Cloud masking and fire detection algorithms using NOAA-AVHRR data - A case study over central Himalayan Region
Yogesh Kant, Gopal Biswas, V. Krishna Prasad, K. V. S. Badarinath and S. K. Bhan National Remote Sensing Agency, Department of Space, Government of India, Balanagar - 500 037 Biomass burning associated with trace gas emissions is an important source of trace gas emissions. The major cause of uncertainty in determining the contribution of biomass combustion to trace gas emissions and their environmental impact is due to lack of information on the extent of area burnt, intensity of fires along with the biomass characteristics. Fire detection through conventional means suffers from practical problems and it has been well recognized that satellite data can be used effectively for detection of active fires and scars from the biomass burning plumes. NOAA AVHRR satellite data has five spectral channels (mm) viz., 0.58-0.68 (visible), 0.72-1.10(near infrared), 3.55-3.93 (mid-infrared), 10.3-11.3 (thermal infrared) and 11.5-12.5 (thermal infrared). Although, there have been studies on forest fire detection using thermal channels, the impact of clouds has been neglected. In the present study, an attempt has been made to test one of the fire detection algorithms through the combined use of middle and thermal infrared channels of NOAA-AVHRR satellite data. Two cloud screening algorithms have been attempted in the study. In the first method, a cloud-masking filter using channel five and channel one has been employed. In the second method, from the channel four, using a threshold value, the contaminating pixels are eliminated. Fire detection has been done using the brightness temperature difference between the channel three and channels four using the reference temperature difference threshold value. The methodology has been applied on AVHRR data over Central Himalyan forest area where large devastating fire occurred during May/June, 1995 affecting nearly 4,869 sq. km area. Using the above data, cloud screening along with fire detection algorithms have been implemented and a map showing the extent of active fire zones has been generated. Results of the study suggest the potential use of AVHRR satellite data in monitoring the fire events. | ||
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