A Frequent-updating High-resolution Analysis System Based on Radar Data for the 2008 Summer Olympics

In preparation for the 2008 summer Olympics, Beijing has upgraded its mesoscale-observing network. Among the observing systems are 4 Doppler radars, soundings at 6- hour intervals from 5 sites, 136 automated weather stations and 30 GPS receivers. A Forecast Demonstration Project (B08FDP), focused on 0-6 hour prediction of convective weather, is planned to take place during the summer of 2008. The demonstration will include state-of-the-art forecast systems from Beijing, Hong Kong, Australia, Canada and the United States.

Beijing Meteorological Bureau (BMB) of China is collaborating with the National Center for Atmospheric Research (NCAR) to transfer the convection nowcasting technology of NCAR to BMB to enhance its capability of the very-short-term forecasting of convective weather. Other than a nowcasting system that aims at producing precipitation nowcasting, the technology transferred to BMB also includes a high-resolution Doppler radar analysis system called VDRAS (Variational Doppler Radar Analysis System). VDRAS is a 4D-Var (4-dimensional variational) based system that assimilates observations from multiple Doppler radars and produces 3-km wind, temperature, and humidity analysis with an update frequency of ~20 min. Recently, VDRAS analysis experiments have been conduced on four Beijing convective cases using data collected in summer 2006 and a domain covering radar coverage areas of both Beijing and Tianjin S-band. High-resolution convergence, cooling/heating, and humidity features are obtained in these case studies. Further analysis of these features is underway to examine the correlation of these features with convective initiation and development. The VDRAS analyzed wind is compared with that from a wind profiler and some statistical differences are being computed. Results of these statistics will be presented during the conference.