Spatiotemporal Changes in Snow-Cover related to the Land Surface Temperature over Central Alborz

The area, covered by snow or snow-cover variations, is one of the important factor in climatologic and hydrologic studies, that could be also useful and applicable in water management and environmental studies, specifically when it is combined with topographic characteristics. In this research Land Surface Temperature (LST) and snow-cover interactions were considered. These environmental indicators interactions, combined with focal topographic characteristics such as slope, play a major role in snow-cover persistency. As a result, the influences of these factors had taken into account in central Alborz mountainous belt in Iran northern boundary. To achieve this goal, snow-cover (SC) and land surface temperature (LST) obtained from Aqua and Terra satellite images that are carrying Modis sensor, used in a the temporal range of 2003 up to 2018. Snow cover data with spatial resolusion of 500m analyzied using python programming language. The analysis performed related to the aspect as a major topographic characteristic in the scope of terrain modeling with using moving window and cell by cell raster analysis thechniques. The result, shows a strong relationship between terrain aspect and snow coverage in the central sector of Alborz Mountains. Land surface temperature and snow-cover had an inverse trend, specifically during winter and fall seasons. June LST (Khordad) was high according to the higher zenith angle of the sun in this period of year. There is a clear gap between the LST values of northern and southern aspects of central Alborz that could be result of mountain orientations to the sun rays, higher humidity levels and denser vegetation cover in the northern part. Southward areas, show higher temperature in almost all months. Directional analysis of LST, demonstrated, that maximum levels of LST are observed in the south-faced and specifically southeastward area and the minimum levels observed in northeastward and specifically northward area during all months. Southward area of the alborz mountainous wall, located at the latitude band of 36N, experienced a higher sun ray incident angle and thus having higher LSTs in southern and southeastern parts. Finally in almost all temporal periods (including month, season and year) higher LSTs in southern aspects (South, Southeast and southwest) in compared to northern one (North, Northeast and northwest) has been observed.