An Enhanced Contextual Fire Detection Algorithm for MODIS

Experience with the first 2 years of high quality data from the Moderate Resolution Imaging Spectroradiometer (MODIS) through quality control and validation has suggested several improvements to the original MODIS active fire detection algorithm described by Kaufman, Justice et al. [Journal of Geophysical Research 103 (1998) 32215]. In this paper, we present an improved replacement detection algorithm that offers increased sensitivity to smaller, cooler fires as well as a significantly lower false alarm rate. Performance of both the original and improved algorithm is established using a theoretical simulation and high-resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scenes. In general, the new algorithm can detect fires roughly half the minimum size that could be detected with the original algorithm while having an overall false alarm rate 10–100 times smaller. © 2003 Elsevier Inc. All rights reserved.

Impact of Deforestation on the proposed Mesoamerican Biological Corridor in Central America

This study uses the dry season NDVI of 1982, to 2000 derived from AVHRR to identify regions of substantial deforestation in Central America. High-resolution nested grid simulations over the identified regions of deforestation using the Colorado State University Regional Atmospheric Modeling System (RAMS) are used to examine cloud formation under three scenarios: 1. region completely forested; 2. current land use conditions; and 3. deforested conditions. In the deforestation scenario the locations of the proposed Mesoamerican Biological Corridor are kept forested with pasture conditions outside the protected areas. These simulations will help identify locations where high deforestation could make the proposed corridor climatically unstable. The study also uses MODIS and GOES satellite data to understand how land use currently influences cloud formation and their properties. Preliminary satellite data analyses show that for the dry season month of March cumulus cloud frequency is nearly one and a half times higher over forests compared to grasslands irrespective of elevation. Cumulus clouds over forests are also more likely to be drizzling than over grasslands. Model simulations show that with pastures surrounding protected forests and corridors, several locations of the corridor will have suppressed cloud formation. Further simulations are being conducted and results from statistical analysis of a set of simulations and comparison against satellite observations will be presented.
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