Monitoring the 2008 cold surge and frozen disasters snowstorm in South China based on regional ATOVS data assimilation

In January 2008, South China experienced extremely low temperatures, heavy snowstorms, and severe frosts (2008 Frost Disaster, for short), which led to (partial) failures of observations from ground stations and ground radars resulting in a lack of necessary emergency information. To compensate for the failure of ground observations and to provide timely disaster information, the National Satellite Meteorological Center of China (NSMC) established a snow storm monitoring system for the 2008 Frost Disaster, which was based on the WRF Three Dimension Variational Assimilation and Forecast system (with NOAH as the land surface sub-process model) cooperatively developed by NSMC and the National Center for Atmospheric Research (NCAR), US. This system made full use of ATOVS and NCEP data to provide estimates of snow water equivalent every 6 hours during the storm. In this study, the ATOVS assimilation based snowstorm monitoring scheme was explored in detail, while the modeled results with and without ATOVS assimilation were compared against related observations. Results showed that the coupling of ATOVS assimilation into the proposed monitoring system evidently delineates weather characteristics of the snowstorm process more accurately, and demonstrated the feasibility of the system for snowstorm monitoring and forecasting. Through theoretical analyses and case discussion, this study proposes a reliable and practicable scheme to provide timely and accurate information on snow spatial distribution and temporal development for disaster mitigation, and illustrates a new application of ATOVS data.