The Persistence and Reemergence of Atmospheric Anomaly Signals in Soil Temperature

Abstract

AbstractThe anomalies of soil temperature (ST) in shallow soil are potential signals for both weather forecast and climate prediction. Results show atmospheric anomaly signals can persist from zero to several months in the form of ST anomalies in shallow soil, and the persistence of ST anomalies caused by atmospheric anomalies in different months is significantly different. ST anomalies in shallow soil caused by air temperature can persist for longer time than those caused by precipitation. The decrease in instantaneous precipitation and air temperature leads to the weakening of atmosphere interference with ST anomaly persistence, which enhances the persistence of ST anomalies caused by initial air temperature anomalies. Moreover, the reemergence of ST anomalies in shallow soil from air temperature is a more common phenomenon than one from precipitation. ST anomaly reemergence may be caused by two processes. Freeze‐thaw process is one of the processes, and it has been confirmed in both observations and simulations. Another may be related to the changes of the vertical distributions of hydraulic and thermal conductivities due to the changes in air temperature and precipitation when the climate shifts from warm‐wet to cold‐dry. However, the reemergence of ST anomalies only occurs in the simulations where freeze‐thaw processes exist using the Community Land Model 4.5 (CLM4.5). The persistence and reemergence of observed ST anomalies are not fully captured in numerical simulations using CLM4.5, which requires further research to improve the simulation performance of numerical models.