Application of Principal Component Analysis in Evaluating Influence Factors of Evaporation in Northern Cold Area

There are many meteorological factors affecting evaporation, which are not only considered comprehensively, but also their influence degree respectively. The contribution of each factor to principle component can be reflected by the coefficient of each factor in principal component equation, and then the main factor can be determined. Taking Chahayang irrigation area in Heilongjiang province for example, the data of influence factors from May to September in 2007 such as temperature, relative humidity, wind speed, vapor pressure and sunshine is analyzed with principal component analysis (PCA for short). The results show that the change of evaporation is the result of the combined effect of numerous metrological factors which interact with each other, but when the temperature is kept unchanged, the average sunshine turns out to be the main factor.