Principal Component And Multifractal Analysis On Reference Crop Evapotranspiration

Crop evapotranspiration is the basis to specify the irrigation water quota and implement scientific management of water resources. Crop evapotranspiration is also an important index to the measure of local water resources management, the change of the meteorological factors and the impact of the ecological environment. In recent years, with the impact of the climate environmental and the process of industrialization, the characteristics of reference crop evapotranspiration in each region is changing. accordingly. Based on the impact of climate changing on reference crop evapotranspiration, the multifractal analysis is employed to analysis the demand of water resource and the impact between the crop evaporation and the meteorological factors. We hope to provide a scientific reference in the impact of climate changing on the reference crop evapotranspiration, the tendency of reference crop evapotranspiration, the regional water resources planning and management as well as the ecological environmental renovation. This paper we take the reference crop evapotranspiration of the Linhe district of Inner Mongolia as the research object, the main content of this article and the related results are as follows:(1)Evaporation in this region is on the decline as a whole. The principal component analysis results on evaporation show that wind speed has a significant effect on the reference crop evapotranspiration of the region; the regression fitting result of extracting principal component which may not as good as the directly regression fitting, has more statistical significance.(2) Multifractal detrended fluctuation analysis and asymmetric multifractal detrended fluctuation analysis are introduced to analysis the reference crop evapotranspiration time series. The calculation results show that evaporation time series have multifractal characteristics, and summer evapotranspiration time series have stronger volatility and more obvious fractal features compared to other seasons; We analyze the time-varying feature of scaling asymmetries and then give the changing rule of the positive and negative trends of fluctuations. To a certain extent, enriched the content of evaporation fluctuations and provided a beneficial reference to fully understand it.(3) We utilized the multifractal detrended cross-correlation analysis method and the multifractal asymmetric cross-correlation analysis method to investigate the cross-correlation between the evapotranspiration and the meteorological factors. Results indicate that there is long-term memory in the cross-correlation between the evapotranspiration and the meteorological factors, and the main origin of these fluctuations may come from its own or from the related sequence for different meteorological factors at various scales; The asymmetric cross-correlation characteristics existing between the evapotranspiration and the meteorological factors depends on the meteorological factors, and the asymmetric cross-correlation between the evapotranspiration and the average temperature time series is the strongest while it is the weakest when it is related to the sunshine hours.