Time Evolution of the Nocturnal Boundary Layer Over Amazonia
Rosa Maria
Nascimento dos
Santos, CPTEC/INPE, rosa@cptec.inpe.br
(Presenting)
Gilberto
Fernando
Fisch, IAE/CTA, gfisch@iae.cta.br
The CLN time evolution was studied based on vertical profiles of potential temperature, humidity (q) and wind (direction and speed), gotten from soundings with tethered balloon, over 3 sites (forest, RM and FNS), during the field experiments wetAMC-LBA (wet season) and RBLE3 (dry season). Mean characteristics – depth (hi), temperature on the top of CLN, thermal discontinuity, and the intensity nocturnal inversion – were determined for these two periods, and a comparative study was carried out. During the dry season the CLN was deeper over the forest – between 180 m (at 6 p.m.) and 420 m (at 5 a.m.), however the temperature on CLN top was 1.4 K higher over the pasture than over the forest. Also, strongest nocturnal inversion regularly happened over the pasture, with intensity peaking at 7 p.m. (50.5 K.km-1), indicating greatest stability over this site. Nevertheless, for the wet period the CLN was shallower over all sites (forest and deforested areas), and it revealed a more pronounced development over the deforested areas, particularly Rolim de Moura (~ 215 m at 7 a.m. and 296 m at 6 a.m.). Temperatures on the top layer tended to be higher at deforested than at forested sites (by 1.3 K at FNS, and 1.5 K at RM).