Gravity wave activities in Tibet observed by COSMIC GPS radio occultation

Abstract

The Gravity waves activities in the Tibetan Plateau are very complex with different effects and natures that are not clear due to the lack of high resolution data from space and also from ground. In this paper, using COSMICGPS radio occultation data from 2006 to 2014, the atmospheric gravity waves activities and climatologic behaviors in Tibetan stratosphere are studied and analyzed, which show different characteristics. Most of the gravity waves with potential energy (Ep) at altitude of 17–24 km are associated with mountain waves. A good correlation between gravity wave activities and zonal wind flow is found. The distribution of gravity wave (GW) activities in Tibet is strongly connected with zonal wind variation and topography. GW activities are enhanced in winter seasons and decreased in summer seasons since strong western winds persist at all heights of the Tibetan troposphere. The gravity waves generated in the Tibetan area are mostly related to the orography of the area. The vertical wavelengths of GWS are shorter. Gravity waves in the Northwest have different vertical wavelengths in the Southeastern part of Tibetan Plateau, and dominant wavelengths are 3–5 km in the Northwest and 2–3 km in the Southeast, respectively. In the summer, the Northwestern part is the main source of wave generation while in the winter the GW is generated almost from all peaks of the Tibetan Plateau. Gravity waves in the region are clearly related to deep convection, which can also be proved by the inverse relation of Outgoing long wave radiation (OLR) and potential energy (Ep). Keywords: Gravity waves, Mountain wave, COSMIC GPS radio occultation, Tibet