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Subtropical Westerly Jet Influence on Occurrence of Western Disturbances and Tibetan Plateau Vortices
Author(s) -
Hunt K. M. R.,
Curio J.,
Turner A. G.,
Schiemann R.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl077734
Subject(s) - plateau (mathematics) , climatology , orography , jet stream , subtropics , westerlies , polar vortex , troposphere , geology , vortex , baroclinity , atmospheric sciences , precipitation , jet (fluid) , geography , meteorology , physics , mathematical analysis , mathematics , fishery , biology , thermodynamics
Abstract Western disturbances (WDs) are midtropospheric to upper‐tropospheric mesoscale vortices, which typically propagate along the subtropical westerly jet stream and bring heavy rainfall to Pakistan and northern India during boreal winter. They are dynamically similar to Tibetan Plateau vortices (TPVs), which affect southwest China during spring and summer and emanate from the Tibetan Plateau. Here we propose that their similarity implies the existence of a more general group of upper‐tropospheric vortices featuring interactions with the orography of the Hindu Kush‐Himalaya‐Tibetan Plateau region. Using existing track databases for WDs and TPVs derived from ERA‐Interim reanalysis, we show that their respective occurrence frequencies are highly anticorrelated with each other through the seasonal cycle, yet both are strongly correlated with jet latitude. Our findings imply that the incidence of hazards due to WDs and TPVs is correlated on intra‐annual and interannual time scales, particularly through upper‐level baroclinicity.