Bendix, J.; Trachte, K.; Palacios, E.W.; Rollenbeck, R.; Göttlicher, D.; Nauss, T. & Bendix, A. (2011): <b>El Niño meets La Niña - anomalous rainfall patterns in the "traditional" El Niño region of southern Ecuador </b>. <i>Erdkunde</i> <b>65</b>, 151-167.
Resource Description
Title:
El Niño meets La Niña - anomalous rainfall patterns in the "traditional" El Niño region of southern Ecuador
FOR816dw ID:
990
Publication Date:
2011-07-04
License and Usage Rights:
Resource Owner(s):
Individual:
Jörg Bendix
Contact:
email:
bendix <at> staff.uni-marburg.de
Faculty of Geography
Deutschhausstraße 10
Philipps University of Marburg
Laboratory for Climatology and Remote Sensing
35032 Marburg
Germany
Individual:
Katja Trachte
Contact:
email:
katja.trachte <at> b-tu.de
Atmospheric Processes
Burger Chaussee 2
Campus Nord, LG 4/3
Brandenburg University of Technology Cottbus-Senftenberg
03044 Cottbus
Germany
Individual:
Enrique Wilson Palacios
Contact:
email:
webmaster <at> tropicalmountainforest.com
Individual:
Ruetger Rollenbeck
Contact:
email:
rollenbe <at> staff.uni-marburg.de
Laboratory for Climatology and Remote Sensing
Faculty of Geography
Philipps University of Marburg
Deutschhausstr. 10
35032 Marburg
Germany
Individual:
Dietrich Göttlicher
Contact:
email:
dietrich.goettlicher <at> staff.uni-marburg.de
Faculty of Geography
Deutschhausstr. 10
Laboratory for Climatology and Remote Sensing
Philipps University of Marburg
35032 Marburg
Germany
In this paper, the central Pacific cold event of 2008 and its exceptionally warm conditions in the eastern tropical <br/>
Pacific are analyzed by using rainfall data of south Ecuadorian meteorological stations, sea surface temperatures in the El <br/>
Niño3 and 1+2 regions, and simulations with the Weather Research and Forecasting (WRF) model. It can be shown that El <br/>
Niño-like rainfall conditions with severe inundations occur particularly in the coastal plains of southern Ecuador while a <br/>
central Pacific cold event prevails. In contrary to previous situations, positive rainfall anomalies as a result of El Niño-like <br/>
conditions in the El Niño1+2 region during the 2008 La Niña event occurred in both regions, the coastal plains and the <br/>
highlands, for the first time. A detailed analysis of the ocean-atmosphere system during episodes of heavy rainfall reveals <br/>
typical El Niño circulation and rainfall patterns as observed during previous El Niño events for the coastal area and La <br/>
Niña-like conditions for the highlands. The spreading of Pacific instability in the Niño1+2 region to the eastern escarpment <br/>
of the Andes could be the result of a temporary eastward shift of the Walker circulation. The unusual combination of El <br/>
Niño-like conditions in the eastern tropical Pacific during a La Niña state in the central Pacific is the newest indicator for <br/>
an impact mode shift regarding severe rainfall anomalies during El Niño/La Niña events in the traditional El Niño area <br/>
of southern Ecuador since the end of the last century. Since 2000, El Niño events unexpectedly provide below average <br/>
rainfall while central Pacific La Niña conditions generate exceptional severe flooding in the normally drier coastal plains. <br/>
The novel sea surface temperature (SST) anomaly dipole structure between the eastern and central/western tropical Pacific <br/>
and the weakening of El Niño events since 2000 could be due to natural decadal oscillations in the El Niño background <br/>
state, the Pacific Decadal Oscillation (PDO). However, the observed atmospheric patterns and the recent increase of the <br/>
SST anomaly difference between the central and the eastern tropical Pacific resemble structures that also result from climate <br/>
change simulations.
Keywords:
| South Ecuador | el nino | la nina | ENSO | rainfall anomalies | sea surface temperature anomalies |
