The Understanding Severe Thunderstorms and Alberta Boundary Layers Experiment (UNSTABLE) 2008

Bulletin of the American Meteorological Society - Tập 92 Số 6 - Trang 739-763 - 2011
Neil M. Taylor1, David Sills2, John Hanesiak3, Jason A. Milbrandt4, Craig D. Smith5, G. S. Strong6, S. Skone7, Patrick J. McCarthy8, Julian C. Brimelow3
1Hydrometeorology and Arctic Lab, Environment Canada, Edmonton, Alberta, Canada
2Cloud Physics and Severe Weather Research Section, Environment Canada, Toronto, Ontario, Canada
3Department of Environment and Geography, Centre for Earth Observation Science, University of Manitoba, Winnipeg, Manitoba, Canada
4Numerical Weather Prediction Research Section, Environment Canada, Dorval, Quebec, Canada
5Climate Research Division, Environment Canada, Saskatoon, Saskatchewan, Canada
6Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
7Department of Geomatics Engineering, University of Calgary, Calgary, Alberta, Canada
8Prairie and Arctic Storm Prediction Centre, Environment Canada, Winnipeg, Manitoba, Canada

Tóm tắt

Severe thunderstorms are a common occurrence in summer on the Canadian prairies, with a large number originating along the Alberta, Canada, foothills, just east of the Rocky Mountains. Most of these storms move eastward to affect the Edmonton–Calgary corridor, one of the most densely populated and fastest-growing regions in Canada. Previous studies in the United States, Europe, and Canada have stressed the importance of mesoscale features in thunderstorm development. However, such processes cannot be adequately resolved using operational observation networks in many parts of Canada. Current conceptual models for severe storm outbreaks in Alberta were developed almost 20 years ago and do not focus explicitly on mesoscale boundaries that are now known to be important for thunderstorm development. The Understanding Severe Thunderstorms and Alber ta Boundary Layers Experiment (UNSTABLE) is a field and modeling study aiming to improve our understanding of the processes associated with the initiation of severe thunderstorms, to refine associated conceptual models, and to assess the ability of convectivescale NWP models to simulate relevant physical processes. As part of UNSTABLE in 2008, Environment Canada and university scientists conducted a pilot field experiment over the Alberta foothills to investigate mesoscale processes associated with the development of severe thunderstorms. Networks of fixed and mobile surface and upper-air instrumentation provided observations of the atmospheric boundary layer at a level of detail never before seen in this region. Preliminary results include the most complete documentation of a dryline in Canada and an analysis of variability in boundary layer evolution across adjacent forest and crop vegetation areas. Convective-scale NWP simulations suggest that although additional information on convective mode may be provided, there is limited benefit overall to downscaling to smaller grid spacing without assimilation of mesoscale observations.

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Bulletin of the American Meteorological Society

Tập 92 Số 6

739-763

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