An enhanced optical flow technique for radar nowcasting of precipitation and winds

An enhanced optical flow technique for radar nowcasting of precipitation and winds AbstractThe atmospheric state evolution is inherently highly complex three-dimensional problem which Numerical Weather Prediction (NWP) models attempt to solve. Although NWP models are being successfully employed for medium and long range forecast, their short duration forecast (or nowcast) capabilities are still limited due to model initialization challenges. On the lower end of the complexity scale, nowcasting by extrapolation of two-dimensional weather radar images has long been the most effective tool for nowcasting precipitation. Attempts are being made to take advantage of both approaches by blending extrapolation and numerical model forecasts. In this work a different approach is presented, relying on the additional radar Doppler wind information and a simplified modeling of basic physical processes. Instead of mixing the outputs of different forecasts as in blended approaches, the idea behind this study is to combine extrapolation and precipitation modeling in a new technique with a higher level of complexity respect to conventional nowcasting methods, although still much simpler than NWP models. As a preliminary step the Variational Doppler Radar Analysis System (VDRAS) is used to provide an initial analysis exploiting all the available dual-polarization and Doppler radar observations. The rainwater and wind fields are then advected using an optical flow technique, subject to simplified physical interactions. As a result precipitation and wind nowcasting is obtained, and successively validated up to one hour lead time, showing potential improvement upon standard extrapolation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Atmospheric and Oceanic Technology American Meteorological Society

An enhanced optical flow technique for radar nowcasting of precipitation and winds

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Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0426
D.O.I.
10.1175/JTECH-D-17-0110.1
Publisher site
See Article on Publisher Site

Abstract

AbstractThe atmospheric state evolution is inherently highly complex three-dimensional problem which Numerical Weather Prediction (NWP) models attempt to solve. Although NWP models are being successfully employed for medium and long range forecast, their short duration forecast (or nowcast) capabilities are still limited due to model initialization challenges. On the lower end of the complexity scale, nowcasting by extrapolation of two-dimensional weather radar images has long been the most effective tool for nowcasting precipitation. Attempts are being made to take advantage of both approaches by blending extrapolation and numerical model forecasts. In this work a different approach is presented, relying on the additional radar Doppler wind information and a simplified modeling of basic physical processes. Instead of mixing the outputs of different forecasts as in blended approaches, the idea behind this study is to combine extrapolation and precipitation modeling in a new technique with a higher level of complexity respect to conventional nowcasting methods, although still much simpler than NWP models. As a preliminary step the Variational Doppler Radar Analysis System (VDRAS) is used to provide an initial analysis exploiting all the available dual-polarization and Doppler radar observations. The rainwater and wind fields are then advected using an optical flow technique, subject to simplified physical interactions. As a result precipitation and wind nowcasting is obtained, and successively validated up to one hour lead time, showing potential improvement upon standard extrapolation.

Journal

Journal of Atmospheric and Oceanic TechnologyAmerican Meteorological Society

Published: Oct 24, 2017

References

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