南雄近55年降水量与蒸发量的变化特征

Characteristics of Rainfall and Evaporation Amount of Nanxiong in the Past 55 Years

利用广东省南雄国家基准气候站1955—2010年的降水量和蒸发量资料,采用距平和累积距平曲线统计方法,对南雄降水量、蒸发量的变化及其对干燥度的影响进行了分析。结果表明:南雄站降水量年际变化明显,其中1955—1960及1966—1974年累积距平为负值,1961—1965及1975年至今为正值;春、秋季距平曲线较一致,夏、冬季降水量呈偏多态势,但2000年后降水减少,趋于历年平均。对年蒸发量来说,1955—1965年变化不明显,1966—1999年呈显著上升趋势,2000—2010年则明显趋于下降。各季蒸发量除春季外均与年蒸发量趋势一致,春季1955—1999年变化不明显,2000年起呈下降趋势。受此影响,1955—1999年南雄市气候总体趋于更加湿润,但2000—2010年南雄市降水偏少,蒸发显著下降,气候处于更加湿润阶段。

With the data of rainfall and evaporation amount of a national base climate observation station in Nanxiong, Guangdong province and the methods of anomaly and accumulative anomaly, we studied the variation of rainfall and evaporation amount and its effect on dryness. As shown in the result, the interannual rainfall variation of Nanxiong is significant, and the accumulative anomaly is negative from 1955 to 1960 and from 1966 to 1974 while being positive from 1961 to 1965 and from 1975 till the present. The anomalous curves of the spring and autumn are quite consistent while those of the summer and winter are with multiple morphology, with the rainfall tending to decrease after 2000 and coming close to the average over the years. For the annual amount of evaporation, the variation is insignificant from 1955 to 1965, rises sharply from 1966 to 1999, and drops significantly from 2000 to 2010. Except for spring, seasonal evaporation tends：to be consistent with the annual evaporation, the variation in spring is not significant from 1955 to 1999 but shows a decreasing trend from 2000. Owing to it, the climate of Nanxiong is generally wetter from 1955 to 1999. The precipitation decreases from 2000 to 2010 and the evaporation drops significantly, leading to a much wetter climate.