Temperature, water vapor and tropopause characteristics over the Tibetan Plateau in summer based on the COSMIC, ERA-5 and IGRA datasets

Abstract

We established a set of atmospheric standard temperature and water vapor profiles and examined the characteristics of the tropopause over the Tibetan Plateau in summer using IGRA, COSMIC and ERA-5 datasets. We studied the temperature and water vapor profiles under clear sky, cloudy and “other” conditions and their diurnal variation. The atmosphere over the Central Tibetan Plateau is warmest and wettest in the lower to mid-troposphere, whereas the Western Tibetan Plateau is warmest and driest in the mid to high troposphere. The coldest and wettest air near the tropopause is over the Eastern Tibetan Plateau. The height of the tropopause decreases gradually from west to east over the plateau, although the difference in height is ≤0.5 km. Relative to clear sky conditions, cloudy conditions are characterized by warming and wetting anomalies in the lower to mid-troposphere and cooling and wetting anomalies in the tropopause and lower stratosphere. The largest vertical diurnal differences in temperature are at the surface and the difference decreases with increasing altitude from the surface to ~12 km. The difference between the six time periods of early morning, morning, noon, afternoon, evening and midnight are within −0.5 to 0.5 K above 12 km. The difference in water vapor between the six time periods is ≤0.2 g m−3. The lowest tropopause is at early morning. The height of the tropopause then increases followed by a decrease, with a sharp peak at noon. This establishment of a set of atmospheric standard profiles over Tibetan Plateau provides more accurate inputs for climate models.