Navegando por Autor "Justino, F."
Agora exibindo 1 - 2 de 2
- Resultados por Página
- Opções de Ordenação
Item Atmospheric susceptibility to wildfire occurrence during the Last Glacial Maximum and mid-Holocene(Palaeogeography, Palaeoclimatology, Palaeoecology, 2010-09-01) Justino, F.; Barbosa, H. A.; Peltier, W. R.Based on coupled climate model simulations the impact of anomalous climate forcing on the environmental vulnerability to wildfire occurrence is analyzed. The investigation applies the Haines Index (HI), which indicates the potential for wildfire growth by measuring the stability and dryness of the air. Three simulations have been analyzed: for Last Glacial Maximum (LGM), the mid-Holocene (MH) and present day (MOD) conditions. The results indicate that for present day conditions, the HI is a useful tool to identify areas with high susceptibility for fire occurrence, such as the west coast of the United States and the central part of South America. Analyses for the glacial epoch demonstrated that in respect to MOD conditions, the HI is intensified in Africa and south Asia. It is reduced, however, in Australia, the west coast of North America, Europe and in northern Asia. During the mid-Holocene, the atmospheric conditions were likely more favorable for fire occurrence over North America, sub-Saharan Africa and a large part of Eurasia and South America. In the contrary, Australia, northern Africa and the northern part of South America seem to have been less susceptible to intense fire as compared to current conditions. These findings very closely match paleofire inferences based upon charcoal analyses.Item Influence of boundary conditions on the Southern Hemisphere atmospheric circulation during the last glacial maximum(Revista Brasileira de Meteorologia, 2008-12) Justino, F.; Souza, E.; Amorim, M. C.; Dias, P. L. Silva; Lemos, C. F.Based upon coupled climate simulations driven by present day and glacial boundary conditions, we demonstrate that although the ice sheet topography modifications during the glacial period are primarily placed in the Northern Hemisphere (NH), a climate simulation that employs the ICE-5G glacial topography delivers significantly enhanced climate anomalies in the Southern Hemisphere (SH) as well. These conditions, in association with climate anomalies produced by the modification of the atmospheric CO2 concentration characteristic of the Last Glacial Maximum (LGM) interval, are shown to be the primary forcing of the SH climate during this epoch. Climate anomalies up to -6°C over the Antarctic region and -4°C over South America are predicted to occur in respect to present day conditions. Accompanying the SH cooling in the LGM simulation there exists a remarkable reduction in the specific humidity, which in turn enforces the overall Southern Hemisphere cooling due to the weaker greenhouse capacity of the dry atmosphere.