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contributor authorThompson, David W. J.
contributor authorLi, Ying
date accessioned2017-06-09T16:57:34Z
date available2017-06-09T16:57:34Z
date copyright2015/03/01
date issued2014
identifier issn0022-4928
identifier otherams-77075.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4219593
description abstractarge-scale variability in the Northern Hemisphere (NH) circulation can be viewed in the context of three primary types of structures: 1) teleconnection patterns, 2) a barotropic annular mode, and 3) a baroclinic annular mode. The barotropic annular mode corresponds to the northern annular mode (NAM) and has been examined extensively in previous research. Here the authors examine the spatial structure and time-dependent behavior of the NH baroclinic annular mode (NBAM).The NAM and NBAM have very different signatures in large-scale NH climate variability. The NAM emerges as the leading principal component (PC) time series of the zonal-mean kinetic energy. It dominates the variance in the wave fluxes of momentum, projects weakly onto the eddy kinetic energy and wave fluxes of heat, and can be modeled as Gaussian red noise with a time scale of ~10 days. In contrast, the NBAM emerges as the leading PC time series of the eddy kinetic energy. It is most clearly identified when the planetary-scale waves are filtered from the data, dominates the variance in the synoptic-scale eddy kinetic energy and wave fluxes of heat, and has a relatively weak signature in the zonal-mean kinetic energy and the wave fluxes of momentum. The NBAM is marked by weak but significant enhanced spectral power on time scales of ~20?25 days.The NBAM is remarkably similar to its Southern Hemisphere counterpart despite the pronounced interhemispheric differences in orography and land?sea contrasts.
publisherAmerican Meteorological Society
titleBaroclinic and Barotropic Annular Variability in the Northern Hemisphere
typeJournal Paper
journal volume72
journal issue3
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/JAS-D-14-0104.1
journal fristpage1117
journal lastpage1136
treeJournal of the Atmospheric Sciences:;2014:;Volume( 072 ):;issue: 003
contenttypeFulltext


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