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利用WRF-3DVAR系统同化常规探空资料及成都4个GPS测站的可降水资料,对2008年9月23～25日一次川西暴雨进行一系列同化试验。结果表明,选用合理的物理过程、积分步长和初始条件,WRF模式可以较好地模拟此次暴雨过程;同化可以改善暴雨落区和强度的预报,同化GPS可降水资料可有效地调节局地及水汽输送下游地区暴雨预报,对北川地区的强降水中心强度及位置预报较好,同化探空资料对雨带形状描述接近实况;同化GPS可降水资料对初始场的湿度场影响明显,而对其他变量场的影响相对较弱;2种资料的单独及同时同化,都改善了预报场的动力结构(垂直速度),有效地减少了spin-up时间,使得模式在积分初期就能模拟出与实况相近的动力结构;同化试验的温度预报场随时间误差增大,这可能与降水的触发有关。
Using WRF-3DVAR system to assimilate conventional radiosonde data and precipitable data from 4 GPS stations in Chengdu, a series of assimilation tests on a heavy rainstorm in western Sichuan from September 23 to 25, 2008, were conducted. The results show that the WRF model can simulate the rainstorm process well with reasonable physical process, integral steps and initial conditions. Assimilation can improve the prediction of rainstorm area and intensity, and assimilate GPS data of precipitation to effectively adjust the local And rainstorm forecast in the downstream area of water vapor transport, the forecast of intensity and location of heavy precipitation center in Beichuan region is good, and the assimilation of sounding data to the shape of rainband is close to the actual situation; assimilating GPS precipitable data has a significant impact on the initial field humidity field, The effects of field on other variables are relatively weak. The separate and simultaneous assimilation of the two kinds of data improves the dynamic structure (vertical velocity) of the prediction field and effectively reduces the spin-up time so that the model can simulate The dynamical structure with similar live conditions; the temperature forecast field of assimilation test increases with time, which may be related to the triggering of precipitation.