An algorithm to address the MODIS bowtie effect

A snow cover mapping and snowmelt runoff forecasting system is currently being operated at the United States Department of Agriculture – Agricultural Research Service (USDA-ARS) Jornada Experimental Range. Snow-covered area is being used as an input for snowmelt runoff forecasting and has been traditionally derived from National Oceanic and Atmospheric Administration (NOAA) advanced very high resolution radiometer (AVHRR) channels 1 and 2. Both the snow maps and the snowmelt runoff forecasts are being sent to water resources agencies and companies for decision making in water management. The quality of the snow maps can be improved using the moderate resolution imaging spectroradiometer (MODIS) instrument on board the Terra platform. MODIS channels 1 and 2 are centered in wavelengths similar to those of AVHRR channels 1 and 2, but with 250 m resolution instead of 1 km resolution of AVHRR channels. The recent implementation of MODIS data has been complicated by the so-called "bowtie effect" of the MODIS instrument, which causes an overlap of the satellite field of view, producing a data repetition. This effect increases with the distance from nadir and can be especially dramatic at the edge of the image.