Objective Identification of the Tibetan Plateau Shear Line and Statistical Analysis of Its Spatiotemporal Evolution Features

This study aims to objectively and efficiently identify the TPSL (Tibetan Plateau shear line) and analyze the climatic characteristics of the TPSL. Based on comparison of the applicability of three high resolution reanalysis datasets (ERA-Interim, NCEP CFSR, and JRA-55) commonly used in the Tibetan Plateau area, the CFSR reanalysis dataset is selected as the basic dataset. According to the basic standard for manual identification of shear line and knowledge of computer geometry, an objective identification standard for TPSL is determined. The objectively identified TPSLs during 2005-2015 are compared with the TPSLs shown in the Tibetan Plateau Vortex and Shear Line Yearbook. On the basis of the comparison and verification, climatic characteristics of the TPSL in the recent 11 years are statistically analyzed. The annual average number of TPSLs is 49.4, among which 38 are eastern-type, which is also the basic type of TPSL. The maintenance time of the TPSL is 6 h usually. Areas of large total deformation, vertical vorticity, and horizontal divergence all are located between 94°-95°E. The objective TPSL identification method can efficiently identify the TPSL, and provides a new way to study the TPSL.