Event Title

Changes in Winter Precipitation Regime over China during the land half Century

Location

Eccles Conference Center

Event Website

http://water.usu.edu/

Start Date

4-20-2010 10:20 AM

End Date

4-20-2010 10:40 AM

Description

Significant trends in annual precipitation and widespread warming in China have been documented. In the winter months over Southeast China, where snow is commonplace but rarely accumulates, the climatological 0°C surface isotherm generally defines the southern boundary of the snowfield. Therefore, a warming climate will (a) modify the southern boundary of the snowfield and (b) potentially alter the snow-rain ratio. Using recently released daily precipitation and temperature gridded observations from the Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation (APHRODITE) and the ERA40/Interim reanalyses, this presentation investigates historical winter precipitation change in China. Since snowfall observations are largely unavailable for Southeast China, snowfall amounts were estimated using a rain-snow threshold temperature (RST) method which was subsequently verified by in-situ and satellite observations of snow depth, snow cover, and snow water equivalent. The composite analysis reveals a decrease in snowfall totals which are accompanied by an increase in rainfall; this change corresponds with the northward retreat of the 0°C surface isotherm. Atmospheric circulation analysis indicates a lower tropospheric warming with increased moisture over Southeast China, consistent with previous studies. Moreover, we observed an increase in the convergence of water vapor flux which sustains the increase in precipitation; this is accompanied by the suppression of snowfall due to the lower tropospheric warming. An addition approach to substantiate the RST method was modeling the snow-rain ratio with the Weather Research and Forecasting Model (WRF-ARM). The results are consistent with those estimated from the observations.

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Apr 20th, 10:20 AM Apr 20th, 10:40 AM

Changes in Winter Precipitation Regime over China during the land half Century

Eccles Conference Center

Significant trends in annual precipitation and widespread warming in China have been documented. In the winter months over Southeast China, where snow is commonplace but rarely accumulates, the climatological 0°C surface isotherm generally defines the southern boundary of the snowfield. Therefore, a warming climate will (a) modify the southern boundary of the snowfield and (b) potentially alter the snow-rain ratio. Using recently released daily precipitation and temperature gridded observations from the Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation (APHRODITE) and the ERA40/Interim reanalyses, this presentation investigates historical winter precipitation change in China. Since snowfall observations are largely unavailable for Southeast China, snowfall amounts were estimated using a rain-snow threshold temperature (RST) method which was subsequently verified by in-situ and satellite observations of snow depth, snow cover, and snow water equivalent. The composite analysis reveals a decrease in snowfall totals which are accompanied by an increase in rainfall; this change corresponds with the northward retreat of the 0°C surface isotherm. Atmospheric circulation analysis indicates a lower tropospheric warming with increased moisture over Southeast China, consistent with previous studies. Moreover, we observed an increase in the convergence of water vapor flux which sustains the increase in precipitation; this is accompanied by the suppression of snowfall due to the lower tropospheric warming. An addition approach to substantiate the RST method was modeling the snow-rain ratio with the Weather Research and Forecasting Model (WRF-ARM). The results are consistent with those estimated from the observations.

https://digitalcommons.usu.edu/runoff/2010/AllAbstracts/22