Snow cover trend analysis using Interactive Multisensor Snow and Ice Mapping System data over Turkey



The daily snow cover data from Interactive Multisensor Snow and Ice Mapping System (IMS) by National Oceanic and Atmospheric Administration's National Environmental Satellite Data and Information Service (NOAA/NESDIS) covering the 2004–2012 time period is used in this study. In the first part of the study, daily IMS product is validated over Turkey using daily ground truth snow depth measurements from 219 climatological and synoptic sites. The categorical statistics of probability of detection (POD) and false alarm rates (FAR) are provided both for whole Turkey and with respect to geographical sub-regions. The overall POD and FAR amounts for Turkey are obtained as 73.55 and 25.11%, respectively. The performed analysis indicates an increase in IMS accuracies as the snowpack depth at the stations increase. In the second part of the study, the nonparametric Mann-Kendall test is performed to analyse the snow cover trend over Turkey with respect to sub-regions considering the whole year and each season separately. A negative trend in snow-covered area percentage is obtained for Turkey at the significance level of α = 0.05. From the seasonal perspective for Turkey, negative trend for spring and summer seasons, positive trend for autumn season and combination of negative and no trend for winter season are obtained at the same significance level. Almost the same results are valid for the sub-regions with some local and seasonal variations.