江西省域蒸发皿蒸发量变化特征及其成因

为了探讨气候变化对陆面水文过程的影响，该文利用江西省79个气象站1960－2005年的常规观测资料为基础，结合修正的Penman公式，得出了日照百分率、风速、实际水汽压、最低温度、最高温度变化对蒸发皿年蒸发量变化的贡献。结果表明：在过去46 a中，全流域的平均蒸发皿年蒸发量呈显著下降趋势，其速率为-4.57 mm/a；日照百分率和风速的减小是导致流域平均蒸发皿年蒸发量下降的主要因子，其贡献分别为-2.06、-2.58 mm/a，实际水汽压的减小、最低温度和最高温度的升高导致流域平均蒸发皿年蒸发量上升，但作用相对较小，分别为0.12、0.50、0.30 mm/a，各占观测的蒸发皿年蒸发量变化趋势的45.08%、56.46%、-2.63%、-10.94%、-6.57%。因此，影响江西省蒸发皿年蒸发量变化的气候因子的主次关系为：风速＞日照百分率＞最低温度＞最高温度＞实际水汽压。

Change in pan evaporation and its driving factors in Jiangxi Province

In order to discuss the influences of the climate changes on the land-surface hydrological processes, in this paper, observation data from 79 weather stations of Jiangxi Province from 1960 to 2005 were analyzed, the attributions of changing annual pan evaporation due to percentage of sunshine duration, wind speed, actual vapor pressure, minimum temperature and maximum temperature were evaluated with Penman equation. It showed that the annual pan evaporation in Poyang Lake Basin as a whole had continuously decreased at a rate of -4.57 mm/a in the past 46 years. The major factors for annual pan evaporation decrease were reduced sunshine hours and weakened wind speed, with their attributions of -2.06 mm/a and -2.58 mm/a, respectively, whereas decrease in atmospheric vapor pressure and the increases in both the minimum and maximum temperatures contributed to the relatively smaller annual pan evaporation increase, with their attributions of 0.12 mm/a, 0.50 mm/a and 0.30 mm/a, respectively. In summary, the relative contributions of the five environmental factors to the observed pan evaporation variations were listed in the order of importance: wind speed (56.46%)> percentage of sunshine duration (45.08%)>minimum temperature (-10.94%)> maximum temperature (-6.57%) >vapor pressure (-2.63%).