Aspectos da termodinâmica da camada limite atmosférica no oeste da Amazônia durante a estação chuvosa: experimento WET AMC/LBA

Abstract

Results from LBA/TRMM Wet Season 1999 (Large Scale Biosphere-Atmosphere Experiment in Amazonia Tropical Rainfall Measurement Mission) are discussed. The measure had been made simultaneously in two experimental sites: native forest (10° 5'S; 61° 55'W; 120m) and pasture (10° 45'S; 62° 21' W: 290m), in Rondônia state. The climatic conditions during the experiment had been really typical of rainy season. The precipitations, in its majority, had been associates to the instability lines. The duration of the rain periods depends on the origino f these lines that can be: local, East Rondonia or the Atlantic coast. The rainy weather make disappear the contrast Forest/pasture, in terms of water vapor and energy budget, and the Atmospheric Boundary Layer (ABL) in the two sites became similar. The average thickness for example in the Forest was 599m and in the pasture 526m. The winds inside the ABL had been moderate and some nocturnal jets (about 10m.s-1) are observed. The Wind direction had a great temporal variability. The daily cycles of temperature and the humidity are easilydistinguished, except in rainy days. Significant differences Forest/pasture had not been found. In the ABL scale the Sky cover doesn’t play na important role and the difference forest-pasture are small. In domain of ABL had foound importants differences in Forest between Sky clear days (CC) and overcastting days (CN) in average 2,0K in potencial virtual temperature(0v) and 1,5g.Kg-1 in specific humidity (q). CN days are more humidity. In pasture significant differences had been found at affternoon in specific humidity and 0v. In this site in CC days average q is 16,0g.kg-1 at affternoon, and CN days 14,5g.kg-1. In this fact can be relationed to air warmer 4,0K in CC days comparing CN days. It’s increasing the amount water vapor in CC days.