Hotspot and NDVI differencing synergy (HANDS): A new technique for burned area mapping over boreal forest

Biomass burning releases significant amounts of trace gases and smoke aeros ol into the atmosphere. This has an impact on the Earth's radiation budget, the magnitude of which has not yet been well quantified. Satellite remote sensing is well suited to assessing the area of biomass burning, a prerequi site for estimating emissions at regional and global scales. Commonly used satellite-based techniques for measuring burned areas include thermal hotsp ot detection and multitemporal NDVI analysis, each having several limitatio ns. Here we present a new, hybrid approach for boreal burned area mapping c alled HANDS, or hotspot and NDVI differencing synergy. The automated techni que was tested using satellite data covering Canada for the 1995 and 1996 f ire seasons, and comparing results with official burned area statistics and conventional fire surveys. HANDS computed a national burned forest area of 6.8 million ha in 1995 and 2.0 million ha in 1996, corresponding favorably to Canadian Forest Service estimates of 7.1 million ha and 1.9 million ha, respectively. Moreover, in most cases, the technique accurately delineated the boundaries of individual burns and identified some burns that were mis sed with conventional mapping. When employed in conjunction with NOAA-AVHRR imagery, HANDS provides a consistent means of mapping large burns (>10 km( 2)), which are characteristic for the boreal forest. New generation sensors (e.g., SPOT VEGETATION, Terra MODIS) should enable its successful applicat ion to a wider range of environments. (C) Elsevier Science Inc., 2000.