[Seminar on Nov 15] Climatology of Tibetan Plateau Vortices in Reanalysis Data and a High-resolution Global Climate Model
National Centre for Atmospheric Science,
University of Reading, UK
Room 1118, New Building, IAP
9am, Nov 15, 2018
The Tibetan Plateau (TP) and surrounding high mountain ranges constitute an important forcing of the atmospheric circulation over Asia due to their height and extent, and thereby impact weather and climate in downstream regions of East Asia. Mesoscale Tibetan Plateau vortices (TPVs) are one of the major precipitation-producing systems on the TP. A fraction of TPVs move off the TP to the east and can trigger extreme precipitation in parts of China, that can result in severe flooding. In this study, the climatology of TPV occurrence is examined in two reanalyses and, for the first time, in a high-resolution global climate model using an objective feature-tracking algorithm. Most TPVs are generated in the north-western part of the TP; the centre of this main genesis region is small and stable throughout the year. The strength and position of the subtropical westerly jet seems to control the distance TPVs can travel eastwards. Additionally, we hypothesize that the jet might have an impact on the annual cycle and the interannual variability of TPV occurrence frequency but the dynamical mechanism is unclear and will be subject of a future study. The results show that the global climate model is able to simulate TPVs at N512 (~25 km) horizontal resolution and in general agrees with the reanalyses.