气象因子在海河流域蒸发悖论中的作用机理

蒸发是水文循环的重要环节。利用Mann-Kendall趋势检验方法检测了海河流域1961-2006年蒸发皿蒸发量的演变趋势。结果表明:海河流域蒸发皿蒸发量呈现出显著的下降趋势。利用相关分析、偏相关分析和主成分分析方法,研究了蒸发皿蒸发量与平均气温、相对湿度、平均风速和日照时数4种气象因子之间的关系。基于这4种气象因子,建立了模拟蒸发皿蒸发量的经验公式(E-THWS公式),并利用这一公式的微分形式揭示了这4种气象因子在海河流域"蒸发悖论"中的作用。结果表明:平均气温和相对湿度对海河流域蒸发皿蒸发量的增加作用要小于平均风速和日照时数的减少作用;平均风速的下降是蒸发皿蒸发量下降的主要原因。

Mechanism of effect of meteorological factors in paradox theory of pan evaporation of Haihe River basin

Evaporation is an important part of hydrological circulation. The Mann-Kendall's trend test technique was used to detect the trend of pan evaporation in the Haihe River basin (HRB) from 1961 to 2006. The results showed that there is a statistically significant decreasing trend of pan evaporation in the HRB. Correlation analysis, partial correlation analysis, and principal component analysis were used to analyze the relationship between pan evaporation and four meteorological factors such as mean temperature, relative humidity, wind speed and sunshine duration. The paper set up an empirical formula (E-THWS formula) for calculating pan evaporation based on the four meteorological factors, and announced the effect of four meteorological factors in paradox theory of pan evaporation of Haihe River basin . The results indicated that the increasing effect of pan evaporation by mean temperature and relative humidity is less than the decreasing effect of pan evaporation by average wind speed and sunshine duration.The decrease of average wind speed is the chief reason resulting in the decrease of pan evaporation in HRB.