潜在腾发量的季节性变化趋势及概率分布特性研究

Seasonal Variation Trend and Probability Distribution Pattern of Potential Evapotranspiration

摘要: 利用北京昌平气象站多年系列观测资料和世界粮农组织(FAO)建议的公式计算了历年各月逐旬潜在腾发量的平均值(ET_p).通过分析表明,潜在腾发量呈明显的季节性变化趋势。潜在腾发量的多年均值和标准差(STD)都能用Fourier级数的二阶分量来作很好的近似。潜在腾发量是一个随机变量,其随机变化规律服从正态分布,该分布的均值和标准差都随着季节而变化。

Abstract: Based on the serial meteorological data from Changpin Meteo rological Stations located in the suburb of Beijing the every ten-day period average potential evapot ranspiration(ET_p)were calculated and analyzed.The analysis shows that the ET_p changes in a strong seasonal trend of which the mean and STD fit to the two-harmonics of Fourier series approximately.Moreover,ET_p is a random variable which follows the normal distribution with mean and deviation changing with season.Finally,the probability density function of ET_p is given.