@InProceedings{VillarroelJiménezRoseAcei:2006:ExTe,
author = "Villarroel Jim{\'e}nez, Claudia and Rosenbl{\"u}th L{\'o}pez,
Benjamin and Aceituno Gutierrez, Patricio",
affiliation = "Direccion Meteorologica de Chile (DMC), Departamento de
Climatologia, Av Portales 3450 , Estacion Central ,Santiago, Chile
(Villarroel, Claudia) and Universidad de Chile, Departamento de
Geofisica, Av. Blanco Encalada 2002, Santiago, Chile (Aceituno,
Patricio) (Rosenbluth, Benjamin)",
title = "Climate change along the extratropical West coast of South
America: extreme temperatures",
booktitle = "Proceedings...",
year = "2006",
editor = "Vera, Carolina and Nobre, Carlos",
pages = "487--489",
organization = "International Conference on Southern Hemisphere Meteorology and
Oceanography, 8. (ICSHMO).",
publisher = "American Meteorological Society (AMS)",
address = "45 Beacon Hill Road, Boston, MA, USA",
keywords = "climate changes, extremes temperatures, derived indicators, trends
and variability.",
abstract = "Climate change along the extratropical West coast of South
America: extreme temperatures The analysis of changes in the
frequency and intensity of extreme conditions occurring at the
daily time scale is highly relevant in the context of assessment
of long-term climate variability, as the occurrence of those
extremes typically has a large socioeconomic impact (episodes of
heavy rainfall, heat waves, cold spells, etc). However, this type
of assessment has progressed slower than those related with
changes in average conditions, due to severe limitation of daily
data availability. This study deals with long-term changes in the
occurrence of temperature extremes along the extratropical West
coast of South America. Record of homogenous daily data of extreme
temperatures (maximum/minimum) from 16 meteorological stations
located from 18°S to 53°S in Chile are used to assess changes in
the occurrence of temperature extremes along the extratropical
west coast during the period 1961-2003. Some of the indices used
for this assessment are: number of days with minimum temperature
below the percentile 10% (cold nights) or above the percentile 90%
(warm nights); number of days with maximum temperature below the
percentile 10% (cold days) of above the percentile 90% (warm
days); number of freezing days and length of periods with freezing
days. In the coastal areas of the northern portion of the
territory (18°S 33°S) the evolution of these indices are strongly
modulated by the anomalously warm conditions during El Niño
episodes, making quite useless the application of conventional
tool to assess slow climate changes. As an example, the daily
minimum temperature in Arica (18°S) was above the 90% percentile
during almost all the nights from 1 Dec. 1997 to 28 February 1998,
producing a severe impact. Then the annual and seasonal time
series of warm days and warm nights coastal areas of northern
Chile are characterized by marked spikes during El Niño episodes.
In addition to this interannual variability, some of the indices
reveal a significant decadal variability, denoting a shift toward
warmer conditions in the mid 70s in association with a change in
the phase of the Pacific Decadal Oscillation. This behavior is
particularly well defined in the frequency of cold nights (less
frequent in recent decades) and warm nights (more frequent in
recent decades) in the subtropical domain (18°S - 35°S). Thus, the
significant negative (positive) trend detected by a regression
analysis on the 1961-2003 evolution of annual frequency of cold
(warm) night disappear completely when the analysis is done
separately for the periods 1961-1975 and 1977 2003, indicating
that a climate shift rather than a climate trend is responsible
for the change. A significant negative tendency (between 0.1 - 0.5
°C/dec) in the daily temperature range (DTR) is observed in many
regions in the world (Easterling, at. al, 1997); in Chile the
results are consistent with global studies for the period
1961-2003. On the other hand, the frequency of days with frosts
(FD) prevail negative trend but non-significant to 95% of
confidence in most of the stations. The same it happens with the
maximum number consecutive days with frosts (CDF).",
conference-location = "Foz do Igua{\c{c}}u",
conference-year = "24-28 Apr. 2006",
language = "en",
organisation = "American Meteorological Society (AMS)",
ibi = "cptec.inpe.br/adm_conf/2005/10.14.13.20",
url = "http://urlib.net/ibi/cptec.inpe.br/adm_conf/2005/10.14.13.20",
targetfile = "487-490.pdf",
type = "Climate change in the SH",
urlaccessdate = "29 jun. 2024"
}