Development of a new thermal snow index and its relationship with snow cover indices and snow cover characteristic indices

In this study, we have developed a new thermal snow index viz. S3 thermal snow index (S3TSI) and determined its relationship with two existing thermal snow indices (i.e., normalized difference snow thermal index (NDSTI) and normalized difference thermal snow index (NDTSI)) and with snow cover indices (i.e., normalized difference snow index (NDSI) and S3) and snow cover characteristic indices (i.e., snow grain size index (SGI) and snow contamination index (SCI)) for two different sites such as bare snow cover and snow cover mixed with vegetation, respectively, based on Pearson’s correlation coefficients. Whereas NDSTI uses blue band, NDTSI incorporates NDSI. With this analogy, we have developed “S3TSI” by substituting S3 for NDSI since S3 better demarcates snow cover mixed with vegetation. The study was conducted in snow cover test sites of the Chenab basin, Western Himalayas using LANDSAT-8 Operational Land Imager and Thermal Infrared Sensor data of November 2013. The investigation revealed that S3TSI exhibits considerably higher correlation with NDTSI and also with NDSI and S3 in either site except in the case of snow cover mixed with vegetation where NDTSI correlates better with NDSI. All the three thermal snow indices exhibit very high correlation with the snow cover indices in snow cover mixed with vegetation as compared to bare snow cover. However, the thermal snow indices show weak correlation with the snow cover characteristic indices as compared to the snow cover indices in either site. The findings demonstrate the significance of the new thermal snow index as compared to NDSTI and NDTSI.