南海西南季风强度与茂名降水的关系

Relationship Between the Intensity of Southwest Monsoon in South China Sea and Precipitation in Maoming

利用NECP/NCAR再分析资料和茂名地区观测站1974—2013年降水资料,运用相关分析等统计方法,探讨近40年来西南季风强弱与茂名降水的关系。结果表明:南海西南季风强度对茂名汛期、年降水量的影响有非对称性,南海西南季风强,茂名汛期、年降水较常年偏多;西南季风弱,茂名降水不确定,各月规律不同。西南季风强度与茂名某些月份尺度的相关性比季、年尺度的相关性较好,特别是冬季月份。近40年茂名暴雨日分布表现为单峰型,暴雨集中在5—9月,7月为峰值;各季风年极端降水多发的月份不同,强季风年为4—9月、正常年为5—8月、弱季风年为5—9月。强季风年极端降水发生的概率大于其它年份,正常年极端降水发生的概率较小。

Using NCEP/NCAR reanalysis and precipitation data of observation stations in the Maoming area from 1974 to 2013 and statistical methods, such as correlation analysis, we study the relationship between the intensity of Southwest Monsoon and the precipitation in the 40 years. The result is shown as follows. The intensity of Southwest Monsoon in the South China Sea has asymmetric effect on the raining season and annual rainfall amount in Maoming; when the former is strong, the latter is anomalously stronger, and when the former is weak, the latter is uncertain and varies from month to month. The Southwest Monsoon intensity is better correlated with the monthly scale in some months, especially winter months, than with the seasonal and annual scales. Over the 40 years, the number of heavy rain days distributes in a unimodal way and heavy rain concentrates in May to September and peaks in July. The months in which annually extreme precipitation also varies in different monsoon years. For the years of strong, normal and weak monsoon, it occurs in April to September, May to August and May to September, respectively. The probability for annually extreme rainfall to occur is larger in the years of strong monsoon than in the years of normal and weak monsoon and it is relatively small in the years of normal monsoon.