MODIS snow cover mapping accuracy in a small mountain catchment – comparison between open and forest sites

摘要

Numerous global and regional validation studies have examined MODIS snow mappingaccuracy by using measurements at climate stations, which are mainly at opensites. MODIS accuracy in alpine and forested regions is, however, still notwell understood. The main objective of this study is to evaluate MODIS(MOD10A1 and MYD10A1) snow cover products in a small experimental catchmentby using extensive snow course measurements at open and forest sites. TheMODIS accuracy is tested in the Jalovecky creek catchment (northernSlovakia) in the period 2000–2011. The results show that the combined Terraand Aqua images enable snow mapping at an overall accuracy of 91.5%. Theaccuracies at forested, open and mixed land uses at the ?ervenec sitesare 92.7%, 98.3% and 81.8%, respectively. The use of a 2-day temporalfilter enables a significant reduction in the number of days with cloudcoverage and an increase in overall snow mapping accuracy. In total, the2-day temporal filter decreases the number of cloudy days from 61% to26% and increases the snow mapping accuracy to 94%. The resultsindicate three possible factors leading to misclassification of snow asland: patchy snow cover, limited MODIS geolocation accuracy and mappingalgorithm errors. Out of a total of 27 misclassification cases, patchy snowcover, geolocation issues and mapping errors occur in 12, 12 and 3 cases,respectively.