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Climate model biases in jet streams, blocking and storm tracks resulting from missing orographic drag
Author(s) -
Pithan Felix,
Shepherd Theodore G.,
Zappa Giuseppe,
Sandu Irina
Publication year - 2016
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 - 10.1002/2016gl069551
Subject(s) - orography , climatology , orographic lift , storm , climate model , jet stream , atmospheric circulation , environmental science , storm track , drag , coupled model intercomparison project , atmospheric sciences , middle latitudes , geology , climate change , jet (fluid) , meteorology , precipitation , geography , physics , oceanography , mechanics
State‐of‐the art climate models generally struggle to represent important features of the large‐scale circulation. Common model deficiencies include an equatorward bias in the location of the midlatitude westerlies and an overly zonal orientation of the North Atlantic storm track. Orography is known to strongly affect the atmospheric circulation and is notoriously difficult to represent in coarse‐resolution climate models. Yet how the representation of orography affects circulation biases in current climate models is not understood. Here we show that the effects of switching off the parameterization of drag from low‐level orographic blocking in one climate model resemble the biases of the Coupled Model Intercomparison Project Phase 5 ensemble: An overly zonal wintertime North Atlantic storm track and less European blocking events, and an equatorward shift in the Southern Hemispheric jet and increase in the Southern Annular Mode time scale. This suggests that typical circulation biases in coarse‐resolution climate models may be alleviated by improved parameterizations of low‐level drag.