Contribution of sea surface temperature anomalies in the Barents and Yellow-Japan Seas to summer high temperature anomalies over the eastern Tibetan Plateau

Abstract

In the summer of 2022, extremely high surface air temperature (SAT) anomalies occurred over the Tibetan Plateau (TP), especially the eastern TP (ETP). Using the 2022 high SAT anomaly over the ETP as an example, the present study investigates the characteristics of the variability of summer SATs over the ETP and associated oceanic forcing factors. The results reveal that the warmer sea surface temperature anomalies (SSTAs) in the Barents Sea (BS) and Yellow-Japan Sea (YJS) are jointly responsible for the higher summer SATs over the ETP for the period 1961–2022 and can also explain the higher ETP SAT anomaly in the summer of 2022. The warmer BS SSTA can lead to an upper-tropospheric high-pressure anomaly around the ETP (i.e., a strengthened and northeastward-extended South Asian high) and the associated higher ETP SAT anomaly by exciting local upper-tropospheric geopotential height anomaly over the BS and accordingly modulating the downstream Rossby wave from the BS to the ETP. The warmer YJS SSTA can directly cause an upper-tropospheric high-pressure anomaly around the ETP and YJS and eventually enhance the SATs over the ETP through stimulating local upward motion and guiding the Rossby wave from the upstream region to the ETP and YJS. This mechanism can also explain the extremely high SAT anomaly over the ETP in the summer of 2022. Moreover, the BS and YJS SSTAs can effectively modulate the summer SATs over the ETP even though the absence of the effect of El Niño/La Niña. These findings may provide valuable insights into the reason for the variability of summer SATs over the TP.