THE DESIGN OF HOURLY UPDATE BJ-RUC SYSTEM FOR IMPROVING CONVECTIVE PRECIPITATION FORECASTING
TONG Wen-xue
LI Gang
SUN Juan-zhen
Abstract：This study shows an improved version of Beijing Rapid Updated Cycling (BJ-RUC) forecast system with hourly update frequency and its impact on quantitative precipitation forecast (QPF).The new BJ-RUC system adopted the two-step assimilation strategy with additional improvements.Synoptic and convective observations are assimilated in different steps to extract both large-scale and convective-scale information from observations.The new system was tested with four convective cases in Beijing area during summer 2009.A detailed analysis on how the new system impacts on convective-scale QPF was conducted using a squall line case in Beijing area on 23 July 2009.The improvement in the new system results in improved QPF throughout most of the 12 h forecast period.The diagnoses of the analysis fields show that the new system is able to preserve key convective-scale as well as large-scale structures that are consistent with the development of the weather system.This study provides a prototype for operational short-term prediction of the local convective weather system.
Keywords：data assimilationhourly rapid update cyclingQPF3DVARradartwo-step assimilation
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 177-187 )