Abstract
Using various observations and a chemistry-climate model, this study investigates the impact of wintertime total column ozone (TCO) on snow cover over the Tibetan Plateau (TP). The results indicate that during anomalously high TP TCO events, the snow cover on the TP is anomalously high, and vice versa. Further analysis reveals that high TP TCO leads to a warmer stratosphere and a colder troposphere. The stratospheric warming induces lower geopotential height in the upper troposphere and lower stratosphere (UTLS) over the TP. The cyclonic circulation in the UTLS associated with this low-pressure leads to high-potential vorticity (PV) stratospheric air being transported to the western TP. To maintain the conservation of PV, cyclonic vorticity forms above the western TP in the UTLS and can extend into the troposphere, then transporting water vapor from the Bay of Bengal and the Arabian Sea to the TP. The southerlies associated with this cyclonic circulation and positive vertical gradient of zonal wind in the troposphere induce ascending motions over the TP. Increased water vapor and ascending motions lead to more snowfall and cloud formation. The increased cloud enhances the cooling of the TP, leading to condensation process in the southern boundary of the TP and lower geopotential height in the UTLS over the TP. This decreased geopotential height strengthens the snowfall process. The increased snow cover in turn causes a cooling of the TP surface. This positive feedback further amplifies the snow cover variation. Model simulations suggest that a change of 10 DU in TCO can result in a 1.7% change in snow cover.
© 2025 American Meteorological Society. This is an Author Accepted Manuscript distributed under the terms of the default AMS reuse license. For information regarding reuse and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).
