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  • richardmitnick 2:51 pm on November 14, 2014 Permalink | Reply
    Tags: , , , , , , Weather   

    From McGill: “Mars, too, has macroweather” 

    McGill University

    McGill University

    13 Nov 2014
    Contact: Chris Chipello
    Organization: Media Relations Office
    Email: christopher.chipello@mcgill.ca
    Office Phone: 514-398-4201

    But weather forecasting on the Red Planet is likely to be even trickier than on Earth.

    Weather, which changes day-to-day due to constant fluctuations in the atmosphere, and climate, which varies over decades, are familiar. More recently, a third regime, called “macroweather,” has been used to describe the relatively stable regime between weather and climate.

    A new study by researchers at McGill University and UCL [University College <London] finds that this same three-part pattern applies to atmospheric conditions on Mars. The results, published in Geophysical Research Letters, also show that the sun plays a major role in determining macroweather.

    Mars
    Mars global mosaic from Viking

    The research promises to advance scientists’ understanding of the dynamics of Earth’s own atmosphere – and could provide insights into the weather of Venus, Saturn’s moon Titan, and possibly the gas giants Jupiter, Saturn, Uranus and Neptune.

    The scientists chose to study Mars for its wealth of data with which to test their theory that a transitional “macroweather” regime exists on other planets. They used information collected from Viking – a Mars lander mission during the 1970s and 1980s — and more recent data from a satellite orbiting Mars.

    NASA Viking 1
    NASA/Mars Viking

    By taking into account how the sun heats Mars, as well as the thickness of the planet’s atmosphere, the scientists predicted that Martian temperature and wind would fluctuate similarly to Earth’s – but that the transition from weather to macroweather would take place over 1.8 Martian days (about two Earth days), compared with a week to 10 days on Earth.

    “Our analysis of the data from Mars confirmed this prediction quite accurately,” said Shaun Lovejoy, a physics professor at McGill University in Montreal and lead author of the paper. “This adds to evidence, from studies of Earth’s atmosphere and oceans, that the sun plays a central role in shaping the transition from short-term weather fluctuations to macroweather.”

    The findings also indicate that weather on Mars can be predicted with some skill up to only two days in advance, compared to Earth’s 10 days.

    Co-author Professor Jan-Peter Muller from the UCL Mullard Space Science Laboratory, said: “We’re going to have a very hard time predicting the weather on Mars beyond two days given what we have found in weather records there, which could prove tricky for the European lander and rover!”

    See the full article here.

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    All about McGill

    With some 300 buildings, more than 38,500 students and 250,000 living alumni, and a reputation for excellence that reaches around the globe, McGill has carved out a spot among the world’s greatest universities.

    Founded in Montreal, Quebec, in 1821, McGill is a leading Canadian post-secondary institution. It has two campuses, 11 faculties, 11 professional schools, 300 programs of study and some 39,000 students, including more than 9,300 graduate students. McGill attracts students from over 150 countries around the world, its 8,200 international students making up 21 per cent of the student body.

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  • richardmitnick 10:03 am on November 14, 2014 Permalink | Reply
    Tags: , , Weather   

    From livescience- “Snowvember: What’s Causing the Unseasonably Cold Weather?” 

    Livescience

    November 13, 2014
    Elizabeth Palermo

    More than a month before the official start of winter, residents of parts of the United States are being blanketed with snow and hit with frigid temperatures. But the infamous polar vortex that sent Americans shivering last January isn’t the only weather system responsible for this unseasonably cold weather, experts say.

    pv
    The typical polar vortex configuration in November, 2013.

    pv2
    A wavy polar vortex on January 5, 2014.

    The early onset of winter has manifested itself in different ways across the country, dumping more than 2 feet (0.6 meters) of snow in parts of Michigan and sending temperatures plummeting in places like Colorado. Even states in the South haven’t been spared. In San Antonio, Texas, residents are enduring temperatures that are a full 20 degrees colder than average for this time of year.

    typ
    On Nov. 5, NASA’s aqua satellite captured this image of Typhoon Nuri, the storm that combined with an extra-tropical system to form the low pressure system known as the “Bering Sea bomb.” That weather system is, in part, responsible for the cold weather now chilling the U.S.
    Credit: NASA Goddard MODIS Rapid Response Team

    NASA Aqua satellite
    NASA/Aqua

    It’s easy to pin the blame for this wintry blast on the so-called polar vortex, a swirling mass of frigid air typically found over the Arctic that occasionally ventures southward. But the vortex is just one of the culprits for this week’s cold snap, said Tom Kines, a senior meteorologist with AccuWeather.

    “It helped deliver the cold air, but the so-called polar vortex isn’t going to be sitting over the U.S. for days and days,” Kines told Live Science. In fact, the vortex is retreating northward into Canada right now, he said.

    The reason the cold weather isn’t heading back north with the polar vortex is simple: There’s something in its way. That something is a jet stream, a river of wind that typically sits about 20,000 feet (6,100 m) or more above the Earth’s surface and influences how air masses and weather systems are distributed.

    “Not only does the jet stream guide weather systems across the country, it also separates warm air masses in the South from those cold air masses in the North,” Kines said. “When the jet stream is north of a particular location, that region usually experiences mild weather because [the jet stream] is kind of blocking the cold air.”

    But as the people shoveling snow in Michigan already know, the jet stream has not been blocking any cold for several days now. The jet stream has plunged southward, Kines said, and the cold air generated by the polar vortex has plunged with it.

    “It’s kind of like opening the floodgates: When the jet stream plunged south, so did that cold air,” Kines said.

    This particular polar vortex was strengthened by recent weather events in Alaska — in particular, the so-called “Bering Sea bomb,” a record-breaking low pressure system that formed over the Pacific Ocean when Typhoon Nuri merged with an extra-tropical system from Siberia, said Roberto Mera, a postdoctoral researcher in the Department of Marine, Earth and Atmospheric Sciences at North Carolina State University.

    The Bering Sea bomb caused a strong bend in the jet stream pattern, forming a sort of slide through which cold air from the Arctic could whoosh down into states east of the Rocky Mountains (such as Minnesota, Wisconsin and Michigan), Mera wrote in a blog post for the Union of Concerned Scientists, a nonprofit science advocacy organization.

    And there’s more chilling news for states that have yet to feel the polar vortex’s icy breath.

    “There will be another surge of Arctic air associated with the polar vortex heading south next week, which will reinforce the cold across the northern half of the U.S.,” Kines said. The north-central states — the ones who already got clobbered — will probably feel the brunt of this new surge on Monday (Nov. 17). But then, the cold will push eastward, leaving its frosty fingerprints all over the eastern part of the country by Tuesday (Nov. 18) or Wednesday (Nov. 19), Kines said.

    Still, the relative warmth of the Atlantic Ocean waters will make it unlikely that coastal areas of the Northeast will experience heavy snowfall, Kines said. This means people in places like New York and Boston shouldn’t have to get out their shovels just yet, Kines noted, but interior parts of the Northeast, as well as the Appalachians, could see snow.

    If you’re looking to ride out the rest of the fall season somewhere warm, you might want to head for the Sunshine State. Florida, Kines said, is one of the only states in the country that isn’t likely to experience chilly weather over the next week.

    See the full article here.

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  • richardmitnick 5:39 pm on November 12, 2014 Permalink | Reply
    Tags: , , , Weather   

    From LBL: “Latest Supercomputers Enable High-Resolution Climate Models, Truer Simulation of Extreme Weather” 

    Berkeley Logo

    Berkeley Lab

    November 12, 2014
    Julie Chao (510) 486-6491

    Not long ago, it would have taken several years to run a high-resolution simulation on a global climate model. But using some of the most powerful supercomputers now available, Lawrence Berkeley National Laboratory (Berkeley Lab) climate scientist Michael Wehner was able to complete a run in just three months.

    What he found was that not only were the simulations much closer to actual observations, but the high-resolution models were far better at reproducing intense storms, such as hurricanes and cyclones. The study, The effect of horizontal resolution on simulation quality in the Community Atmospheric Model, CAM5.1, has been published online in the Journal of Advances in Modeling Earth Systems.

    “I’ve been calling this a golden age for high-resolution climate modeling because these supercomputers are enabling us to do gee-whiz science in a way we haven’t been able to do before,” said Wehner, who was also a lead author for the recent Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). “These kinds of calculations have gone from basically intractable to heroic to now doable.”

    mw
    Michael Wehner, Berkeley Lab climate scientist

    Using version 5.1 of the Community Atmospheric Model, developed by the Department of Energy (DOE) and the National Science Foundation (NSF) for use by the scientific community, Wehner and his co-authors conducted an analysis for the period 1979 to 2005 at three spatial resolutions: 25 km, 100 km, and 200 km. They then compared those results to each other and to observations.

    One simulation generated 100 terabytes of data, or 100,000 gigabytes. The computing was performed at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility. “I’ve literally waited my entire career to be able to do these simulations,” Wehner said.

    sc

    The higher resolution was particularly helpful in mountainous areas since the models take an average of the altitude in the grid (25 square km for high resolution, 200 square km for low resolution). With more accurate representation of mountainous terrain, the higher resolution model is better able to simulate snow and rain in those regions.

    “High resolution gives us the ability to look at intense weather, like hurricanes,” said Kevin Reed, a researcher at the National Center for Atmospheric Research (NCAR) and a co-author on the paper. “It also gives us the ability to look at things locally at a lot higher fidelity. Simulations are much more realistic at any given place, especially if that place has a lot of topography.”

    The high-resolution model produced stronger storms and more of them, which was closer to the actual observations for most seasons. “In the low-resolution models, hurricanes were far too infrequent,” Wehner said.

    The IPCC chapter on long-term climate change projections that Wehner was a lead author on concluded that a warming world will cause some areas to be drier and others to see more rainfall, snow, and storms. Extremely heavy precipitation was projected to become even more extreme in a warmer world. “I have no doubt that is true,” Wehner said. “However, knowing it will increase is one thing, but having a confident statement about how much and where as a function of location requires the models do a better job of replicating observations than they have.”

    Wehner says the high-resolution models will help scientists to better understand how climate change will affect extreme storms. His next project is to run the model for a future-case scenario. Further down the line, Wehner says scientists will be running climate models with 1 km resolution. To do that, they will have to have a better understanding of how clouds behave.

    “A cloud system-resolved model can reduce one of the greatest uncertainties in climate models, by improving the way we treat clouds,” Wehner said. “That will be a paradigm shift in climate modeling. We’re at a shift now, but that is the next one coming.”

    The paper’s other co-authors include Fuyu Li, Prabhat, and William Collins of Berkeley Lab; and Julio Bacmeister, Cheng-Ta Chen, Christopher Paciorek, Peter Gleckler, Kenneth Sperber, Andrew Gettelman, and Christiane Jablonowski from other institutions. The research was supported by the Biological and Environmental Division of the Department of Energy’s Office of Science.

    See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

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