HR: 1400h
AN: GC23A-11    [Abstracts]
TI: Effective Temperature Like an Indicative of Global Warming at Rio Grande do Sul
AU: * Berger, A P
EM: anaberger@furg.br
AF: Nisia Krusche, Departamento de Geociéncias - FURG Caixa Postal 474, Rio Grande, RS 96201-900, Brazil
AU: Krusche, N
EM: nkrusche@furg.br
AF: Nisia Krusche, Departamento de Geociéncias - FURG Caixa Postal 474, Rio Grande, RS 96201-900, Brazil
AB: The concept of effective temperature has been proven valuable in studies of climate changes and global warming. Pielke (2004) has shown that monitoring the moist static energy, which is a function of temperature and moisture content in the air, is a more proper metric to assess surface global warming. The effective temperature is proportional to the moist static energy by the specific heat content of the air at constant pressure. Since global warming is not homogeneous over the planet, we considered a limited area, the southernmost state of Brazil, Rio Grande do Sul. This region was selected due to the importance of cattle raising, agriculture, and fishery, as main economical activities. All those activities depend strongly on climate variations. We applied the concept of effective temperature to evaluate both the local warming and the contribution of moisture to it. The air temperature and specific humidity data was provided by the NCEP/NCAR Reanalysis, for the region from 27°S to 34°S, and from 49°W to 58°W, from 1948 to 2005. In an early work, we demonstrated that actual measurements in three places within the region are not similar to the Reanalysis data, although their anomalies are. Evaluation of the rate of increase of temperature, humidity, and effective temperature anomalies was performed, in each grid point, using linear regression. Moreover, Hovmoller diagrams were constructed for each latitude. Those analyses led to the conclusion that a real increase exists in all of the variables. The average effective temperature rate of increase was 0.5 °C per decade, although it is smaller inland and at the north coast, while the temperature rate of increase is larger in the south, and the humidity one, in the center and south. The largest effective temperature amplitude for the annual averages was in the north, but large values also occurred near to the ocean. The temperature presented larger amplitudes mostly in the coast, while the humidity varied more in the north region. Contributions to the effective temperature due to the humidity term varied from 54 to 80%, except for a point inland, in the south. Therefore, most of the warming in the southernmost region of Brazil, in the period from 1948 to 2005, was due to an increase of specific humidity. It has been suggested that this raise was due to the high number of El Nino occurrences during the 1990's. These phenomena produce a change in the surface circulation which favors the incursion of moist warm air from the northwestern region of South America to the southern Brazil.
UR: http:www.meteorologia.furg.br
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1630 Impacts of global change (1225)
DE: 1637 Regional climate change
DE: 5739 Meteorology (3346)
DE: 9360 South America
SC: Global Climate Change [GC]
MN: 2007 Joint Assembly