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The influence of the 1997–99 El Niňo Southern Oscillation on extratropical baroclinic life cycles over the eastern North Pacific
Author(s) -
Shapiro M. A.,
Wernli H.,
Bond N. A.,
Langland R.
Publication year - 2001
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49712757205
Subject(s) - extratropical cyclone , climatology , barotropic fluid , baroclinity , geology , storm track , meridional flow , zonal and meridional , atmospheric sciences , rossby wave , cyclogenesis , tropopause , potential vorticity , wind shear , cyclone (programming language) , environmental science , vorticity , storm , troposphere , wind speed , oceanography , meteorology , vortex , geography , computer science , computer hardware , field programmable gate array
The El Niňo Southern Oscillation (ENSO) strongly influences the interannual and seasonal atmospheric circulation over the North Pacific. The present study shows that the meridional displacement of the time‐mean upper‐level jet associated with ENSO modulates the time‐mean barotropic (meridional) wind shear over the central and eastern North Pacific storm track. Earlier theoretical and observational studies established the influence of barotropic wind shear on the life cycles of extratropical cyclones and their upper‐level potential vorticity (PV) waves. The present study suggests that differences in the time‐mean flow associated with the 1997–99 ENSO cycle had a similar impact on tropopause PV structure, meridional eddy fluxes of momentum and temperature, and predictability.