PLEASE POST

 

MMM       SEMINAR      NCAR

 

 Climatology, Analysis, and Prediction

of Convection in Beijing Area

 

Yingchun Wang

Institute of Urban Meteorology

Beijing Meteorological Bureau, Beijing China

                         

Providing operational short-term prediction and warning of severe weather events is an important responsibility of the Beijing Meteorological Bureau (BMB).

 During the Beijing 2008(B08) Olympic period, heavy rainfall and thunderstorms can occur frequently and have a significant impact on the Olympics game. BMB is the official provider of the Olympic weather services. In order to provide accurate and timely weather prediction for the Olympics, it is necessary to perform

studies on climatology, analysis, and prediction of severe weather events. Using the Beijing C-band radar data (time period is June, July, and August from

 2003 to 2005) and surface stations data during warm seasons (from 1994 to 2005), we have performed climatology analysis of convective storm cases. We found that accurate prediction of convection was very challenging because of the complex terrain surrounding Beijing. In order to enhance BMB's ability in short-range convection forecasting, we have

performed studies of important severe weather events. On 10 July 2004, a severe local heavy rainfall event took place in the metropolitan area of Beijing. Six-hour accumulated rainfall ending at 1200 UTC 10 July exceeded 125 mm. Many parts of the Beijing City were flooded, causing severe traffic jam during the afternoon rush hour. Satellite imagery showed that this heavy rainfall event was associated with the formation and development of a meso-ß-scale (50 km x 120km) convective system. In this study we performed numerical experiments using the WRF model at cloud-resolving (4 km) resolution. We found that the NCEP Global Forecast System (GFS) analysis at 1200 UTC 9 July was too dry in the boundary layer and too stable over the Beijing area. Much improved result was obtained when the precipitable water measurements from the eight BMB ground-based GPS stations were assimilated together with upper-air, surface and AWS data. Looking into the future, BMB is collaborating with NCAR to d

evelop operational Beijing Nowcasting System for 0-2 hr convective weather forecast based on the extrapolation and radar retrievals and to use mesoscale prediction with WRF-ARW model for 3-12 hr convective weather prediction, including Beijing local WRF-Var data assimilation (GPSTPW/AWS/Wind profiler), Rapid Update Cycle (3hr update, 9km resolution), and using Beijing data (landuse, terrain etc.) to fine tune WRF and land-surface model parameters.

 

PLEASE NOTE LOCATION  

 

Thursday, 29 June 2006, 3:30 PM

Refreshments 3:15 PM

NCAR-Foothills Laboratory

3450 Mitchell Lane

Bldg 2 Auditorium (Rm. 1001)