Climate model biases in jet streams, blocking and storm tracks resulting from missing orographic drag

Pithan, F., Shepherd, T. G. ORCID: https://orcid.org/0000-0002-6631-9968, Zappa, G. and Sandu, I. (2016) Climate model biases in jet streams, blocking and storm tracks resulting from missing orographic drag. Geophysical Research Letters, 43 (13). pp. 7231-7240. ISSN 0094-8276 doi: 10.1002/2016GL069551

Abstract/Summary

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.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/66114
Item Type	Article
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	American Geophysical Union
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