2012年广东省前汛期气候特点及其成因初步分析

2012年前汛期(4～6月),我省平均气温较常年偏高0.9℃,降水量较常年偏多13.2%。前汛期主要气候特点表现在:4月降水异常偏多71.4%,5月下旬至6月中旬的龙舟水明显偏少,强对流天气频发,热带气旋影响偏早、总体灾情轻。大气环流仍然表现为对前期结束的拉尼娜事件的滞后响应,西太平洋副高强度偏弱、面积偏小、西伸脊点偏东,有利于北方弱冷空气南下与异常旺盛的西南暖湿气流在华南地区汇合,是前汛期内降水偏多的主要原因。

Climate Characteristics and the Causal Analysis for the First Flood Season in 2012

For the fist flood season of 2012 （April-June） in Guangdong province, the average temperature is 0.9 ℃ high- er and the precipitation is 13.2% more than the average of the same period. In April, the rainfall is anomalously 71.4% more, while the dragon-boat precipitation （late May to mid June） is significantly less than climate average. Even with high fre- quency of convective weather, earlier influence of tropical cyclones, Guangdong suffers less from meteorological disasters over- all. Atmospheric circulation showed a delay response to the just-ended La Ni？ a event with weaker and smaller west pacific subtropical high and more eastward west-ridge point. These are favorable for the southward movement of cold air mass to con- verge with southwest moist and warm air, leading to more precipitation in the first flood season.