time. Knowing where whales will be along their migratory routes is critical information for container ships and fishing vessels, which can take measures to avoid interaction with the whales.

    In Bangladesh, flood forecasters used Jason-2 satellite-derived river height data to extend their three-five day forecasts to eight days, giving the public more time to get out of harm’s way. And officials in Ohio used satellite chlorophyll observations to help assess public health risks from, and target responses to, freshwater algal blooms.

    Landsat imagery assisted the California Department of Water Resources to map drought effects on agricultural production in the Central Valley. The state used information on the extent of fallowed land to support decisions on allocation of drought emergency funds to counties for social services for farmworkers and their families.

    The new annual report describes many other ways that Earth science serves society. The online report also includes videos as well as information on applications and satellite mission planning, program performance, support of natural disaster responses, and much more.

    NASA uses the vantage point of space to increase our understanding of our home planet, improve lives, and safeguard our future. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.

    NASA’s work in Earth science is making a difference in people’s lives around the world every day. From farms to our national parks, from today’s response to natural disasters to tomorrow’s air quality, NASA is working for you 24/7. To find out more, click here.

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    The Earth Observatory’s mission is to share with the public the images, stories, and discoveries about climate and the environment that emerge from NASA research, including its satellite missions, in-the-field research, and climate models. The Earth Observatory staff is supported by the Climate and Radiation Laboratory, and the Hydrospheric and Biospheric Sciences Laboratory located at NASA Goddard Space Flight Center.

     
  • richardmitnick 5:45 am on March 14, 2015 Permalink | Reply
    Tags: , , NASA Earth Science,   

    From NASA Earth: “In a Warming World, Storms May Be Fewer but Stronger” 

    NASA Earth Observatory

    NASA Earth Observatory

    March 5, 2013
    By Adam Voiland
    Design by Robert Simmon

    Scientists Investigate How Climate Change Affects Extreme Weather

    Few images are as beautiful and as terrifying as a satellite view of a hurricane about to make landfall. On October 29, 2012, the Suomi NPP satellite captured an ominous nighttime view of Sandy—an enormous hybrid storm that was part hurricane, part Nor‘easter—churning off the coast of New Jersey.

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    Hurricane Sandy approaches the Atlantic coast of the U.S. in the early morning hours of October 29, 2012. (NASA Earth Observatory image by Jesse Allen and Robert Simmon, using VIIRS Day-Night Band data from the Suomi National Polar-orbiting Partnership.)

    NASA Suomi NPP satellite
    NASA Suomi NPP satellite

    The string of city lights that stretches from Washington to Boston was mostly gone, blanketed by thick, ghostly storm clouds. One of the most brightly lit cities in the world, New York, was little more than a faint smudge through Sandy’s clouds.

    In a matter of hours, that smudge of light would go dark. Large swaths of Manhattan were under water. The Rockaways were on fire. Rooftops along the New Jersey shore became temporary islands for people escaping a wall of seawater that surged inland.

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    Hurricane Sandy knocked out power to much of lower Manhattan, New York. (Photograph ©2012 Several seconds.)

    “If you look at the unique set of circumstances in which Sandy emerged and you know something about meteorology and climate,” says Marshall Shepherd, director of the atmospheric sciences program at the University of Georgia, “it’s hard not to ask yourself these kinds of questions.”

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    Research meteorologist Marshall Shepherd compares climate change and weather extremes to steroids and baseball. “Some influence was surely there, but we have more work to do before we can say precisely what percentage.” (Photograph courtesy Marshall Shepherd, University of Georgia Atmospheric Sciences Program.)

    Sandy is not the only recent storm to make people ask questions about climate change and weather. In 2010, an epic winter storm dubbed “Snowmageddon” dumped more than half a meter (2 feet) of snow across many parts of the U.S. East Coast. And in April 2011, tornadoes killed more than 364 Americans—the most ever in a month. The rash of twisters etched scars of destruction on the landscape so long and wide that they could be seen from space. The United States set records in 2011 and 2012 for the number of weather disasters that exceeded $1 billion in losses; most were storms.

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    Hackleburg High School in Alabama was destroyed by a tornado in April 2011. (Photograph courtesy Federal Emergency Management Agency.)

    All of these weather events have happened as the concentration of greenhouse gases in the atmosphere has been rising higher than it has been for at least 100,000 years. Scientists are nearly certain that the buildup of carbon dioxide has already sparked changes in Earth’s atmosphere and ecosystems. The lowest layer of the atmosphere (the troposphere) has warmed markedly, especially at high latitudes. So have the world’s oceans. Heat waves and droughts have grown more likely and more extreme. Arctic ice is melting at a record pace, and the snowy landscapes of the far north have started melting earlier each year.

    Given all the change that has already take place, it’s reasonable to wonder if climate change has affected storms as well. “After the tornadoes in 2011, I was flooded with calls from reporters,” says Anthony Del Genio, a climatologist at NASA’s Goddard Institute for Space Studies (GISS). “People wanted quick, definitive answers. The trouble is that’s not where the science is.”

    Historically, research on tornadoes, hurricanes, and other types of storms has focused on short-term forecasting, not on understanding how storms are changing over time. Reliable, long-term records of storms are scarce, and the different reporting and observing methods have left many scientists and meteorologists feeling skeptical. But the study of storminess and climate has begun to mature, says Del Genio, and a consensus is emerging: for several types of storms, global warming may prime the atmosphere to produce fewer but stronger storms.
    Storms are Getting Stronger

    What exactly does it mean for storms to get “stronger”? Does it mean faster winds? A larger wind field? Lower pressure at the center? More rain and snowfall? Higher storm surges?

    “You have to remember that storms aren’t one-dimensional,” says Del Genio. “There are many types of storms, and sorting out how aspects of each type respond to warming is where the science really gets interesting.”

    5
    As Sandy was moving up the U.S. East Coast, unusually warm ocean temperatures allowed the storm to stay strong after it left tropical waters. (Map by Robert Simmon, using data from the NOAA Earth System Research Laboratory.)

    Rising sea levels exacerbated Sandy’s storm surge, for example, a direct link between global warming and storm damage. And abnormally high sea surface temperatures in the Atlantic probably intensified the storm. But pinning all of Sandy’s fury—its hybrid nature, the scale of its winds, its unusual track—on global warming is premature, says Shepherd, the current president of the American Meteorological Society.

    Weather forecasters use terms like snowstorms, derechos, hailstorms, rainstorms, blizzards, low-pressure systems, lightning storms, hurricanes, typhoons, nor‘easters, and twisters. Research meteorologists and climatologists have a simpler way of dividing up the world’s storms: thunderstorms, tropical cyclones, and extra-tropical cyclones. All are atmospheric disturbances that redistribute heat and produce some combination of clouds, precipitation, and wind.

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    Tropical cyclones, extra-tropical cyclones, and thunderstorms are the three fundamental types of storms studied by the climate change community. (Image ©2013 EUMETSAT.)

    EUMETSAT MeTop satellite
    EUMETSAT MeTop satellite

    Thunderstorms are the smallest type, and they are often part of the larger storm systems (tropical and extra-tropical cyclones). All storms require moisture, energy, and certain wind conditions to develop, but the combination of ingredients varies depending on the type of storm and local meteorological conditions.

    For example, thunderstorms form when a trigger—a cold front, converging near-surface winds, or rugged topography—destabilizes a mass of warm, humid air and causes it to rise. The air expands and cools as it ascends, increasing the humidity until the water vapor condenses into liquid droplets or ice crystals in precipitation-making clouds. The process of converting water vapor into liquid water or ice releases latent heat into the atmosphere. (If this doesn’t make sense, remember that the reverse—turning liquid water into water vapor by boiling it—requires heat).

    Storms feed off of latent heat, which is why scientists think global warming is strengthening storms. Extra heat in the atmosphere or ocean nourishes storms; the more heat energy that goes in, the more vigorously a weather system can churn.

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    Thunderstorms derive their energy from the heat released by the condensation of water vapor. This “latent heat” energy drives thunderstorm clouds high into the atmosphere. Thunderstorms dissipate when the cold downdraft created by falling rain drops stifles rising warm air. (Image adapted from NOAA National Weather Service Life Cycle of a Thunderstorm.)

    Already, there is evidence that the winds of some storms may be changing. A study based on more than two decades of satellite altimeter data (measuring sea surface height) showed that hurricanes intensify significantly faster now than they did 25 years ago. Specifically, researchers found that storms attain Category 3 wind speeds nearly nine hours faster than they did in the 1980s. Another satellite-based study found that global wind speeds had increased by an average of 5 percent over the past two decades.

    There is also evidence that extra water vapor in the atmosphere is making storms wetter. During the past 25 years, satellites have measured a 4 percent rise in water vapor in the air column. In ground-based records, about 76 percent of weather stations in the United States have seen increases in extreme precipitation since 1948. One analysis found that extreme downpours are happening 30 percent more often. Another study found that the largest storms now produce 10 percent more precipitation.

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    Increases in global temperature have raised atmospheric humidity. (Graph by Robert Simmon, based on data from the NOAA National Climatic Data Center.)

    William Lau, a scientist at NASA’s Goddard Space Flight Center, concluded in a 2012 paper that rainfall totals from tropical cyclones in the North Atlantic have risen at a rate of 24 percent per decade since 1988. The increase in precipitation doesn’t just apply to rain. NOAA scientists have examined 120 years of data and found that there were twice as many extreme regional snowstorms between 1961 and 2010 as there were from 1900 to 1960.

    But measuring a storm’s maximum size, heaviest rains, or top winds does not capture the full scope of its power. Kerry Emanuel, a hurricane expert at the Massachusetts Institute of Technology, developed a method to measure the total energy expended by tropical cyclones over their lifetimes. In 2005, he showed that Atlantic hurricanes are about 60 percent more powerful than they were in the 1970s. Storms lasted longer and their top wind speeds had increased by 25 percent. (Subsequent research has shown that the intensification may be related to differences between the temperature of the Atlantic and Pacific oceans.)
    Effects of the Temperature See-Saw

    If understanding the impact of global warming on storms were simply a matter of tallying up extra moisture, the answer would be pretty straightforward. However, reality is more complicated. Putting extra water vapor into the atmosphere is just one of the ways global warming is changing the planet. Another important factor is how the heat in the atmosphere is distributed.

    Since the mid Twentieth Century, average global temperatures have warmed about 0.6°C (1.1°F), but the warming has not occurred equally everywhere. Temperatures have increased about twice as fast in the Arctic as in the mid-latitudes. The loss of sea ice is a key reason why. Bright and reflective ice is giving way to darker, open ocean—amplifying the warming trend by absorbing more heat from the Sun. On the other hand, the abundance of convection and thunderstorms in the tropics contributes to a slower rate of warming by transporting heat away from the surface.

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    Global temperatures from 2000–2009 were on average about 0.6°C higher than they were from 1951–1980. The Arctic, however, was about 2°C warmer. (NASA image by Robert Simmon, with GISS Surface Temperature Analysis (GISTEMP). data.)

    Climatologists think the differing rates of warming from the equator to the poles could have a significant impact on some types of storms. Extra-tropical cyclones, for example, harvest energy from the atmosphere when masses of warm and cold air interact along the polar front—the boundary between cooler polar air and warmer subtropical air. As the difference between the temperature at the poles and the tropics decreases, there could be less energy for these storms to absorb, a change that could weaken them or make them less frequent.

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    Temperatures are warming more near the poles than near the equator. This plot shows the change in temperature versus latitude from 1880 to 2012. The reduced temperature contrast between high latitudes and the tropics likely weakens extra tropical cyclones. (NASA image by Robert Simmon, with GISS Surface Temperature Analysis (GISTEMP) data.)

    “Sorting out opposing factors is what makes this such a challenging problem,” Del Genio says. “And keep in mind that this is a simplification. These aren’t the only two factors involved.”

    Wind shear—a measure of how the speed and direction of winds differ at different levels of the atmosphere—complicates the picture because it can affect storms in a variety of ways. Tropical cyclones require weak wind shear; in other words, they need minimal differences in wind speeds at adjacent levels of the atmosphere. Strong wind shear tears tropical cyclones apart, preventing heat and moisture from organizing into a storm core.

    Research suggests that Atlantic wind shear could increase by 1 to 2 miles (1.6 to 3.2 kilometers) per hour for each degree that global temperatures increase. It’s this potential increase that explains why many climate simulators conclude that the number of tropical cyclones will stay the same or decrease even as the strongest storms get stronger. An article published in 2010 by a group of the world’s leading storm experts concluded that the average intensity of tropical cyclones will likely increase by 2 to 11 percent by 2100, but the overall frequency of storms will decrease between 6 and 34 percent.

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    Hurricane Felix hovers over the Caribbean Sea, as viewed from the International Space Station on September 3, 2007. (Astronaut photograph ISS015-E-25054.)

    Another complicating factor is that the same changes in equator-to-pole temperatures that could influence storm formation could also affect the winds that steer them. For instance, jet streams—meandering streams of fast-moving air that play a key role in steering storms—could speed up or slow down. A sluggish jet stream would mean slower-moving storms that could dump heavier loads of rain and snow, especially in coastal areas.

    Preliminary research by Jennifer Francis of Rutgers University suggests that the jet stream’s west-to-east winds have slowed and grown wavier since 1979 because of the loss of Arctic sea ice. Francis has argued that the changes may have contributed to extreme weather events in recent years by creating large dips or kinks in the jet stream—what meteorologists call “blocking” patterns.

    Blocking patterns are areas of persistently high pressure that often accompany extreme weather. It was a blocking high, for example, that led to long-lived downpours and devastating flooding in Pakistan in 2010. And it was a similar persistent blocking pattern that caused record melting in Greenland in the summer of 2012 and helped push Superstorm Sandy inland rather than out to sea.
    Competing Forces Muddle the Picture

    Although more rain and snow are falling from storms, it’s more difficult to say how global warming will affect the formation of those storms in the first place. “This would be a much easier nut to crack if the effects of warming all pointed to more frequent, stronger storms,” says Harold Brooks, a meteorologist at NOAA’s National Severe Storms Laboratory. “Unfortunately, they don’t.”

    Though thunderstorms are familiar and seemingly non-threatening, severe thunderstorms—with sustained winds above 93 kilometers (58 miles) per hour or with unusually large hail—can lead to supercells, derechos, and tornadoes. Several key ingredients are required for severe thunderstorms, starting with the presence of warm, moist air near the surface and a store of potential energy once that air begins to rise. Meteorologists call this combination “convective available potential energy,” or CAPE. The higher the CAPE, the more potential an air mass has to create the towering cumulus clouds that create storms.

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    Lightning only occurs in areas with strong convection. This map of lightning strike frequency from May 1995 through 2011 shows where severe weather occurs around the world. Scientists are using computer models to predict if global warming will cause an increase in the number and strength of thunderstorms. (NASA image by Robert Simmon, using data from the MSFC Global Hydrology Resource Center.)

    “CAPE can provide storms with the raw fuel to produce rain and hail,” says Brooks, “and vertical wind shear can pull and twist weak storms into strong, windy ones.”

    Climate change should, theoretically, increase potential storm energy by warming the surface and putting more moisture in the air through evaporation, Brooks explained. But on the other hand, disproportionate warming in the Arctic should lead to less wind shear in the mid-latitude areas prone to severe thunderstorms, making the storms less likely.

    In recent years, Del Genio conducted simulations to assess global warming’s impact on thunderstorms in the United States. Working with a climate model maintained by the Goddard Institute for Space Studies, he found that the number of severe storms would not change much, but the strongest storms would have even stronger and more destructive winds.

    Another study, led by Robert Trapp of Purdue University, found that a doubling of greenhouse gases in the atmosphere would significantly increase the number of days that severe thunderstorms could occur in the southern and eastern United States. Cities such as Atlanta and New York could see a doubling of the number of days that severe thunderstorms could occur, the models suggested. “The increase in CAPE more than compensated for the decrease in wind shear,” Trapp says.

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    Detailed climate models of the United States are helping scientists determine the effect of future climate change on storms. These maps show the results of one model comparing the summer climate in 2072–2099 with the climate in 1962–1989. Convective available potential energy is predicted to rise enough to overwhelm a slight decrease in vertical wind shear, leading to an increase in severe thunderstorms, especially in Missouri and coastal North and South Carolina. (Images adapted from Trapp et al., 2007.)

    However, both scientists caution that there’s uncertainty in their findings because of the meager scientific attention thunderstorms have received. Unlike tropical cyclones, which climate researchers have studied intensely since Hurricane Katrina struck New Orleans in 2005, only a handful of researchers have focused on the impact of global warming on severe thunderstorms.

    Then there are problems unique to tornadoes. Beyond knowing that they require a certain type of wind shear, meteorologists just don’t know much about why some thunderstorms generate tornadoes and others don’t. (Only about 1 percent of thunderstorms generate tornadoes.) “You can’t just take the results of the modeling for severe thunderstorms and assume they apply to tornadoes,” says Del Genio.

    Similar problems confound research about extra-tropical and tropical cyclones. Conventional wisdom holds that extra-tropical cyclones will be somewhat less likely in a warmer world because the differences in temperatures between the tropics and the Arctic—one of the key elements fueling extra-tropical storms—should decline.

    But again, there are competing forces. At higher altitudes in the upper troposphere—above 5 kilometers (3 miles)—the air is warming more quickly at the equator than at the poles. Since upper troposphere temperatures and winds are key to the formation of extra-tropical cyclones, changes at that level could counteract changes lower in the atmosphere.

    Can Models Provide an Answer?

    Due to gaps and limitations in historical records of storms, some scientists have turned to general circulation models (GCMs) for answers. GCMs are computer models that divide the globe up into three-dimensional grids, with the side of each box typically representing about 150 to 200 kilometers (90 to 125 miles) of the Earth. The conditions within each box are defined by equations that depict features of the oceans and atmosphere, such as temperature, humidity, pressure, and wind. The models also include factors that can affect those features, such as the concentration of greenhouse gases, the reflectivity of Earth’s surface, or the distribution of clouds or aerosols.

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    New, high-resolution computer models are increasingly capable of resolving small features in the atmosphere. The GEOS-5 model, running at a resolution of 3.5 kilometers (2.2 miles) per grid cell, simulated the state of the atmosphere on January 2, 2009. (NASA image by Greg Shirah, GSFC Scientific Visualization Studio.)

    Models are useful because they make it possible to parse out how each different factor might influence climate in a given location. By adding, removing, and adjusting the variables, scientists can develop a deeper understanding of how the many pieces of the climate puzzle fit together.

    “Models allow us to test hypotheses and improve our understanding in ways that no other type of experiment can,” says Del Genio. “They are criticized for predicting things ‘wrong’ and for the lack of agreement between them. But a model simulation that predicts something incorrectly can be just as useful for revealing underlying processes as a model run that gets the ‘right’ answer.”

    Climate models are quite good at working out features of the atmosphere on a broad scale, and they do a reasonably good job of simulating large extra-tropical cyclones, which can stretch hundreds of kilometers. But they struggle to simulate hurricanes or thunderstorms, and they cannot produce key details (such as the heaviest bands of wind and rain) in extra-tropical storms. Hurricanes are generally about 150 kilometers (90 miles) across; an individual thunderstorm is usually less than 10 kilometers (6 miles). Both are smaller than the typical grid boxes in a climate model.

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    Thunderstorms are smaller than the resolution of a typical global climate model. However, a new generation of regional models that include high-resolution, real-world data now provide scientists with a detailed look at thunderstorms and other small-scale features of the atmosphere. (Astronaut photograph ISS022-E-006510.)

    To address this problem, climate modelers have started to develop a new generation of models that reduce the size of the boxes in key regions by “downscaling.” One way they do this is by adding very detailed information about something that’s well known, like topography, into a low-resolution climate model. They also add ever-more detailed information from real-world satellites.

    “Downscaling to simulate storms is a bit like knowing that you have a low-resolution image of a face that’s so blurry you can hardly tell what it is,” explained Gavin Schmidt, a climate modeler at NASA’s Goddard Institute for Space Studies. “You take clues from a low-resolution image and then map them with other information about things like eye color, skin colors, and nose shapes to construct a more reasonable image of what the face really looks like.”

    Trapp’s research group at Purdue, for example, used downscaling to incorporate data from a coarse climate model into a finer-resolution weather forecasting model. This made it possible to resolve some individual thunderstorms in the central United States and even some of the smaller elements of storms. Overall, the model captured daily rainfall patterns with surprising accuracy over a ten-year period.

    “No model can predict the future perfectly,” says Del Genio. “But there’s no question that models are helping us with the underlying science.”

    In some cases, the work has just begun. While climatologists have extensively studied tropical storms, they’ve hardly studied some of the more exotic types of storms. Sandy, for example, began in the Caribbean as a typical tropical storm but then morphed into a “hybrid” with extra-tropical characteristics. While tropical cyclones draw their energy from warm ocean waters, extra-tropical cyclones are fueled by sharp temperature differences between fronts in the atmosphere. Sandy was able to tap energy from both sources, which is part of the reason it was so destructive.

    16
    “No model can predict the future perfectly,” says Del Genio. “But there’s no question that models are helping us with the underlying science.” NASA Goddard Institute for Space Studies.)

    Shepherd does think warming had an influence on Sandy, but he advises against rushing to judgment. “We do not know whether superstorms like Sandy are harbingers of a ‘new normal’, he says. “It’s a bit like steroids usage and home run statistics for baseball. Some influence was surely there, but we have more work to do before we can say precisely what percentage of home runs were helped by steroids.”

    And then, of course, the inherent variability of the oceans and atmosphere means storm trends don’t follow straightforward patterns. After the record-shattering tornado outbreaks of 2011, for instance, the year 2012 was unusually quiet.

    “There was a strong impulse to over-interpret and attribute tornadoes to climate change in 2011,” says Del Genio. “2012 was a good reminder that we can’t do that. We have to be patient if we really want to understand the relationship between storms and climate. The attribution is about trends and understanding underlying processes. It is not about flagging individual events with some sort of scarlet letter.”

    References
    Brooks, H. (2013, April 1) Severe thunderstorms and climate change. Atmospheric Research, 123, 129-138.
    Climate Central (2013, January 11) U.S. Sets Record for Days Without a Deadly Tornado. Accessed March 1, 2013.
    Cooney, C. (2012, January 1) Downscaling Climate Models: Sharpening the Focus on Local-Level Changes. Environmental Health Perspectives, 120 (1), 22-29.
    Del Genio, A. et al (2007, August 17) Will moist convection be stronger in a warmer climate? Geophysical Research Letters, 34 (16), 16703.
    Del Genio, A. (2011, April 16) Will a Warmer World Be Stormier? Earthzine. Accessed March 1, 2013.
    Diffenbaugh, N. et al (2012, December 19) Does Global Warming Influence Tornado Activity? Eos, 89 (53), 553-554.
    Emanuel, K. (2005, August 4) Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 436, 686-688.
    Francis, J. and Vavrus, J. (2012, March 17) Evidence linking Arctic amplification to extreme weather in mid-latitudes. Geophysical Research Letters, 39 (6), 801.
    Kishtawal, C. et al (2012, May 26) Tropical cyclone intensification trends during satellite era (1986-2010). Geophysical Research Letters, 39 (10), 810.
    Knutson, T. et al (2010, February 21) Tropical cyclones and climate change. Nature Geoscience, 3, 157-163.
    Knutson, T. et al (2008, May 18) Simulated reduction in Atlantic hurricane frequency under twenty-first-century conditions. Nature Geoscience, 1, 359-364.
    Kunkel, K. et al (2012) Monitoring and Understanding Trends in Extreme Storms: State of the Knowledge. Bulletin of the American Meteorological Society.
    Kunkel, K. et al (2010, December 23) Recent increase in U.S. heavy precipitation associated with tropical cyclones. Geophysical Research Letters, 37 (24), 706.
    Lau, W. and Zhou, Y. (2012, February 1) Observed recent trends in tropical cyclone rainfall over the North Atlantic and North Pacific. Journal of Geophysical Research Atmospheres. 117 (D3), 104.
    Masters, J. (2008, May 21) The future of wind shear. Weather Underground. Accessed March 1, 2013.
    Pryor, S. et al (2008, March 28). How spatially coherent and statistically robust are temporal changes in extreme precipitation in the contiguous USA? International Journal of Climatology, 29 (1), 31-45.
    Shepherd, M. and Knox, J. (2012, October 31) Hurricane Sandy and Climate Change. Project Syndicate. Accessed March 1, 2013.
    Slate (2012, October 29) Hybrid Hell. Accessed March 1, 2013.
    Trapp, R. et al (2007, December 4) Changes in severe thunderstorm environment frequency during the 21st century caused by anthropogenically enhanced global radiative forcing. Proceedings of the National Academy of Sciences, 104 (50), 19719-19723.
    Trapp, R. et al (2010, May 10) Regional climate of hazardous convective weather through high-resolution downscaling. Climate Dynamics, 37 (3-4), 677-688.
    Vecchi, G. and Soden, B. (2007, April 18) Increased tropical Atlantic wind shear in model projections of global warming. Geophysical Research Letters, 34 (8), 702.

    Further Reading
    Bengtsson, L. et al (2009, May) Will Extratropical Storms Intensify in a Warmer Climate? Journal of Climate, 22(9), 2276-2301.
    Champion, A. et al (2011, August 17) Impact of increasing resolution and a warmer climate on extreme weather from Northern Hemisphere extratropical cyclones. Tellus, 63 (5).
    Live Science (2012, September 7) Hurricanes Whip up Faster in a Warming World. Accessed March 1, 2013.
    Masters, J. (2010, March 3) The future of intense winter storms. Weather Underground. Accessed March 1, 2013.
    NOAA Severe Weather 101:Tornado Basics. Accessed March 1, 2013.
    NOAA Large-scale Climate Projections and Hurricanes. Accessed March 1, 2013.
    Ulbrich, U. et al (2009, January 17) Extra-tropical cyclones in the present and future climate: A review. Theoretical Applied Climatology, 98 (1-2), 117-131.
    University of Rhode Island Hurricane Science. Accessed March 1, 2013.

    See the full article here.

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    The Earth Observatory’s mission is to share with the public the images, stories, and discoveries about climate and the environment that emerge from NASA research, including its satellite missions, in-the-field research, and climate models. The Earth Observatory staff is supported by the Climate and Radiation Laboratory, and the Hydrospheric and Biospheric Sciences Laboratory located at NASA Goddard Space Flight Center.

     
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    From NASA: “NASA Study Finds Carbon Emissions Could Dramatically Increase Risk of U.S. Megadroughts” 

    NASA

    NASA


    NASA scientists used tree rings to understand past droughts and climate models incorporating soil moisture data to estimate future drought risk in the 21st century. Image Credit: NASA’s Goddard Space Flight Center

    Droughts in the U.S. Southwest and Central Plains during the last half of this century could be drier and longer than drought conditions seen in those regions in the last 1,000 years, according to a new NASA study.

    The study, published Thursday in the journal Science Advances, is based on projections from several climate models, including one sponsored by NASA. The research found continued increases in human-produced greenhouse gas emissions drives up the risk of severe droughts in these regions.

    “Natural droughts like the 1930s Dust Bowl and the current drought in the Southwest have historically lasted maybe a decade or a little less,” said Ben Cook, climate scientist at NASA’s Goddard Institute for Space Studies and the Lamont-Doherty Earth Observatory at Columbia University in New York City, and lead author of the study. “What these results are saying is we’re going to get a drought similar to those events, but it is probably going to last at least 30 to 35 years.”

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    Soil moisture 30 cm below ground projected through 2100 for high emissions scenario RCP 8.5. The soil moisture data are standardized to the Palmer Drought Severity Index and are deviations from the 20th century average. Image Credit: NASA’s Goddard Space Flight Center

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    Soil moisture 30 cm below ground projected through 2100 for moderate emissions scenario RCP 4.5. The soil moisture data are standardized to the Palmer Drought Severity Index and are deviations from the 20th century average. Image Credit: NASA’s Goddard Space Flight Center

    According to Cook, the current likelihood of a megadrought, a drought lasting more than three decades, is 12 percent. If greenhouse gas emissions stop increasing in the mid-21st century, Cook and his colleagues project the likelihood of megadrought to reach more than 60 percent.

    However, if greenhouse gas emissions continue to increase along current trajectories throughout the 21st century, there is an 80 percent likelihood of a decades-long megadrought in the Southwest and Central Plains between the years 2050 and 2099.

    The scientists analyzed a drought severity index and two soil moisture data sets from 17 climate models that were run for both emissions scenarios. The high emissions scenario projects the equivalent of an atmospheric carbon dioxide concentration of 1,370 parts per million (ppm) by 2100, while the moderate emissions scenario projects the equivalent of 650 ppm by 2100. Currently, the atmosphere contains 400 ppm of CO2.

    In the Southwest, climate change would likely cause reduced rainfall and increased temperatures that will evaporate more water from the soil. In the Central Plains, drying would largely be caused by the same temperature-driven increase in evaporation.

    The Fifth Assessment Report, issued by the United Nations Intergovernmental Panel on Climate Change (IPCC) in 2013, synthesized the available scientific studies and reported that increases in evaporation over arid lands are likely throughout the 21st century. But the IPCC report had low confidence in projected changes to soil moisture, one of the main indicators of drought.

    Until this study, much of the previous research included analysis of only one drought indicator and results from fewer climate models, Cook said, making this a more robust drought projection than any previously published.

    “What I think really stands out in the paper is the consistency between different metrics of soil moisture and the findings across all the different climate models,” said Kevin Anchukaitis, a climate scientist at the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts, who was not involved in the study. “It is rare to see all signs pointing so unwaveringly toward the same result, in this case a highly elevated risk of future megadroughts in the United States.”

    This study also is the first to compare future drought projections directly to drought records from the last 1,000 years.

    “We can’t really understand the full variability and the full dynamics of drought over western North America by focusing only on the last century or so,” Cook said. “We have to go to the paleoclimate record, looking at these much longer timescales, when much more extreme and extensive drought events happened, to really come up with an appreciation for the full potential drought dynamics in the system.”

    Modern measurements of drought indicators go back about 150 years. Cook and his colleagues used a well-established tree-ring database to study older droughts. Centuries-old trees allow a look back into the distant past. Tree species like oak and bristle cone pines grow more in wet years, leaving wider rings, and vice versa for drought years. By comparing the modern drought measurements to tree rings in the 20th century for a baseline, the tree rings can be used to establish moisture conditions over the past 1,000 years.

    The scientists were interested in megadroughts that took place between 1100 and 1300 in North America. These medieval-period droughts, on a year-to-year basis, were no worse than droughts seen in the recent past. But they lasted, in some cases, 30 to 50 years.

    When these past megadroughts are compared side-by-side with computer model projections of the 21st century, both the moderate and business-as-usual emissions scenarios are drier, and the risk of droughts lasting 30 years or longer increases significantly.

    Connecting the past, present and future in this way shows that 21st century droughts in the region are likely to be even worse than those seen in medieval times, according to Anchukaitis.

    “Those droughts had profound ramifications for societies living in North America at the time. These findings require us to think about how we would adapt if even more severe droughts lasting over a decade were to occur in our future,” Anchukaitis said.

    NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

    For more information about NASA’s Earth science activities, visit:

    http://www.nasa.gov/earthrightnow

    See the full article here.

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    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 2:41 pm on February 11, 2015 Permalink | Reply
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    From NASA Earth Sciences: “NASA Study Shows Global Sea Ice Diminishing, Despite Antarctic Gains” 

    NASA

    NASA

    February 10, 2015
    Maria-José Viñas
    NASA’s Earth Science News Team

    Sea ice increases in Antarctica do not make up for the accelerated Arctic sea ice loss of the last decades, a new NASA study finds. As a whole, the planet has been shedding sea ice at an average annual rate of 13,500 square miles (35,000 square kilometers) since 1979, the equivalent of losing an area of sea ice larger than the state of Maryland every year.

    “Even though Antarctic sea ice reached a new record maximum this past September, global sea ice is still decreasing,” said Claire Parkinson, author of the study and climate scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “That’s because the decreases in Arctic sea ice far exceed the increases in Antarctic sea ice.”

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    Before
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    Arctic sea ice coverage has been on the decline since scientists started monitoring its extent with satellites in 1979. The lowest extent on record was reached on Sept. 16, 2012, and it was approximately half the size of the average extent from 1979 to 2000. These maps show the minimum extent of Arctic sea ice in October of 1979 and 2013 as observed by satellite. October is typically the global maximum for sea ice, though it is just past the minimum in the Arctic.
    Image Credit:
    NASA’s Earth Observatory/Joshua Stevens and Jesse Allen

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    Sea ice surrounding Antarctica has been expanding since the beginning of the satellite record in 1979, reaching a new record extent of over 7.72 million square miles on Sept. 19, 2014. Still, this upward trend pales in comparison to the rapid loss of sea ice in the Arctic. These maps show the maximum extent of Antarctic sea ice in 1979 and 2013 as observed by satellite. October is typically the global maximum for sea ice, largely because of the vast extent of Antarctic ice at that time.
    Image Credit:
    NASA’s Earth Observatory/Joshua Stevens and Jesse Allen

    Parkinson used microwave data collected by NASA and Department of Defense satellites for her study, which was published last December in the Journal of Climate. She added Arctic and Antarctic sea ice extents month by month from November 1978 to December 2013 to determine the global ice extent for each month. Her analysis shows that over the 35-year period, the trend in ice extents was downward in all months of the year, even those corresponding to the Arctic and Antarctic sea ice maximum extents.

    5
    Comparing Arctic sea ice loss to Antarctic sea ice gain shows that the planet has-been shedding sea ice at an average annual rate of 13,500 square miles since 1979, the equivalent of losing an area of sea ice larger than the state of Maryland every year.
    Image Credit:
    NASA’s Earth Observatory/Joshua Stevens and Jesse Allen

    Furthermore, the global ice decrease has accelerated: in the first half of the record (1979-96), the sea ice loss was about 8,300 square miles (21,500 square kilometers) per year. This rate more than doubled for the second half of the period (1996 to 2013), when there was an average loss of 19,500 square miles (50,500 square kilometers) per year – an average yearly loss larger than the states of Vermont and New Hampshire combined.

    “This doesn’t mean the sea ice loss will continue to accelerate,” Parkinson said. “After all, there are limits. For instance, once all the Arctic ice is gone in the summer, the Arctic summertime ice loss can’t accelerate any further.”

    Sea ice has diminished in almost all regions of the Arctic, whereas the sea ice increases in the Antarctic are less widespread geographically. Although the sea ice cover expanded in most of the Southern Ocean between 1979 and 2013, it decreased substantially in the Bellingshausen and Amundsen seas. These two seas are close to the Antarctic Peninsula, a region that has warmed significantly over the last decades.

    In her study, Parkinson also shows that the annual cycle of global ice extents is more similar to the annual cycle of the Antarctic ice than the Arctic ice. The global minimum ice extent occurs in February of each year, as does the Antarctic minimum extent, and the global maximum sea ice extent occurs in either October or November, one or two months after the Antarctic maximum. This contrasts with the Arctic minimum occurring in September and the Arctic maximum occurring in March. Averaged over the 35 years of the satellite record, the planet’s monthly ice extents range from a minimum of 7.03 million square miles (18.2 million square kilometers) in February to a maximum of 10.27 million square miles (26.6 million square kilometers) in November.

    “One of the reasons people care about sea ice decreases is that sea ice is highly reflective whereas the liquid ocean is very absorptive,” Parkinson said. “So when the area of sea ice coverage is reduced, there is a smaller sea ice area reflecting the sun’s radiation back to space. This means more retention of the sun’s radiation within the Earth system and further heating.”

    Parkinson doesn’t find it likely that the Antarctic sea ice expansion will accelerate and overturn the global sea ice negative trend in the future.

    “I think that the expectation is that, if anything, in the long-term the Antarctic sea ice growth is more likely to slow down or even reverse,” she said.

    Parkinson calculated and published the global results after witnessing the public’s confusion about whether Antarctic sea ice gain might be cancelling out Arctic sea ice loss.

    “When I give public lectures or talk with random people interested in the topic, often somebody will say something in the order of ‘well, the ice is decreasing in the Arctic but it’s increasing in the Antarctic, so don’t they cancel out?’” Parkinson said. “The answer is no, they don’t cancel out.”

    6
    Before
    7
    After
    These maps show the maximum extent of Arctic sea ice in February 1979 and 2013 as observed by satellite. February is the month of the global minimum, though it is just before the annual maximum in the Arctic.
    Image Credit:
    NASA’s Earth Observatory/Joshua Stevens and Jesse Allen

    8
    Before
    9
    After
    These maps show the minimum extent of Arctic sea ice in February 1979 and 2013 as observed by satellite.
    Image Credit:
    NASA’s Earth Observatory/Joshua Stevens and Jesse Allen

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 2:43 pm on January 28, 2015 Permalink | Reply
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    From NASA Earth Science: “Global is the new local: Pollution changes clouds, climate downstream” 

    NASA

    NASA

    January 26, 2015
    Carol Rasmussen, NASA’s Earth Science News Team


    This video shows aerosol emission and transport from September 1, 2006 to April 10, 2007. Also included are locations, indicated by red and yellow dots, of wildfires and human-initiated burning as detected by the MODIS instrument on NASA’s Terra and Aqua satellites. Credit: NASA Goddard Space Flight Center.

    NASA AQUA MODIS
    MODIS

    NASA Terra satellite
    Terra

    NASA Aqua satellite
    AQUA

    The residents of Beijing and Delhi are not the only ones feeling the effects of Asian air pollution — an unwanted byproduct of coal-fired economic development. The continent’s tainted air is known to cross the Pacific Ocean, adding to homegrown air-quality problems on the U.S. West Coast.

    But unfortunately, pollution doesn’t just pollute. Researchers at NASA’s Jet Propulsion Laboratory and the California Institute of Technology, both in Pasadena, California, are looking at how Asian pollution is changing weather and climate around the globe.

    Scientists call airborne particles of any sort — human-produced or natural — aerosols. The simplest effect of increasing aerosols is to increase clouds. To form clouds, airborne water vapor needs particles on which to condense. With more aerosols, there can be more or thicker clouds. In a warming world, that’s good. Sunlight bounces off cloud tops into space without ever reaching Earth’s surface, so we stay cooler under cloud cover.

    But that simplest effect doesn’t always happen. If there’s no water vapor in the air — the air is dry — aerosols can’t make clouds. Different types of aerosols have different effects, and the same aerosol can have different effects depending on how much is in the air and how high it is. Soot particles at certain altitudes can cause cloud droplets to evaporate, leaving nothing but haze. At other altitudes, soot can cause clouds to be deeper and taller, producing heavy thunderstorms or hailstorms. With so many possibilities, aerosols are one of the largest sources of uncertainty in predicting the extent of future climate change.

    The experiments and result

    During the last 30 years, clouds over the Pacific Ocean have grown deeper, and storms in the Northwest Pacific have become about 10 percent stronger. This is the same time frame as the economic boom in Asia. JPL researcher Jonathan Jiang and his postdoctoral fellow, Yuan Wang, designed a series of experiments to see if there was a connection between the two phenomena.

    They used a numerical model that included weather factors such as temperature, precipitation and barometric pressure over the Pacific Ocean as well as aerosol transport — the movement of aerosols around the Earth. They did two sets of simulations. The first used aerosol concentrations thought to have existed before the Industrial Revolution. The other used current aerosol emissions. The difference between the two sets showed the effects of increased pollution on weather and climate.

    2
    An extra-tropical cyclone seen in the Pacific Ocean off the coast of Japan on March 10, 2014, by NASA’s GPM Microwave Imager.

    NASA GPM Microwave Imager
    NASA’s GPM Microwave Imager

    “We found that pollution from China affects cloud development in the North Pacific and strengthens extratropical cyclones,” said Wang. These large storms punctuate U.S. winters and springs about once a week, often producing heavy snow and intense cold.

    Wang explained that increased pollution makes more water condense onto aerosols in these storms. During condensation, energy is released in the form of heat. That heat adds to the roiling upward and downward airflows within a cloud so that it grows deeper and bigger.

    “Large, convective weather systems play a very important role in Earth’s atmospheric circulation,” Jiang said, bringing tropical moisture up to the temperate latitudes. The storms form about once a week between 25 and 50 degrees north latitude and cross the Pacific from the southwest to the northeast, picking up Asia’s pollutant outflow along the way.

    Wang thinks the cold winter that the U.S. East endured in 2013 probably had something to do with these stronger extratropical cyclones. The intense storms could have affected the upper-atmosphere wind pattern, called the polar jet stream.

    Jiang and Wang are now working on a new experiment to analyze how increased Asian emissions are affecting weather even farther afield than North America. Although their analysis is in a preliminary stage, it suggests that the aerosols are having a measurable effect on climatic conditions around the globe.

    Conceptualizing Earth differently

    How much these climate effects will increase in the coming decades is an open question. How much they can be reversed if emissions are reduced in Asia also remains unclear.

    The researchers pointed out that their work should raise even more red flags about aerosol-based geoengineering solutions — interventions in the Earth system intended to counteract global warming. Some groups have suggested that we could inject sulfate aerosols into the stratosphere to block incoming sunlight, but Jiang and Wang found that sulfates are the most effective type of aerosol for deepening extratropical cyclones. Ongoing injections would bring more stormy winter weather globally and would likely change the climate in other ways we cannot yet foresee.

    Jiang noted that Asian emissions have made him and some other climate researchers conceptualize Earth differently. “Before, we thought about the North-South contrast: the Northern Hemisphere has more land, the Southern Hemisphere has more ocean. That difference is important to global atmospheric circulation. Now, in addition to that, there’s a West-East contrast. Europe and North America are reducing emissions; Asia is increasing them. That change also affects the global circulation and perturbs the climate.”

    See the full article here.

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
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