@InProceedings{SolmanNuņeCabr:2006:PaI:Pr,
author = "Solman, Silvina and Nuņez, Mario and Cabr{\'e}, Mar{\'{\i}}a
Fernanda",
affiliation = "{Centro de Investigaciones del Mar y la Atm{\'o}sfera
(CIMA-CONICET/UBA)} and Ciudad Universitaria, Pabell{\'o}n II,
2do piso, 1828, Buenos Aires, Argentina (Solman and Nuņez and
{Cabr{'e})}",
title = "Regional climate change experiment over southern South America:
Part I: Present climate conditions (1981-1990)",
booktitle = "Proceedings...",
year = "2006",
editor = "Vera, Carolina and Nobre, Carlos",
pages = "429--439",
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 = "regional climate change, present day-climate, southern South
America.",
abstract = "A basic analysis is presented for a series of regional climate
change simulations over southern South America that were conducted
by the Centro de Investigaciones del Mar y la Atm{\'o}sfera
(CIMA) as a contribution to the Argentinean 2nd National
Communication of Climate Change Project. The regional model
MM5/CIMA was nested within time-slice global atmospheric model
experiments conducted by HadAM3 model. A 10-year control run and
two 10-year scenario runs (based on the SRES A2 and B2 emission
scenarios) were performed. In this paper we present the analysis
of the present-day climate (1981-1990). The main focus is to
evaluate the capability of the model in simulating the spatial
distribution and the seasonal cycle of precipitation and surface
air mean, maximum and minimum temperatures. Overall, the regional
model is able to capture the main features of the observed mean
surface climate over South America, its seasonal evolution and the
regional detail due to topographic forcing. A comparison of
seasonal average sea level pressure fields between the regional
model and NCEP reanalysis show that the subtropical anticyclones
over the Pacific and Atlantic Oceans are slightly shifted
poleward, as in HadAM3. The meridional pressure gradient at high
latitudes is overestimated with respect to NCEP reanalysis in
both, the HadAM3 and the regional model, particularly in winter,
being the synoptic activity more intense as well. The observed
regional patterns of surface air temperatures (mean, maxima and
minima) are well reproduced. Nevertheless, biases are mostly
within 3°C, being overestimated over central Argentina and
underestimated in mountainous regions during all seasons. Biases
in northeastern Argentina and southeastern Brazil are positive
during SON and negative in other seasons. In general, maximum
temperatures are better represented than minimum temperatures.
Nevertheless, warm bias is larger during DJF for maximum
temperature and during JJA for minimum temperature, mainly over
central Argentina. The broad spatial pattern of precipitation and
its seasonal evolution are well captured; nevertheless, there are
systematic errors in precipitation amounts, being the bias within
25 %. Particularly, the regional model overestimates the
precipitation over the Andes region in all seasons and in southern
Brazil during summer. Precipitation amounts are underestimated
over the Paran{\'a} River basin from fall to spring. Deficiencies
in the boundary conditions and surface processes may explain
deficiencies in representing precipitation and surface air
temperatures. For instance, more intense synoptic activity over
the Pacific storm-track region can explain larger amounts of
precipitation over the Andes. Moreover, warm bias over central and
northern Argentina during DJF is coherent with smaller
precipitation amounts, and thus, with soils too dry. Overall,
though there are systematic errors in the simulated present
climate conditions, we can conclude that the regional model is
capable in reproducing the main regional patterns and seasonal
cycle of surface variables. Nevertheless, though the length of the
simulation is relatively short, it is only possible to draw
conclusions about model performance with respect to mean
conditions. Moreover, a single realization is not enough in order
to build a complete evaluation of the simulation but it allows
identifying a degree of confidence of the dynamic downscaling
approach for the region. Finally, it is worth to mention that the
present reference simulation constitutes the basis to examine the
climate change simulations resulting from the A2 and B2 forcing
scenarios which are being reported in a separate study..",
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/2005/10.13.20.43",
url = "http://urlib.net/ibi/cptec.inpe.br/adm_conf/2005/10.13.20.43",
targetfile = "429-440.pdf",
type = "Climate change in the SH",
urlaccessdate = "28 abr. 2024"
}