Soil Moisture Memory and Its Effect on the Surface Water and Heat Fluxes on Seasonal and Interannual Time Scales

Abstract The persistence of soil moisture anomalies has an important effect on the weather and climate forecasts. Numerous observational and modeling studies have addressed the memory of soil moisture anomalies and its effects at the seasonal scale, and few studies have focused on the interannual scale. This study investigates the soil moisture memory and its effect on the surface heat and water fluxes under different atmospheric conditions on seasonal and interannual scales using the Community Land Model Version 4.5 driven by the observations at the Tongyu site. The results indicate that the soil moisture anomalies can persist for more than 1 year. It was found that the decay rate of soil moisture anomalies depends mainly on initial soil moisture anomalies, followed by atmospheric condition in this study. Under the same atmospheric condition, the wet anomalies of soil moisture decay faster than dry anomalies of soil moisture. With the same initial soil moisture anomalies, soil moisture memory is usually shorter under the wet atmospheric condition. Moreover, the soil moisture anomalies have an obvious exponential decrease over the years. The anomalies of the surface heat fluxes have significant interannual attenuation trend and seasonal variations, and they are closely related to the anomalies of surface temperature, which are mainly affected by the anomalies of soil specific heat capacity. This study provides a scientific support for understanding the persistence of soil moisture anomalies, and it may be useful for the research on the seasonal and interannual variability of climate.