VIIRS snow mapping accuracy at regional and catchment scale

The Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover product is well-suited for hydrological applications due to its reliable accuracy and daily accessibility. However, the MODIS snow product is anticipated to be replaced by the Visible Infrared Imaging Radiometer Suite (VIIRS) snow cover product soon. Therefore, a thorough and accurate evaluation of this product is essential to ensure its suitability for future hydrological applications.

This study aims to assess the accuracy of the VIIRS snow product across Austria (observations at 631 climate stations) and within a small experimental catchment, the Jalovecký Creek catchment in northern Slovakia, using extensive snow course measurements conducted at both open and forested sites between January 2012 and August 2021. In the VIIRS snow cover product, the Normalized Difference Snow Index (NDSI) is used for snow detection. A threshold of NDSI (T_NDSI) is needed for distinguishing snow from snow-free land. Based on the daily snow depth observations from climate stations/snow course locations, the best NDSI threshold (BT_NDSI) is firstly determined through a detailed sensitivity test (100 different T_NDSI from 0.01 to 1.0 with a step of 0.01). The overall accuracy (OA) of VIIRS data is then evaluated based on the BT_NDSI and by comparison with the daily C6 MODIS snow cover dataset. The assessment of the BT_NDSI/OA is performed for all climate stations/snow course locations, as well as for different groups of stations representing different physiographic and land cover conditions. The results will compare the seasonal and topographical variability of mapping accuracy and the mapping threshold. We will also compare the mapping accuracy at open and forested sites.

 

This work was supported by the Slovak Research and Development Agency under Contract No. APVV-23-0332, the VEGA Grant Agency No. 2/0019/23, and the Danube Region Programme: DRP0200156 Danube Water Balance.