Clima do Hemisfério Sul há 1,080 milhão de anos: impacto do derretimento da geleira Antártica

• Autor(a) principal: Silva, Alex Santos da
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5262
• topic: Climatologia; Hemisfério sul; Geleira Antártica; Mudanças climáticas; Hidroclimatologia; Climatology; Southern hemisphere; Antarctic Glacier; Climate change; Hydroclimatology; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::METEOROLOGIA::CLIMATOLOGIA

The Earth s climate system is influenced by the topography configuration, whose importance is based on the characterization of the dynamic and thermodynamic aspects of the atmosphere and ocean. In this sense, the study aims to investigate the oceanic and atmospheric processes associated with the western Antarctic ice sheet collapse, which occurred 1.080 million years (ka) ago. Thus, two simulations were performed with the coupled climate model SPEEDO: a) the control simulation (CTRL) under current conditions and, b) forced simulation (1080ka), inserting the topography of 1.080 ka ago. Both simulations are conducted in the 2 CO atmospheric concentration of 380 ppmV. In the ocean circulation, the 1080ka simulation results show variations of salinity and temperature in relation to CTRL, at all ocean levels. Forcing contributed to an increase of approximately 1.4 °C and 1.6 °C in the sea surface temperature of the Ross and eastern Antarctic seas, plus the intensification of oceanic heat flux in the South Atlantic Ocean. On the other hand, there was an increase of 20 TW heat flow towards the north Pacific Ocean. These oceanic variations lead to changes in atmospheric circulations. The air temperature in the 1080ka simulation was 6.5 °C higher than CTRL in the Ross Sea region, contrary to the eastern region of Antarctic, where there was a decrease of 4.5 °C. In the precipitation field, there were an increase of approximately 160 mm/year in the Antarctic Peninsula and a decrease near 80 mm/year in the South Atlantic Ocean. The wind, at low levels, intensified in the South Atlantic anticyclone, moving towards South America continent. At high levels, the westward fluxes were weakened by the lower thermal gradient in the extratropical region. Although an intermediate complexity climate model was used, it was able to represent the main mass conservation mechanisms of the atmosphere and oceans.