Research On Spatial And Temporal Distribution Of Reference Crop Evapotranspiration And Surface Humidity Index In Chongqing

Earth is an opened Large-System, so that the changing of every element could cause a heavy influence on it. With the increasing of the earth surface temperature, which was affected by the evolution of earth system and human activities, hydrological cycle on earth was been highly affected for the spatial and temporal distribution of meteorological elements, like precipitation, and water resources changing in Chongqing.Chongqing, located in the east of Sichuan Basin, Southwest China, is been embraced by big mountains. The regional climate that created by the special location and geomorphologic conditions, has its own inconformity compared with other parts of China. Therefore, it is of great theoretical and practical significance to implement the changing characteristics and reasons of reference crop evapotranspiration and surface humidity index in Chongqing.This study is based on the meteorological data, such as daily temperature, precipitation, sunshine duration, air relative humidity, wind speed, and atmosphere pressure, measured daily at 34 stations from 1960 to 2008 in Chongqing Municipality of China, and achievements summarized based on domestic and foreign relative research. Main contents are as follows:First, explored the characteristics of the climate in Chongqing by the spatial and temporal distributes analysis of five main meteorological factors; Then, analyzed the spatial and temporal distribution and changing trend of reference crop evapotranspiration and humidity index that calculated by using Penman-Monteith model, by using the linear regression, Inverse Distance Weighted (IDW) methods on Arc GIS 10.0, Mann-Kendall mutation test, Morlet wavelet analysis, et al; In the End, Found out the main climatic affected factors of reference crop evapotranspiration and humidity index, by using relevance relation among reference crop Evapotranspiration, humidity index and climatic factors. Conclusions have been drawn as follows:(1) The trends of temperature and air relative humidity in most places of Chongqing from 1960 to 2008 were increased, whereas the trends of precipitation, wind speed and sunshine duration were decreased. Spatially, the means temperature exhibited higher in Midwest, and higher in northeast and southeast Chongqing. The precipitation showed a gradual increase from the west to the southeast and northeast, wind speed was higher in the northwest and mid-north of Chongqing, sunshine duration was higher in the northeast and lower in the southwest, and air relative humidity appeared as a gradual decrease from the northwest to the southeast and the northeast.(2) The trend of annual reference crop evapotranspiration in Chongqing showed a distribution as a gradual decrease from the northeast and southeast to the west spatially. Temporally, most places of Chongqing showed a decreased trend, and the abrupt year is 1967 by Mann-Kendall abrupt changes inspection method. The departure sequence vibration of annual reference crop evapotranspiration in Chongqing is quasi 3,9, and 14 years by wavelet analysis. The situations were different in four seasons. By contrast with the period from 1960 to 1980, the annual and seasonal reference crop evapotranspiration in Chongqing from 1981 to 2008 were all decreased, and the places that decreased heavily were mainly concentrated in north of line " Yun Yang-Wan Zhou ", and around the line " Chang Shou-Wu Long-Qian Jiang "(3) The mean surface humidity index in Chongqing from 1960 to 2008 is 1.82. Spatially, the surface humidity index appears lower in the river valleys, like Changjiang, Jialingjiang, and Qijiang, and higher in the southeast, Chengkou, Dianjiang, and Yubei. Temporally, the surface humidity index in most places of Chongqing showed a not significant rising, and the abrupt year is 1979. The departure sequence vibration of annual surface humidity index in Chongqing is quasi 3,5,8-9, and 15 years by wavelet analysis. The situations were different in four seasons.(4) The mainly affected meteorological factors of the annual and seasonal reference crop evapotranspiration decreasing in Chongqing from 1960 to 2008 are all air relative humidity, sunshine duration and wind speed. The main reasons of the decrease of it were the rising of air relative humidity and the decreasing of wind speed and sunshine duration. The mainly affected meteorological factors of the annual and seasonal reference crop evapotranspiration in Chongqing from 1960 to 2008 are all reference crop evapotranspiration, precipitation, and air relative humidity. The main reasons of the change of it in annual, spring, summer, and winter were the rising of precipitation and air relative humidity, and the increase of reference crop Evapotranspiration, while in autumn were the decrease of precipitation and the increase of highest and mean temperature.