Satellite remote sensing of fires, smoke and regional radiative energy budgets

Using satellite imagery, more than five million square kilometers of the forest and cerrado regions over South America are extensively studied to monitor fires and smoke during the 1985 and 1986 biomass burning season. The results are characterized for four major ecosystems, namely: (1) Tropical Rain Forest [TRF], (2) Tropical Broadleaf Seasonal [TBS], (3) Mild/Warm/Hot Grass/Shrub [MGS], and (4) Savanna/Grass and Seasonal Woods [SGW]. Using collocated measurements from the instantaneous scanner Earth Radiation Budget Experiment (ERBE) data, the direct regional radiative forcing of biomass burning aerosols are computed. The results show that more than 70% of the fires occur in the MGS and SGW ecosystems due to agricultural practices. The smoke generated from biomass burning has negative net radiative forcing values for all four major ecosystems within South America. The smoke found directly over the fires have mean net radiative forcing values ranging between -25.6 to -33.9 W/m/sup 2/ for 1985 and between -12.9 to -40.8 W/m/sup 2/ for 1986. These results confirm that the regional net radiative impact of biomass burning is one of cooling.