Mechanism of Atmospheric Diabatic Heating Effect on the Intensity of Zonal Shear Line Over the Tibetan Plateau in Boreal Summer

Abstract

AbstractThe zonal shear line (ZSL) over the Tibetan Plateau (TP) is one of the most crucial synoptic systems inducing precipitation over the TP in boreal summer. However, few studies have comprehensively explored the thermal mechanism of the intensity evolution of the ZSL. In this study, the mechanism of the atmospheric diabatic heating (hereafter referred to as diabatic heating) effect on the intensity of the ZSL was explored by the methods of composite and diagnostic analysis. Based on the fifth generation European Centre for Medium‐Range Weather Forecasts atmospheric reanalysis of the global climate hourly data sets from June to August during 1980–2019, 11 cases of the ZSL were selected by using the objective identification method. Results suggest that a close relationship exists between the ZSL’s intensity and the 10‐h‐earlier vertically integrated diabatic heating <Q1>, with a high correlation coefficient of 0.81. The intensity of <Q1> peaks at around 13 LST (Local Solar Time) within a day. The diabatic heating rate Q reaches the maximum values at 350 hPa. The vertical transport of temperature is the main contributor to the intensity of Q during the intensity evolution of the ZSL. The vertically non‐uniform diabatic heating effect is the primary mechanism for the intensity evolution of the ZSL. When the vertically non‐uniform diabatic heating near the ZSL enhances (weakens), it will be favorable (unfavorable) to enhance the ZSL’s intensity.