Jiangsu Moisture Characteristics Analysis in Different Weather Background of Plum Flood Season

By using June and July daily ERA reanalysis data (0.75 ° * 0.75 °)from 2010 to 2014, observation data of rainfall on each station and perceptible water vapor (PWV) data from GPS monitoring data in Jiangsu from 2010 to 2015, the vapor characteristics in different weather backgrounds of flood seasons are studied by contrastive analysis methods. The water vapor characteristics of different precipitation levels, distribution of water vapor characteristics and water vapor source in different area storm of Jiangsu province were analyzed. The analysis results show that the vapor characteristic quantities have different functions in different weather backgrounds. Specific humidity and PWV can be used to determine amount of precipitation, and the judgment standards of different rainfall levels corresponding to specific humidity and PWV value are given in the paper. The average value of PWV is about 60mm when the heavy rain happens in plum flood season, which is more 10mm than the value in weak precipitation. Another, the average value of PWV is 30-33mm in no rain. PWV’s spatial distribution presents obviously difference in Jiangsu different regional precipitation. The heavy rain area is located in the north of Jiangsu province when the whole PWV value over the province is high, while the heavy rain region only occurs in the area of high PWV when PWV value is just high in the south of Jiangsu. Heavy rain is located coincidently on the region where high relative humidity and high moisture content overlaps. The distribution of humidity and vapor content is different corresponding to whether the heavy rain drops in the north or the south area. On this basis, the structure diagrams of situation and vapor during rainstorm in the Jiangsu different region are established.