Open AccessAtmospheric blocking in a high resolution climate model: influences of mean state, orography and eddy forcing
Author(s) -
Berckmans Julie,
Woollings Tim,
Demory MarieEstelle,
Vidale PierLuigi,
Roberts Malcolm
Publication year - 2013
Publication title -
atmospheric science letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.951
H-Index - 45
ISSN - 1530-261X
DOI - 10.1002/asl2.412
Subject(s) - orography , climatology , forcing (mathematics) , geopotential height , blocking (statistics) , environmental science , northern hemisphere , atmospheric sciences , jet stream , atmospheric circulation , climate model , atmospheric model , climate change , meteorology , geology , jet (fluid) , precipitation , geography , physics , statistics , oceanography , mathematics , thermodynamics
An underestimate of atmospheric blocking occurrence is a well‐known limitation of many climate models. This article presents an analysis of Northern Hemisphere winter blocking in an atmospheric model with increased horizontal resolution. European blocking frequency increases with model resolution, and this results from an improvement in the atmospheric patterns of variability as well as a simple improvement in the mean state. There is some evidence that the transient eddy momentum forcing of European blocks is increased at high resolution, which could account for this. However, it is also shown that the increase in resolution of the orography is needed to realise the improvement in blocking, consistent with the increase in height of the Rocky Mountains acting to increase the tilt of the Atlantic jet stream and giving higher mean geopotential heights over northern Europe. Blocking frequencies in the Pacific sector are also increased with atmospheric resolution, but in this case the improvement in orography actually leads to a decrease in blocking Copyright © 2012 Royal Meteorological Society and British Crown copyright, Met Office .