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contributor authorColucci, Stephen J.
date accessioned2017-06-09T14:36:48Z
date available2017-06-09T14:36:48Z
date copyright2001/04/01
date issued2001
identifier issn0022-4928
identifier otherams-22816.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4159308
description abstractThe local preconditioning of the midtropospheric planetary-scale flow prior to the onset of a blocking episode during January 1985 is investigated. The preconditioned flow is anomalously diffluent, or characterized by anomalously negative planetary-scale, geostrophic stretching deformation. This deformation increases in magnitude with time during the transition to blocking; this tendency in turn is quasigeostrophically forced by the shape of the planetary-scale component of potential vorticity transports. In particular, the planetary-scale component of potential vorticity advection that became increasingly anticyclonic with eastward distance at a rate that increased northward near the block-onset region forced the local planetary-scale flow to become more diffluent prior to blocking. Self-interactions among the synoptic-scale waves and synoptic-to-planetary-scale interactions contributed more importantly than self-interactions among planetary-scale waves to this preconditioning. In the frequency domain, the preconditioning is primarily attributable to the interactions between low- and high-frequency components of the flow, notably to the advection of slowly varying, low potential vorticity by the high-frequency flow.
publisherAmerican Meteorological Society
titlePlanetary-Scale Preconditioning for the Onset of Blocking
typeJournal Paper
journal volume58
journal issue8
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/1520-0469(2001)058<0933:PSPFTO>2.0.CO;2
journal fristpage933
journal lastpage942
treeJournal of the Atmospheric Sciences:;2001:;Volume( 058 ):;issue: 008
contenttypeFulltext


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