Convective Weather Forecasting: Implementation of the AutoNowcaster in China
Figure 1 shows an observed squall line passing the Beijing area on July 10, 2006 overlaid by VDRAS winds at the height of approximately 1.3 km plus the one-hour ANC forecast.
The research and development efforts of RAL's Convective Weather Group are aimed at improving short-term (0 – 6 hour) thunderstorm forecasting and bridging the gap in skill between observation-driven expert systems and numerical weather prediction. One of the programs conducted by the Convective Weather Group is a collaborative effort with the Institute of Urban Meteorology (IUM) of the Beijing Meteorological Bureau (BMB) to transfer the NCAR AutoNowcaster (ANC) in support of China's role as host of the 2008 Summer Olympics. As part of this multi-year project, scientists from NCAR and the BMB are studying the local characteristics of thunderstorm initiation and evolution to enable them to modify and tune the ANC algorithms to optimize its performance in the Beijing area. Efforts are also underway to train the IUM staff on thunderstorm nowcasting techniques and the use of the ANC.
FY06 Accomplishments:
The ANC has been installed, and Beijing S-band radar data is being ingested into the system. This ANC installation features the inclusion of Niwot, a new short-term forecasting system which blends observation extrapolation technology and numerical weather prediction model output fields. It also includes the Variational Doppler Radar Assimilation System (VDRAS) which retrieves and assimilates boundary-layer winds and thermodynamics from Doppler radar, surface stations, and sounding data. This marks the first time that VDRAS has been installed in a domain with complex terrain, and preliminary results indicate that it is handling the terrain well. See Figure 1. From an engineering perspective, the ANC, Niwot and VDRAS have successfully assimilated various local data and run in real time. However, several data quality issues have been identified and work is underway to address them. Efforts to build a Beijing area thunderstorm climatology and to develop forecast rules for the ANC have been hampered by the fact that before 2006 the only radar data for the area came from Tianjian, 150 km southeast of Beijing. In anticipation of the 2008 Summer Olympics, scientists from around the world fielded their convective forecast systems at the WMO-sponsored Beijing 2008 Forecast Demonstration Project last summer. NCAR scientists demonstrated the ANC system and participated in the follow-on workshop.
FY07 Plans:
Efforts to correct data quality problems will continue, and further analysis of VDRAS's performance will be conducted. A major focus will be the tuning of the ANC for the Beijing environment. All of this will point toward an important trial run for the forecasting systems in the summer of 2007, one year before the Olympics begin in Beijing