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Abstract

The Tibetan Plateau (TP) exerts strong powerful thermal forcing, which plays a vital role in influencing weather–climate variations in Asia and even the Northern Hemisphere. However, the causes of thermal variation over the TP have not been fully revealed. Here, the role of winter soil moisture (SM) in subsequent summer thermal anomalies on the TP was investigated through multisource datasets for 1979–2014. Results indicate a significant positive relationship between winter SM and subsequent summer mean surface air temperature (SAT) was observed. Further investigations show that more (less) winter SM bring abundant (deficient) atmospheric water vapor in subsequent summer owing to its persistence. Furthermore, the Earth’s surface energy budget equation confirms that strengthened (weakened) surface downward longwave radiation caused by increased (decreased) water vapor-related winter SM is the dominant factor leading to SAT variations, even more significant for nocturnal SAT. The winter SM–atmospheric temperature positive relationship can extend from the surface to 200 hPa over the TP. Besides, the enhanced (weakened) atmospheric latent heat release associated with increased (decreased) water vapor content may be another important factor contributing to changes in atmospheric temperatures over the TP. Therefore, our results contribute to a better understanding of the effect of land–surface processes on thermal anomalies over the TP. With the decrease of snow depth over the TP in the past decades, the land-air interaction caused by SM during the freeze-thaw process may become more and more important.