Analysis on Water Vapor Condition of a Heavy Rainstorm Process in Shenyang in 2013
The water vapor condition of a short-time heavy rainstorm in Shenyang on 16 August 2013 was analyzed in detail by using the Micaps data,the analytic fields of mesoscale numerical mode data,conventional observation data and automatic meteorological observing data.The results indicated that water vapor content below 850 hPa accounted for more than 80% of the whole layer water vapor content.The change of ground specific humidity in rainstorm area presented increasing fast firstly and then decreasing.The maximum of specific humidity was not corresponding to the strongest moment of the heavy rain.Before the heavy rain occurrence,the distribution of humidity on surface was uneven in Shenyang,and water vapor transported mainly in north-south direction.Wind direction changed fast at the low level,which caused humidity increasing suddenly,thereinto,it was the main contribution of the south wind component.The vertical water vapor was transported from 850 hPa to upper level,the intensity of transportation falled into a decline below 850 hPa.With the heavy rain occurring,the vertical water vapor transportation changed,the lower the height,the higher the intensity of transportation,and water vapor flux reduced rapidly on surface in U and V direction.After the heavy rain,water vapor transportation on surface and upper layer changed.There was a corresponding relationship between the atmospheric precipitable water and precipitation.The atmospheric precipitable water in heavy rainstorm area primarily depended on the vapor flux convergence in horizontal direction,while vapor flux convergence was largely decided by convergence of horizontal wind.