Lightning in Western Patagonia
View/ Open
Date
2014Author
Garreaud, René D.
Nicora, M. Gabriela
Bürgesser, Rodrigo E.
Ávila, Eldo E.
Metadata
Show full item recordAbstract
On the basis of 8 years (2005-2012) of stroke data from the World Wide Lightning Location Network we describe the spatial distribution and temporal variability of lightning activity over Western Patagonia. This region extends from ~40°S to 55°S along the west coast of South America, is limited to the east by the austral Andes, and features a hyper-humid, maritime climate. Stroke density exhibits a sharp maximum along the coast of southern Chile. Although precipitation there is largely produced by cold nimbostratus, days with more than one stroke occur up to a third of the time somewhere along the coastal strip. Disperse strokes are also observed off southern Chile. In contrast, strokes are virtually nonexistent over the austral Andes -where precipitation is maximum- and farther east over the dry lowlands of Argentina. Atmospheric reanalysis and satellite imagery are used to characterize the synoptic environment of lightning-producing storms, exemplified by a case study and generalized by a compositing analysis. Lightning activity tends to occur when Western Patagonia is immersed in a pool of cold air behind a front that has reached the coast at ~40°S. Under these circumstances, midlevel cooling occurs before and is more prominent than near-surface cooling, leading to a weakly unstable postfrontal condition. Forced uplift of the strong westerlies impinging on the coastal mountains can trigger convection and produces significant lightning activity in this zone. Farther offshore, large-scale ascent near the cyclone's center may lift near-surface air parcels, fostering shallow convection and dispersing lightning activity.
xmlui.dri2xhtml.METS-1.0.item-citation
Garreaud, R. D., M. Gabriela Nicora, R. E., Bürgesser, and E. E. Ávila (2014), Lightning in Western Patagonia, J. Geophys. Res. Atmos., 119,
doi:10.1002/2013JD021160.