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Summer heat waves in southeastern Patagonia: an analysis of the intraseasonal timescale
Author(s) -
JacquesCoper Martín,
Brönnimann Stefan,
Martius Olivia,
Vera Carolina,
Cerne Bibiana
Publication year - 2015
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.4430
Subject(s) - climatology , anomaly (physics) , teleconnection , advection , perturbation (astronomy) , geology , context (archaeology) , atmospheric sciences , environmental science , el niño southern oscillation , quantum mechanics , paleontology , physics , thermodynamics , condensed matter physics
We explore the occurrence of intraseasonal summer heat waves in southeastern Patagonia ( SEPG , 46°–52°S; 65°–70°W) since the late 19th century by means of the Twentieth Century Reanalysis version 2 ( 20CRv2 ). In total, we identify 201 cases for 1872–2010 using criteria of intensity and persistence. In SEPG , the corresponding intraseasonal temperature signals are centred around the first day of each cluster of days fulfilling those conditions (named day 0). The mean warm deviation lasts for approximately 2 weeks and exhibits a mean temperature peak of 4.3 °C on day 0 (the warmest day in the mean signal). In a regional context, the mean temperature perturbation associated with these heat waves affects a broad area on both sides of the Andes. The warming in SEPG is caused by temperature advection and enhanced radiative heating, following a high pressure system over southern South America ( SSA ). This atmospheric perturbation is embedded in a wave‐train‐like pattern along the South Pacific. As part of this pattern, a cyclonic anomaly progresses eastward over the Tasman Sea in Oceania, moving from southeastern Australia (day −6, causing a dry anomaly there) over New Zealand (day −3, inducing a wet anomaly on its Southern Island). The anomalous circulation triggered by the wave train leads thus to a teleconnection between SSA and Oceania, documented in a previous work for the interannual scale. Two thirds of the heat wave events are linked to enhanced ascent in the South Atlantic Convergence Zone ( SACZ ) and around one third of the events within 1957–2010 are associated with extreme absolute maximum temperatures observed at a station‐based record from SEPG . Finally, possible spatial modulations of the wave train pattern at the interannual and interdecadal timescales are discussed.