Nocturnal boundary layer over an Amazonian pasture area

This paper discuss the characteristics of the nocturnal boundary layer (NBL) and the prevailing turbulent regime during the campaign DRY-to-WET, dry to wet season transition period (September-November) of RaCCI/LBA 2002. Measurements of radiosonde (RS), tethered balloon (TB), automatic weather station (AWS) and SODAR (remote sensing device) were made over the pasture site (Faz. Nossa Senhora Aparecida - 10 ° 45'S, 62 ° 21'W, 290 m) in the region of Ouro Preto D'Oeste - RO. The turbulent flow regime was determined using the Monin-Obukhov parameter. The NBL heights (RS, BC and SODAR), ranging from 156.3 ± 57.9 m at sunset up to 301.0 ± 124.5 m on the early morning of the next day, showed similarity with data already obtained during the dry season over the same region. However the characteristic of the atmospheric stability was similar to previous data collected during the wet season. In other words, during the transition period from dry to wet conditions, the atmosphere is not fully established, showing characteristics of both seasons: the height of the NBL is similar to the ones during dry period measurements while the atmospheric stability presents the same behavior as during the wet period. .

nocturnal boundary layer; transition season; turbulent regime