基于GPS资料调整中尺度模式湿度场的应用研究

Study of the Adjustment to the Humidity Field from Mesoscale Model Based on GPS Data

利用长三角洲地基GPS观测网中124个站点的可降水量（PWV）资料，对影响长三角洲降水的“0716”号热带风暴“罗莎”进行WRF模式湿度场调整试验。结果表明，经GPS／PWV资料调整后，上海宝山站的水汽混合比从地面至模式层顶均得到了相应的调整，且模式下层的调整幅度大于模式上层，在300hPa以下模式各层相对湿度调整幅度比较均匀，基本在5％～8％；调整后的850hPa水汽通量大值中心范围缩小．数值也有所减小，水汽通量中心北侧的水汽输送带明显南压，一方面表明江苏北部水汽输送减少，不利于降水，另一方面伴随水汽通量中心南侧的水汽输送带的略微北抬，使上海、杭州湾一带水汽通量梯度增大，有利于降水，与实况江苏北部降水较小、上海及浙北降水较大相吻合。综上所述，利用长三角洲地基GPS观测网资料对WRF模式湿度场调整可使其更好地反映湿度的局地变化特征，更为接近真实大气的水汽分布。

The adjustment to the humidity filed of the ＂0716 Tropical storm Krosa＂ in WRF model is done based on the precipitation water va- por（PWV） data of 124 stations from GPS network in Yangtz River Delta region. The results showed that after GPS/PWV data adjustment, water vapor mixing ratio of Shanghai Baoshan station from the surface layer to the top layer of model are adjusted accordingly, and the adjustment of lower layer is greater than upper level, the adjustment of relative humidity for layers lower than 300 hPa is relative even, which are between 5 to 8% basically ; Both the value and cover of the vapor flux center at 850 hPa are decreased after the adjustment, and the vapor transport belt at the north side of the vapor flux center is clearly moving southward. It indicates that the water vapor transport in northern Jiangsu is reduced on one hand which is bad for rainfall, on the other hand, the slightly northern moving of the water vapor transport belt in the south side of the water va- por flux center increases the slope of vapor flux gradient in Shanghai and Hangzhou bay, which is good for the rainfall. In summary, using ground-based GPS network data in Yangtz River Delta region to adjust the humidity field of WRF model would lead to better representativeness of local humidity variations and closer to the true distribution of atmospheric water vapor.