Influence of topography on the fine structures of stratospheric gravity waves: An analysis using COSMIC-2 temperature data

Abstract

We derive the potential energy of gravity waves (GWs) in the upper troposphere and stratosphere at 45°S–45°N from December 2019 to November 2022 by using temperature profiles retrieved from the Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) satellite. Owing to the dense sampling of COSMIC-2, in addition to the strong peaks of gravity wave potential energy (GWPE) above the Andes and Tibetan Plateau, we found weak peaks above the Rocky, Atlas, Caucasus, and Tianshan Mountains. The land–sea contrast is responsible for the longitudinal variations of the GWPE in the lower and upper stratosphere. At 40°N/S, the peaks were mainly above the topographic regions during the winter. At 20°N/S, the peaks were a slight distance away from the topographic regions and might be the combined effect of nontopographic GWs and mountain waves. Near the Equator, the peaks were mainly above the regions with the lowest sea level altitude and may have resulted from convection. Our results indicate that even above the local regions with lower sea level altitudes compared with the Andes and Tibetan Plateau, the GWPE also exhibits fine structures in geographic distributions. We found that dissipation layers above the tropopause jet provide the body force to generate secondary waves in the upper stratosphere, especially during the winter months of each hemisphere and at latitudes of greater than 20°N/S.

Keywords

• topography
• fine structures
• stratospheric gravity waves
• constellation observing system for meteorology
• ionosphere and climate-2 (cosmic-2)
• dissipation layers