The atmospheric boundary layer characteristics over forest and pasture in the Amazon region
Gilberto
Fisch, Centro Tecnico Aeroespacial (CTA), gfisch@iae.cta.br
(Presenting)
The growth and development of the convective (CBL) and nocturnal (NBL) boundary layers over forest and pasture areas in the Ji-Paraná area (Rondonia) are investigated using observational data collected during the dry season 1994 (ABRACOS/RBLE experiment), wet season 1999 (Wet AMC/LBA-TRMM) and during transition period from dry-to-wet 2002 (RACCI-LBA/SMOCC). The data set consist of rawinsoundings, tethered balloon, surface automatic weather station and turbulent fluxes, SODAR, etc. The structure of the CBL over forest is almost independent of the period of the year (dry or wet) and its depth is typically around 1100-1200 m. The pasture CBL shows a very strong dependence on the soil moisture conditions, ranging from 1000-1100 m for the wet period and 2000-2200 m in the dry season. The surface sensible heat fluxes also responds to the soil moisture conditions. For the NBL, both sites presented the same behavior, with maximum development around 300 m for dry and wet conditions. Some case studies like cold front event, the coupling between a low level jet and shallow CBL during nighttime conditions, heat budget required for the erosion of the NBL, destruction of the CBL due to intense rainfall are also discussed.