Abstract ID: 470

Water vapor fluxes and convergence in Amazon Basin during two contrasting years.

The climatological charts for the months of December, January and February (the rainy season) show that water is transported into the Amazon Basin across the northern coast of the South American continent between Maranhão state in Brazil and eastern Venezuela. During these austral summer months water is transported out of the Amazon region into Bolivia and central Brazil across 10°S. More than 80% of these transports occur in the lower troposphere between 1000 and 700 hPa levels. The water vapor fluxes integrated in the vertical into a rectangular area bounded by Equator in the north, 15°S in the south, 45°W in the east and 70°W in the west are calculated for the DJF, MAM, JJA, SON seasons and for the whole year for the years 2005 and 2007 and are compared with the climatology for the period 1968-96. 1995 is a well-advertised dry year and 2007 is a normal year in the Amazon Basin. The annual mean net convergences of water vapor flux in the rectangular region in the two years were almost equal and are slightly (9%) less than the climatology, which is approximately 5 mm/day. (The difference between the annual average rainfall in the basin of approximately 7 mm/day and the 5 mm/day convergence in the atmosphere comes from evapotranspiration or “local recycling” by the tropical forest.) Approximate estimates show that more than 50% of the water vapor transport into the Amazon basin is from the North Atlantic. The trade winds south of the North Atlantic subtropical high are responsible for the transport. The seasonal differences in the H2O transport and convergence are also discussed.

Session:  Feedbacks to Climate - Land cover, surface hydrology, and atmospheric feedbacks. (B)

Presentation Type:  Oral