Moisture Source Analysis of a Heavy Snowstorm in Southern Shandong Province Based on Lagrange Method
By the Lagrange trajectory model(HYSPLIT),E-P diagnostic method and moisture source attribution method,the moisture sources and transport paths of a backflow heavy snowstorm in southern Shandong Province in 2015 are studied.The results show that there were three major water va-por paths affecting the snowstorm.One was the backflow path,which entered into southern Shandong along with the mid-and low-level backflow cold air through the Bohai Sea and Yellow Sea.Another was the southern branch path,which entered into southern Shandong northward along with the southwest air-flow through the South China and Central China.And the third was westward path,which entered into southern Shandong together with the westerly airflow from the east side of the Loess Plateau.Quantitative analysis of the converged source areas shows that there were six water vapor sources of the backflow snow-storm,including the Bohai Sea and Yellow Sea region,the central and northern East China,the central and southern China,the South China Sea,the south and the north of Asian continent.The contributions of different sources to the heavy snowstorm are compared and the results are as follows;the central and southern China region and the Bohai Sea and Yellow Sea region contributed the most,which was attribu-ted to their higher water vapor intake in the source area.The initial water vapor intake in the central and northern East China region was small,but the final water vapor contribution cannot be ignored because of the low water vapor loss along the way and the high precipitation conversion rate in the target region.Al-though the initial water vapor intake in the south and the north of the Asian continent was significantly higher than that of the central and northern East China,the actual water vapor contribution of the south and the north of the Asian continent was lower than that of the central and northern East China due to the high evaporation in the air parcel along the way.The contribution of water vapor in the South China Sea was the smallest,which was caused by higher loss of water vapor and the lower intake of water vapor at the beginning.
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