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Journal Article: BibTeX citation key:  Froehlich2012a
Froehlich, L., Knippertz, P., Fink, A. H. & Hohberger, E. (2012) An objective climatology of tropical plumes. IN Journal of Climate, 24. 5044–5060.
Added by: Andreas Fink 2013-05-16 15:14:40    Last Edited by: Andreas Fink 2013-07-01 11:31:16
 B  
Categories: Atmospheric processes
Keywords: Clouds - Convection, Dynamics, Interannual variability, Radiation, Satellites
Creators: Fink, Froehlich, Hohberger, Knippertz
Collection: Journal of Climate

Peer reviewed
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Popularity index:  44.92%

 
Abstract
The first global objective climatology of Tropical Plumes (TPs), obtained from a novel
algorithm based on gridded 10.8-μm brightness temperatures (Tb), is presented for
1983-2006. TPs are defined as continuous cloud bands (>2000 km) crossing 15°N or
15°S with Tb anomalies of less than -20 K and a lifetime of at least 3 hours. A
minimum length-to-width ratio of three filters for elongated features. Numbers of
identified TPs are sensitive to the chosen thresholds, but not their geographical
distribution and seasonal cycle.
TPs are an important indicator of tropical-extratropical interactions with impacts on
radiation and moisture. TP occurrence during boreal winter is largely confined to
oceanic regions with main maxima over the South Pacific and South Atlantic as well as
the eastern North Atlantic and Pacific Oceans. The geographical distribution during
boreal summer is similar, but with lower frequencies, except for monsoon-influenced
regions. Interannual variations over the Indo-Pacific region are strongly related to El
Niño. TPs often develop downstream of extratropical upper-level troughs propagating
into low latitudes, particularly over the wintertime eastern North Pacific and North
Atlantic, but also in regions where mean upper-level easterlies do not generally favor
equatorward Rossby wave propagation. Synoptic-scale variations in the quasipermanent
cloud bands associated with the South Pacific and South Atlantic
Convergence Zones frequently produce TP-like anomalies, which are climatologically
associated with downstream upper-level troughs. Some regions also feature TPs
associated with mesoscale tropical disturbances. The new TP algorithm will serve as a
basis for more-in-depth studies in the future.
Added by: Andreas Fink    Last Edited by: Andreas Fink