Spatiotemporal Variations Of Soil Moisture And It’s Influencing Factor Analysis In The Tarim River Basin

The high-resolution ECV soil moistue data, which was developed by the European Space Agency. was used to anaysis the spatial and temporal changes of soil moisture in the Tarim Basin, then, anaylze the meteorological factors and the the large-scale circulation features, which has the impact to the soil mositure. So that, the paper can provide the decision support for the sustainable development in the Tarim River basin.Firstly, use the observation data, runoff data and the ERA-Interim/Land to prove the ECV soil moisture data has a good applicability in the Tarim Basin. Then, on the basis of empirical orthogonal function by (EOF), the correlation coefficient analysis, singular value decomposition (SVD) and other methods to study thespatial and temporal changes of soil moisture in the Tarim Basin and the meteorological factors and the large-scale circulation features for the soil moisture. The main conclusions are as follows:1, the ECV soil moisture data was compared respectively with the observation data in Shache station, the runoff data in the Alar hydro logical station and the ERA-Interim/Land Soil moisture data. The result shows that the ECV soil moisture has a same changes in time series compared with the observation data, runoff data and the ERA-Interim/Land soil moisture data. However, the spatial distribution of the soil moisture has a big different in the Tarim River basin between the ECV soil moisture data and the ERA-Interim/Land data. The ERA-Interim/Land soil moisture have not change in seasons, while the ECV soil moisture can reflect the soil moisture changes in seasons and spatial distribution in the Tarim River basin. ECV soil moisture data can more accurately reflect the trends and spatial distribution of soil moisture in the Tarim Basin.2, the soil moisture(March-November) keeps a wet state in the Tarim River basin from the late 1980s to the mid-1990s, and afer the mid-1990s, the soil moishtre turns to a dry state in the Tarim River basin, the region between the Yarkand River and Hotan River is the most obvious change area. In spring, the soil moisture in the Tarim River basin keeps dry trend before the mid-1990s, and then turn to the wet trend, the most obvious change area was located in the central of the basin. The change trend of the soil moisture in the Tarim River basin was not significant in the summer and the autumn, while the soil moisture in the whole basin are declining.3, The soil moisture in the Tarim River basin have a significant negative correlation with the temperature, and have a positive correlation with the precipitation The correlation with the precipitation is better than teh correlation withe the temperature. There are response between the soil moisture and the metrological, the soil moisture in every month has negeative correlation withe the temperatue, and the most negotive corelation is between the soil moisture and the temperature when the same time. The correlation is more complex between the soil moisutre and the precititation in every month, but all the precipitation in the same month there was a significant positive correlation.4, The SVD result between the soil moisture and the 850hPa geopotential height field shows that the soil moisthre in the Tarim river basin has a positive correlation in the north-central Eurasia 850hPa geopotential height, The soil moisture in western region has positive correlation with the Atlantic SST and has a negative correlation with the equatorial eastern Pacific region. and the eaestern region has negative correlation with the Atlantic SST and has positive correlation with the equatorial eastern Pacific region. Correlated the soil moisture and the cirluation index which was selected by this resherach, and found that the correlation between the soil moisure in the Tarim River basin and the herein cirlulation index is better than the season scale correlation. The majority of the circulation index have positive correlaiton with the soil moisure when lag 0-1 month, and have negative correlation when lag 2-6 month, and in four, five months time lag, the correlation ia most obvious.