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Description of Smoke Emission |
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Description of Smoke Emission |
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The GOES WF_ABBA is a modified version of the South American ABBA that has been used to monitor biomass burning in South America since 1995. The WF_ABBA is a dynamic multispectral thresholding contextual algorithm that uses the visible (when available), 3.9 micron, and 10.7 micron infrared bands to locate and characterize hot spot pixels. The algorithm is based on the sensitivity of the 3.9 micron band to high temperature sub-pixel anomalies. Once a hot spot pixel is located, the WF_ABBA incorporates ancillary data in the process of screening for false alarms and correcting for water vapor attenuation, surface emissivity, solar reflectivity, and semi-transparent clouds. This year, FLAMBÉ began to incorporate MODIS fire products from the University of Maryland in near real time. This data is incorporated into a smoke flux scheme for the eastern hemisphere thus allowing NAAPS to utilize a global smoke source function. While not at the temporal resolution as the WF_ABBA, the MODIS fire product has superior sensitivity and global coverage. For MODIS fire products, a step function diurnal cycle is used where daylight fires are reproduced hourly between 9 AM and 6 PM local time. Nighttime overpass data is propagated hourly for all remaining hours.
For model initialization such as NAAPS, we can estimate the net emission for an individual fire i, Ei as
where A is the total area burned, mf is the amount of fuel mass available for combustion in kilograms per square meter, fc is the average mass fraction of carbon in the fuel, cf is the combustion factor, and EFn is the average emission factor for particles, and T is the average time between burns. The AVHRR derived Global Land Cover Characteristics (GLCC) database (version 2.0) is used to assign surface biome type for each fire. A series of 10 fuel-load and emission factor categories are employed. ABBA fire size is used to derive burned area. For MODIS, one fourth of fire pixel is used.