Effect of band-to-band coregistration on fire property retrievals

The impact of satellite band-to-band coregistration errors on fire retrievals from biomass burning has not been well quantified. However, the retrieval of fire temperature and area using a two-channel algorithm can be extremely sensitive to coregistration between the channels because fire sizes are generally much smaller than the sensor pixel resolution. Simulations are used to determine the magnitude of these errors for a range of spatial response shapes, including one case that is representative of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Presented are results that show typical sensor band-to-band coregistration errors of 10% to 15% are a dominant source of error in the retrieved fire properties. For example, a MODIS-type instrument with a 1-km horizontal spatial resolution and a 10% coregistration error would generate retrieval errors on the order of 150 K and 210% for a single retrieved fire temperature and fractional fire area, respectively. The retrieval errors, which depend on the position of the fire in the pixel, are asymmetric in the direction of the misregistration, and it is noted that this characteristic could be utilized in validation studies to flag or correct for coregistration errors.