元谋干热河谷地区ET_0特征及其影响因子分析

Trend of reference crop evapotranspiration and its main meteorological impact factors in Yuanmou dry-hot valleys during the last 57 years

为了探索近57年(1956-2012年)元谋干热河谷地区不同时间尺度参照作物腾发量ET0特征,该文以实测的日和年微气象资料为基础,采用联合国粮农组织(FAO)推荐的Penman-Monteith方法计算日ET0,采用Mann-Kendall检验法分析年、季度、月和年内日参照作物腾发量的变化趋势和突变情况,并进行其与主要气象因子的通径分析。结果表明:元谋地区ET0总体上均呈现逐渐下降的趋势。年参照作物腾发量1983年以后下降趋势明显;季度参照作物腾发量在1984、1994、1985和1990年分别出现一二三四季度的明显下降;多年平均月ET0在4月达到最大值,12月份达到最小值;年内日ET0在4或5月份出现峰值。对ET0影响为正的因子按大小排列为平均风速u2、最低气温Tmin、平均气温T、日照n和最高气温Tmax,对ET0的影响为负的因子影响大小顺序为平均湿度、水汽压、降雨和气压。

In order to explore trend of reference crop evapotranspiration（ ET0） and its main meteorological impact factors in Yuanmou dry- hot valleys during the last 57 years（ 1956- 2012）,we applied Penman- Monteith recommended by the United Nations Food and Agriculture Organization（ FAO） to calculate the evapotranspiration and analyze the trend and mutations of the reference crop evapotranspiration by Mann- Kendall method,and the main meteorological factors by path analysis of principle. Results showed that： ET0 generally decreased. The annual reference crop evapotranspiration was decreased evidently after 1983; seasonal reference crop evapotranspirations were decreased obviously in 1984,1994,1985 and 1990 respectively; the maximum average monthly ET0 appeared in April. The minimum ET0 appeared in December; the peak of daily ET0 appeared in April and May.The influences of positive factors to ET0 in the size were the average wind speed,minimum temperature,average temperature,number of sunshine hours,and the highest temperature. The influences of negative factors to ET0 in the size were the average humidity,vapor pressure,precipitation and the atmospheric pressure.