论文部分内容阅读
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（ＥＴｐ）。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。
Based on the multi-year series observation data of Beijing Changping weather station and the formula recommended by the World Food Program (FAO), the average ETp of the 10-day period of each month was calculated. Through the analysis shows that the potential evapotranspiration showed a seasonal trend. The mean and standard deviation (STD) of potential evapotranspiration can all be well approximated by the second-order components of the Fourier series. The potential evapotranspiration is a random variable whose random variation follows a normal distribution and the mean and standard deviation of the distribution vary with the seasons.