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SSEC scientists Norm Wood (left), Claire Pettersen (center) and NOAA ASPB scientist Mark Kulie (right). Credit: Bill Bellon<\/p><\/div>\n
\u201cNASA was looking for studies in three areas: process studies, algorithm development and applications,\u201d says SSEC scientist Norm Wood. \u201cEach of us is in a different area, but our research sits at the cross section of all three, so it is very complementary.\u201d<\/p>\n
The PMM is an umbrella mission that consists of a worldwide network of satellites including the Global Precipitation Measurement (GPM<\/a>) Core Observatory, a successor to the Tropical Rainfall Measuring Mission (TRMM<\/a>) satellite. While no longer operational, data from TRMM\u2019s Precipitation Radar and Microwave Imager during its 20-year mission has been crucial to improved understanding of rainfall in the tropics, where much of the driving force behind Earth\u2019s water cycle originates.<\/p>\n While they lead projects that differ in scope and methodology, the three scientists are trying to do something similar, and that is, make a critical breakthrough for understanding snowfall events that will have global implications.<\/p>\n Mountain snowfall processes<\/strong><\/p>\n Two types of observations are available with the GPM mission: passive microwave observations from the multi-channel GPM Microwave Imager (GMI<\/a>) and profiling radar observations from the Dual-frequency Precipitation Radar (DPR<\/a>). Wood\u2019s validation study focuses on the latter of the two. He is looking at orographic snowfall to learn how changes in terrain elevation, shape and form influence snowfall over those areas. Mountain ranges and other types of topography, whether inland or along coasts, can influence the amount and intensity of snowfall.<\/p>\n Up until the age of satellites, many observations of precipitation in the atmosphere have come from ground-based radar systems, forcing the instrument to look up at elevated terrain. However, because the terrain may obscure the field of view, ground instruments are limited as to what they can actually see.<\/p>\n Snow rates retrieved from satellite-borne radar observations and colocated over a map of surface elevation. Credit: Norm Wood<\/p><\/div>\n \u201cBy shifting this scenario to look at these types of systems using radars from space, we get better, more complete, representation of what is going on in the atmosphere over these regions,\u201d says Wood. \u201cAnother important part of our research is to fill in a data gap that exists right now [between our ground and satellite data].\u201d<\/p>\n As the satellite orbits the planet, it passes over different mountain ranges allowing researchers to see them under varying meteorological conditions. The idea is to select certain regions of elevated terrain and observe how the production of snow changes as weather systems flow over the region.<\/p>\n Wood is zeroing in on precipitation efficiency, a measure of how well the available atmospheric water is converted to snowfall. If forecasters can accurately predict how much water will be converted to precipitation in the form of snow, it will serve a range of needs from local agriculture and city planning to climate studies and weather model improvements.<\/p>\n Algorithm development in the Great Lakes<\/strong><\/p>\n Growing up in Michigan\u2019s Upper Peninsula, NOAA ASPB scientist Mark Kulie has seen his share of snowstorms, blizzards and white-outs. He has had a lifelong interest in snowfall patterns, especially in the Great Lakes region. Working with ground-based radars in Marquette, MI, his research, in collaboration with SSEC scientist Claire Pettersen, has isolated a specific type of snow known as convective snow.<\/p>\n NOAA-20 image captured Feb. 12, 2019 showing all of the Great Lakes impacted by lake-effect clouds. Credit: Mark Kulie<\/p><\/div>\n Commonly known as lake or ocean effect snow, this type of snow is typically very shallow \u2014 often forming less than a kilometer from the Earth\u2019s surface \u2014 and results from the interaction of cold air over warmer water. Currently, lake effect snow warnings issued to the public are derived from ground-based radars that can miss the extent, as well as the amount, of accumulation.<\/p>\n Kulie\u2019s interests lie in assessing the accuracy of GPM estimates of convective snow as compared to those obtained from ground measurements and then, improving those estimates to create more robust global convective snow datasets.<\/p>\n \u201cWhat we have learned, though, is that while the GMI sees very distinctive signatures, or characteristics, that are unique to convective snow, the DPR is not as sensitive,\u201d says Kulie.<\/p>\n His research will aim to translate those GMI signatures into snowfall rate estimates and use ground observations to validate and improve DPR estimates for heavier snow. Kulie anticipates this dual-pronged approach will result in better algorithms to monitor global snowfall because observational tools can be employed to check the accuracy of computer-generated snowfall. Improved GPM observations and products will be critical in evaluating snowfall datasets that are produced by computer model simulations. These include reanalysis datasets often used to study snowfall in remote regions that lack routine observations as well as in climate models developed to project future global snowfall amounts.<\/p>\n Just as in the higher elevations, this regional work must also account for differing topographies, like coastlines or lake ice versus open water that can influence precipitation.<\/p>\n \u201cThese lake-effect snow events are very important to regional hydrology around the world,\u201d explains Kulie. In a warming climate with diminishing sea ice and more open water, these types of events may occur more frequently, he says. Kulie\u2019s goal is to create a more robust and long-term, earth monitoring dataset to support better global forecasting and analysis of global trends.<\/p>\n Applications in Norway and Alaska<\/strong><\/p>\n Atmospheric rivers are like conveyor belts of moisture, extending sometimes hundreds of miles, and are commonly associated with intense rainfall along the California coast. But, these well-defined ribbons of anomalously high water vapor flowing in the atmosphere are also responsible for extreme snow accumulation farther north, along the coasts of Norway and Alaska. In fact, they frequently occur in high latitudes and are associated with flooding, highlighting the need for better water resource management in Europe and the US.<\/p>\n![\"\"](\"https:\/\/www.ssec.wisc.edu\/news\/wp-content\/uploads\/sites\/19\/2019\/10\/combined_test_2_log_srate-325x74.png\")
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