Distribution characteristics of skin temperature over Tibetan plateau in summer

Abstract

As the "roof of the world", the Tibetan Plateau (TP, in short) exhibits the distinctive "heat island" characteristics compared to the same latitude region, and plays a decisive role in the atmospheric thermal structure of the TP and surroundings. ERA5 reanalysis data from January 2017 to December 2020 are used to analyze the meridional distribution characteristics of the average skin temperature and the potential temperature lapse rate at coldest point tropopause (CPT) in the highaltitude areas of the TP in summer. The Pearson correlation coefficient between the measured data and the reanalyzed data in the Da Qaidam area (95°21’E, 37° 51’N, 3180m above sea level (ASL)) in August 2020 is 0.88, indicating good usability of the reanalyzed data. The average skin temperature of TP in summer shows a feature of "high in the south and low in the north", which is ~20° higher than the atmospheric temperature of surrounding low-altitude area at the same altitude. The distribution of heat sources on the TP not only affects the location and intensity of the South Asian High, but also aggravates the thermal difference between land and sea, which promotes the formation of the Asian summer monsoon. The strong heat source in the southern TP, on the one hand, directly affects the atmospheric thermal structure over the southern TP through enhancing upward transportation; on the other hand, indirectly affects the high-altitude atmospheric thermal structure of the region north to TP through the background transportation of westerly and summer monsoons. The potential temperature lapse rate at CPT over the high-altitude area of TP also has significant characteristics of north-south differences, indicating that the "heat source effect" can regulate the intensity of atmospheric turbulence.