@InProceedings{CastroBona:2010:ImRoSe,
author = "Castro, Christopher Alexander Cunningham and Bonatti, Paulo",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)}",
title = "Impacts of the ross sea anomalous sea ice conditions on the
Southern Hemisphere atmosphere",
booktitle = "Posters",
year = "2010",
organization = "The Meeting of the Americas.",
publisher = "AGU",
keywords = "sea ice, global climate models, ocean, atmosphere interactions.",
abstract = "This work examines the impact, on the Southern Hemisphere
atmosphere, of anomalous sea ice extension in the Ross Sea, from
the standpoint of two opposite conditions: with reduced and
increased sea ice cover. To achieve this goal we have designed an
experiment with the Atmospheric General Circulation Model of the
Center for Weather Forecast and Climate Studies (AGCM-CPTEC/INPE).
The whole experiment was composed of three large ensembles, sized
with 60 members each, in order to achieve a significant
recognition of signal. One of them, the control experiment, was
forced with climatological sea surface temperatures and sea ice
cover. In the other two ensembles the sea ice cover distribution
in the Ross Sea was synthesized, from actual observed anomalies,
using the least and the most observed sea ice cover in the
1979-2005 time series of measurements. Those experiments were
named RO- and RO+, respectively. As expected, the sea ice cover
primarily affects the heat fluxes from the ocean. When the sea ice
layer is reduced (increased), the fluxes increase (reduce), and
this effect is more evident in sensible than latent heat fluxes.
The permanence for several weeks of those abnormal conditions is
able to alter locally the pattern of low-level temperature. The
results show positive (negative) temperature anomalies driven by
the abnormal positive (negative) fluxes of heat due to the imposed
sea ice perturbation. Thought the vertical penetration of the
temperature anomalies is shallow, not exceeding the 700 hPa level,
the sea ice cover anomaly imprints a discernible and permanent
anomaly in the near-surface temperature field, as can be seen
evaluating every member in the perturbed ensembles. A Principal
Component Analysis of the hemispherical patterns of low-level
temperature (925 hPa) identifies the local impact due to the sea
ice cover in the first and second eigenvectors, for the RO- and
RO+ respectively. The flux-driven anomalous patterns appeared
merged with hemispherical patterns due to the internal variability
of the model (CTRL). The difference between the CTRL and perturbed
pattern depicts that part of the anomalous pattern not due to the
internal variability. Among the most important results are the
indications of a relationship between the state of sea ice cover
in the Ross Sea and the low-level temperatures in subtropical and
extratropical South America. The present results indicate that the
relationship is such that the anomalies of temperature in South
America are of reverse sign regarding the polarity of the sea ice
anomaly in the Ross Sea.",
conference-location = "Foz do Igua{\c{c}}u",
conference-year = "8-12 Aug. 2010",
language = "en",
targetfile = "Christopher_IMPACTS.pdf",
urlaccessdate = "16 jun. 2024"
}