A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

BLACK CARBON COMPARATIVE ASPECTS FOR CLIMATECHARACTERIZATION OF RIO BRANCO - AC, BRAZILA. Fonseca Duarte 1 , P. Artaxo 2 , B. N. Holben 3 , J. S. Schafer 3 , I.F. Brown 41 Federal University of Acre – UFAC, Campus Universitário, BR-64, km 4, Distrito Industrial,CEP: 69.915-900, Rio Branco - AC, Brazil, alejandro@ufac.br2 University of São Paulo – USP artaxo@if.usp.br3 Goddard Space Flight Center – GSFC/NASA joschafe@pop900.gsfc.nasa.gov4 Woods Hole Research Center – WHRC (UFAC and UFF) fbrown@whrc.orgAbstractThe State of Acre is located in Northwestern Brazil. The climate of this region,Tropical Forest, must be observed throughout environmental disturbances such as theincreased biomass burning, deforestation and the highway construction (BR-317) openingtraffic to the Pacific Ocean. The objective of the present work consists in an evaluation ofatmospheric black carbon concentration (BC) related to other variables of the conventionalmeteorology. The meteorological data analysis (1970- 2002) reveals a correlated seasonalbehavior between rainfalls, temperatures, evaporation, atmospheric pressure and relativehumidity. Recent measurements (2000- 2002) of the smoke concentration (BC) in the localatmosphere reveal values up to (5 - 10) µg m -3 , for the rainy station, and up to (15- 30) µgm -3 , for the dry season. Comparable results were observed in Rondônia. Daily, the highestconcentrations occur at night, approximately between 17:00 and 09:00 hours. Theconcentrations are comparable to those calculated by INPE, based on the regional model ofgas and aerosol transportation ETA. Assuming, on average, that about 6 % of theatmospheric aerosols corresponds to BC, the total aerosol concentration in Rio Branco'satmosphere, in dry season - the period of intense biomas burnings in Amazonia- reaches300 - 500 µg m -3 . Similar values has been recorded in Alta Floresta in the past decade.This fact indicates that, probably, the local biomass burning in different places and thesmoke transportation across atmosphere contribute affecting all Amazonian regions.Irradiance and insolation measurements, however, show that PAR fraction for Rio Brancois practically the same all the year (0,40 ± 0,02), a different behavior than that of AltaFloresta.