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

A Comparison of Satellite Fire Products and In Situ Observations inSouthwestern Amazonia: A Case Study in Acre, Brazil.D. Selhorst 1 , I.F. Brown 2 , E.R.H. Mendoza 3 E. Prins 4In southwestern Amazonia of Brazil, Bolivia and Peru, fires have already causedenvironmental, social and economic problems. With the future axis of integration(Avança Brasil) implanted in the region, fire frequency will increase, if patterns in otherparts of Amazonia serve as a guide. This study offers a preliminary analysis of theaccuracy of fire monitoring in 2001 by GOES-8 and NOAA-12 satellites through thecomparison with field data, digital imagery, and official data. The field data are from anenforcement campaign of PROARCO/IBAMA-Acre with georeferenced fire scarsobserved from helicopter over flights. An over flight with INPE/IBAMA continuousvideography covered over 400 km 2 where fire scars were counted and then extrapolatedfor the state. These data were also compared with official burn permits from IBAMA andIMAC, the State Environmental Agency. For 2001, 7100 permits for slash and burn weregranted for the entire Acre State. Many fires, accidental and deliberate, are not associatedwith permits. Videographic data indicated > 6800 fires before 19 September. Thenumber of fires extrapolated from the IBAMA enforcement flights is >2700. Hot pixelsfor the period of July to November 2001 from AVHRR/NOAA-12 indicate 830 (springWeb). A partial GOES-8 half-hourly fire pixel database for the period 15 Septemberthrough 31 October reported 1700 processed fire pixels This analysis did not includesaturated, cloudy, or other possible fires which account for a large fraction of the totalnumber of GOES-8 detected fire pixels. During the traditional period of intense burningin Acre (1-11 September), two analyses of NOAA-12 showed