An empirical genesis index of Tibetan Plateau vortex and its relationship with environmental factors

Tibetan Plateau (TP) is named “the Asian water tower” since it provides fresh water for hundreds of millions of people in Asia. Tibetan Plateau vortices (TPVs) are the major precipitation-producing system over TP, and thus are of importance to the water cycle and the severe disasters of TP and the downstream regions. Using the Poisson regression, an empirical genesis index of TPVs G_TPV is constructed based on a long-term database of TPVs derived from the reanalysis datasets. The spatiotemporal characteristics of TPVs are well reproduced by G_TPV. Relative contribution of environmental factors shows that, the environmental factors reflected the sensible heat (elevation and the ground-air temperature difference) play a crucial role in the spatial distribution of TPVs, and the environmental factors represented the latent heat (the difference between upper-level and lower-level divergence, relative vorticity at 500 hPa, and the mid-tropospheric humidity) determine the interannual variations of TPVs. In the annual cycle of TPVs, both the latent heat and the sensible heat are of importance. The genesis climatology of TPVs from the Yearbook by manual tracing and G_TPV via other reanalysis datasets are also used to evaluate the performance of the genesis index. It implies the potential capability of G_TPV to understand the mechanism of the genesis and development of TPVs, and to analyze the TPVs from the GCMs with the coarse resolutions.