地基微波辐射计在遥测大气水汽特征及降水分析中的应用

Remote Sensing of Precipitable Water Vapor Features and Application in Precipitation Analysis by Using Ground-based Microwave Radiometer

利用山西太原的地基多通道微波辐射计资料,结合探空和自动站降水数据,研究不同天气背景下大气水汽总量(V)、积分液态水含量(L)和水汽密度(VD)的分布特征和演变规律,并探讨微波辐射计资料在降水分析中的应用。结果显示:1—6月V、L呈增大趋势,非降水日V、L相对较小,降水日,V和L明显增大;VD垂直廓线特征显示,1—6月VD均呈逐渐增大趋势,最大值出现在距地面500 m高度以内,降水日VD值明显大于非降水日,且VD随高度升高有减小趋势,降水天气背景下水汽主要在1~2 km高度范围内增大积聚,且高值区厚度较大;V的日变化曲线呈现2个峰值,分别出现在早晨(06—08时,北京时,下同)和夜间(22—23时),谷值一般出现在午后(12—16时);初夏季节降水前1 h,V、L通常会有明显增大,一般V>10 mm,L>0.3 mm,V、L的平均跃增量分别为7 mm和0.6 mm,V、L的迅速增大预示着测站上空水汽的迅速聚集,可作为降水可能发生的指示因子。

Characteristics of Precipitable Water Vapor（ V）,Liquid Water Path（ L）,and vapor density（ VD） under non-rainy and rainy weather conditions in the central area of Shanxi Province were studied using the multi-channel microwave radiometer remote sensing combined with Taiyuan sounding and automatic meteorological station data,and the application of the microwave radiometer remote sensing data in precipitation analysis was discussed. Results show that both V and L presented an increasing trend from January to June. The value of V and L was relatively lower under non-rainy weather condition,while V and L increased obviously on rainy days.The VD vertical profile characteristics showed a trend of gradually increasing from January to June,and the maximum generally appeared under the 500 m height. The values of VD were obviously larger on rainy days than those on non-rainy days. The VD vertical profiles showed decreasing trend with height increase. The water vapor mainly increased and accumulated from 1 to 2 km on rainy days,and the larger value layer was thicker. Diurnal variation of V showed two peaks which appeared from 06：00 to 08：00 in the morning and from 22：00 to 23：00 at night,and the valley generally appeared in the afternoon（12：00-16：00）. The statistical analysis of variation characteristics about V and L before and after rainfall process was done,and the results showed V and L increased quickly one hour before rainfall process,and V was generally greater than 10 mm and L was greater than 0. 3 mm,and the average increments of V and L were 7 mm and 0. 6 mm,respectively,which indicated the rapid accumulation of water vapor over the observation station and a high probability of precipitation,it can be used as a possible indicator factor.