辽宁省冬季区域暴雪水汽输送特征

利用1949 - 2015年NCEP/NCAR逐日及月平均资料， 对辽宁省冬季区域暴雪水汽输送特征进行研究， 结果表明： 受冬季风影响， 辽宁省冬季降水水汽主要来自西边界中纬度西风气流的输入， 区域暴雪的发生是经向水汽异常输送的结果， 西风带偏西气流与日本海反气旋性环流西南侧偏南气流在辽宁省交汇是辽宁省区域暴雪产生的主要原因。辽宁省区域暴雪水汽源地主要有西太平洋、 日本海、 东海和黄海， 其中东海、 黄海是直接的水汽源地。日本海高压是辽宁省区域暴雪水汽输送的关键系统， 82.4%的区域暴雪过程海平面气压场有日本海高压存在， 根据其位置和强度可分为偏北型、 偏南型和高压脊型， 不同环流型高压水汽输送强度不同， 区域暴雪分布范围不同。东海、 黄海湿度平流作用和风场辐合作用是辽宁省区域暴雪产生的贡献因子， 不同环流型日本海高压湿度平流作用的贡献不同。

Transporting characteristics of snowstorm water vapor over Liaoning Province in winter

Using the daily and monthly average data of NCAR/NCEP from 1949 to 2015， the characteristics of the snowstorm water vapor transport over Liaoning Province in winter were studied. The results show that： under the influence of winter monsoon， the characteristics of the average winter water vapor transport over the province was that the water vapor mainly came from the middle latitude of the western boundary and there was no water vapor input in the meridional direction of the westerly， however， the occurrence of regional snowstorm was the result of the abnormal transport of water vapor in the meridional direction. There were two main water vapor transport belts. One was the mid-high latitude westerly belt airflow， and the other one was the northern branch of the northeast flow of the anticyclonic circulation over the south side of the Japan Sea. The two water vapor belts converged in Liaoning. Snowstorm water vapor sources mainly included the Western Pacific， the Japan Sea， the East China Sea and the Yellow Sea. The East China Sea and the Yellow Sea were the main and direct sources of water vapor. The Japan Sea high pressure was the key system for the transportation of snowstorm water vapor in Liaoning Province. There was Japan Sea high pressure in sea level pressure field during 82.4% of the snowstorm process in Liaoning Province. According to the location and intensity of the Japan Sea high pressure， it would be divided into northerly， southerly and high-pressure ridge types. Different types of high-pressure water vapor transmission intensity were different， corresponding to the intensity and distribution range of snowstorm in Liaoning Province. The north-north type （high-pressure center was north of 35° N， near or east of 140° E） had the strongest water vapor transmission， and the distribution range of the snowstorm was the largest. The southerly type （high-pressure center was near or east of 30° N， 140° E） had the second strongest water vapor transmission， and the distribution range of the snowstorm was small. High-pressure ridge type （with high-pressure ridges extending southeast or south to the Japan Sea） had the weakest water vapor transmission， and the distribution range of the snowstorm was the smallest. During the occurrence of snowstorm in Liaoning， the East China Sea， as well as the Yellow Sea， was a large area of positive humidity advection， which was the source of water vapor， and Liaoning Province was within the convergence of the wind field. Among them， the northerly area snowstorm was the largest and strongest in the water vapor source area in the north and south of the Yellow Sea. The corresponding wind field convergence area was also largest in range and strongest in strength. The advection of the water vapor in the East China Sea and the Yellow Sea and the convergence of the wind field were the contributing factors for the snowstorm in Liaoning Province.