重庆市参考作物蒸散量及湿润指数变化研究

利用1960—2008年重庆市34个气象站点的逐日降水、气温、气压、空气相对湿度、日照时数等气象要素资料，采用FAO推荐的彭曼—孟蒂斯公式，以日为单位，计算出各站点近49 a的参考作物蒸散量和湿润指数；采用线性趋势法、ArcGIS反距离权重空间插值法、Mann-Kendall突变检验法和相关分析法等方法，分析了1960—2008年重庆市的参考作物蒸散量和湿润指数的时空分布和变化趋势。结果表明:（1）重庆市年均参考作物蒸散量的空间分布差异显著，表现为由渝东南地区向渝东北地区和渝中西部地区增加的趋势。时间上，1960—2008年总体呈现下降趋势，但有阶段性的差异；（2）年均湿润指数空间分布差异较大，以渝东南的酉阳湿润指数最高，并由渝东南地区向渝东北地区和渝中西部地区递减。年均湿润指数时间分布总体呈现上升趋势，但阶段性有差异，突变年为1979年；（3）重庆市地表湿润指数与降水量、相对湿度呈现显著的正相关关系，与平均气温、最高气温、平均风速、日照时数以及参考作物蒸散量呈负相关。

Reference Crop Evapotranspiration and Surface Humidity Index in Chongqing City

Based on the climatic factors such as daily maximum temperature, minimum temperature, precipitation, relative humidity, wind speed and sunshine duration measured daily at 34 stations from 1960 to 2008 in Chongqing City, potential evaporation was calculated for the region using the United Nations Food and Agriculture Organization (FAO) Penman-Monteith model, which allows the calculation of the surface humidity index for the location of each station. The spatial and temporal distribution and change trend of reference crop evapotranspiration and wetness index in Chongqing City from 1960 to 2008 were analyzed by using the linear regression, inverse distance weighted methods in ArcGIS 10.0, Mann-Kendall mutation test, correlation analysis method. The results indicated that: (1) spatially, the reference crop evapotranspiration appeared as geographical difference obviously, which exhibited a gradual increased from southeast to northeast and mid-west of Chongqing City, and decreased timely, but was different with stages; (2) the spatial pattern of the change of humidity index of the study region showed clear difference in different regions, with the humidity index decreasing from southeast to southwest and northeast, and highest in Youyang station, the annual humidity index distributed a rising trend, and the mutation year is 1797, but different in stages; (3) the humidity index had the positive correlations with precipitation and relative humidity, but had the negative correlations with average temperature, maximum temperature, wind speed, sunshine duration and potential evaporation.