Effects Of East China Sea SST On Soil Moisture In Eastern China

Studies have shown that both the ocean and the land have a“memory”effect on climate,and both sea surface temperature and soil moisture are important climate driving factors.Therefore,studying the evolution characteristics of sea surface temperature and soil moisture and their possible connection is of great significance for climate prediction,weather forecasting,and hydrological cycle.This article uses reanalysis data to focus on the temporal and spatial distribution characteristics of sea surface temperature and soil moisture,and tries to find the connection between these two elements.Based on HadISST data,the characteristics of the sea surface temperature evolution of the East China Sea were analyzed.From 1969 to 2018,the sea surface temperature in the East China Sea shows a significant upward trend.Through the 99%Mann-Kendall trend test,the sea surface temperature in the four seasons also shows a significant upward trend,among which the winter sea surface temperature is the most obvious.In the past 50 years,the mean sea surface temperature field in the East China Sea is between 13?and 26?,and the isotherm shows a“Southwest northeast”trend.The horizontal gradient of the isotherm near the land is larger than that in the open sea.In the past 50 years,the soil moisture in Eastern China showed a significant downward trend.The average soil moisture field in Eastern China ranges from 8 kg/m~2 to 40kg/m~2,showing the overall distribution pattern of wet in the south and dry in the north.Among them,the area with the highest soil moisture is Jiangnan,and the area with the lowest soil moisture is North China.Using GLDAS data to investigate the temporal and spatial distribution characteristics of precipitation,evaporation and water surplus and loss in eastern China,it can be seen that the three factors have shown an upward trend in the past 50 years,and the upward trend of precipitation and evaporation is significant.Using regional correlation analysis to analyze the correlation between these three factors and soil moisture and sea surface temperature,the results showed that the sea surface temperature,soil moisture and precipitation and water surplus and loss showed significant positive correlation in the area south of the Huai River.Correlation analysis,causality analysis and synthesis analysis were used to analyze the response relationship between soil moisture in Eastern China and sea surface temperature in the East China Sea.It can be seen that the influence of sea surface temperature in the East China Sea on the soil moisture in Eastern China is concentrated in the area south of the Huai River,showing a significant positive correlation.The result of causality analysis shows that the influence of sea surface temperature on soil moisture is greater than that of soil moisture on sea surface temperature.In addition,when the sea surface temperature in the East China Sea is abnormally high,positive anomalies usually occur in southern China and eastern North China.Combining with the results of anomalous precipitation synthesis,it is believed that the possible mechanism of the influence of sea surface temperature on soil moisture is:when the sea surface temperature of the East China Sea is abnormally high,it will affect the abnormal atmospheric circulation,and a large amount of water vapor will be transported to the area south of the Huai River,resulting in abnormal precipitation in this area more,leading to an increase in surface soil moisture.