FengYun-3C VIRR Active Fire Monitoring: Algorithm Description and Initial Assessment Using MODIS and Landsat Data

The Visible and Infra-Red Radiometer (VIRR) is an improved third-generation earth observation sensor that has channels ranging from the visible to thermal bands and is carried on board the Chinese FengYun-3C satellite. The VIRR instrument provides full global coverage at a spatial resolution of 1 km. It is neither appropriate nor correct to simply duplicate the parameters used in algorithms designed for other sensors. Hence, this paper proposes an active fire-monitoring algorithm designed for the VIRR sensor. A newly proposed concept—the "infrared channel slope"—is employed in the algorithm, which can detect active fire pixels by identifying deviations in their mid-infrared and thermal infrared brightness temperatures. "Dynamic thresholds" are also used to allow the algorithm to adapt to different situations. Different fire events that occurred in different parts of the world between 2014 and 2016 are selected to test the robustness of the algorithm. The testing consists of two parts: a rough assessment using products of a similar spatial resolution and then a detailed assessment based on fine spatial resolution images. In the rough assessment part, the results are compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) Fire and Thermal Anomaly product (MOD14A1) and the China Meteorological Administration's Global Fire References (GFR) products from the National Satellite Meteorological Center. In the detailed assessment, imagery acquired by the Landsat-7/Enhanced Thematic Mapper Plus and the Landsat-8/Operational Land Imager is used. The MODIS and Landsat data are utilized as reference data to validate the accuracy while the comparison with the GFR products is carried out to demonstrate the advantages of this method. The assessment demonstrates that the algorithm produces comparable results to those obtained using MOD14A1 and is a significant improvement compared with GFR.