Universität zu Köln

Reyers, Mark ORCID: 0000-0001-7085-9345 and Shao, Yaping ORCID: 0000-0002-2041-5479 (2019). Cutoff lows off the coast of the Atacama Desert under present day conditions and in the Last Glacial Maximum. Glob. Planet. Change, 181. AMSTERDAM: ELSEVIER. ISSN 1872-6364

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Abstract

Cutoff lows (COLs) over the subtropical Southeast Pacific may have a distinct impact on the local climate in Northern Chile and in the Atacama Desert. They are associated with generally wetter conditions and also influence the thermally driven wind regimes. In this study, mid-tropospheric COLs in the specific region off the coast of the Atacama Desert north of 30 degrees S are analysed for austral winter (April September). For the recent past climate slightly more than four COLs per winter on average are detected in ERA-Interim reanalysis (1979-2015). From composite analysis we found that a split jet over the Eastern South Pacific is beneficial for the formation of COLs. Depending on the characteristics of the southern jet streak, wave breaking processes are involved, and the majority of the COL events is associated to anti-cyclonic wave breaking equator-wards. More COLs occur in the Last Glacial Maximum (LGM) compared to present day conditions in two models (MPI-ESM-P and CCSM4) of the Paleoclimate Modeling Intercomparison Project (3rd phase; PMIP3). In both models the processes being involved in the COL formation are depicted realistically. The increasing number of winter COLs coincides with a shift of upper-level zonal winds, which facilitates the formation of the split jet structure over the Eastern South Pacific: The non-uniform global cooling during the LGM due to polar amplification induce a decrease of the subtropical jet and a speed up of upper-level zonal winds in the mid-latitudes of the Southern Hemisphere, and these shifts are particularly strong in the South Pacific region west of South America.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Reyers, Mark UNSPECIFIED orcid.org/0000-0001-7085-9345 UNSPECIFIED Shao, Yaping UNSPECIFIED orcid.org/0000-0002-2041-5479 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-132541
DOI:	10.1016/j.gloplacha.2019.102983
Journal or Publication Title:	Glob. Planet. Change
Volume:	181
Date:	2019
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	1872-6364
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Geosciences > Institute for Geophysics and Meteorology
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ROSSBY-WAVE-BREAKING; SOUTHERN-HEMISPHERE; VARIABILITY; CIRCULATION; PRECIPITATION; CLIMATOLOGY; IMPACT; CHILE Multiple languages Geography, Physical; Geosciences, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/13254