Snow cover plays an important role in hydrological modelling and influences the energy balance. Daily Moderate Resolution Imaging Spectroradiometer (MODIS) snow products are widely used for snow cover monitoring; however, the cloud cover causes a discontinuity in spatial and temporal scale. Therefore, we have implemented a composite (five-step) methodology for cloud removal over the Karakoram and Himalayan (KH) region during 2000–2019. The cloud-gap-filled snow cover area (SCA) was compared with Landsat-8 data, and the relationship with in situ observations (snowfall and temperature) was examined. The annual SCA illustrates an increasing trend for the entire KH except in the eastern Himalayas. The snow cover day and nine snow cover timing indices were assessed to explore the snow cover characteristics. The relationships between SCA and meteorological variables were evaluated, suggesting a higher correlation with temperature and shortwave radiation. A sensitivity analysis was performed, indicating higher sensitivity of SCA to radiation than to other selected variables.

The regional scale mass change provides a substantial understanding to the influence of climate change on the glacier surface. However, the scarce ground observations and large spatial extent limit the use of field-based mass balance estimation. In this study, the Gravity Recovery and Climate Experiment (GRACE) satellite data were used to estimate the regional glacier mass variation over the Karakoram and Himalayas (KH) region during 2002–2019 hydrological years. Our study showed that the total mass change rate over the KH region was – 55.0 ± 8.7 Gt yr^–1 for the study period. We have identified four positive/negative clusters of mass change over the KH region, with the eastern part of the Karakoram (KK) and part of the Central Himalaya (CH) regions have experienced a positive mass change. In contrast, the junctio n area between the Western Himalaya (WH) and CH region observed an extreme negative mass change. The results demonstrated that the annual mass change for WH become negative or nearly zero from 2007/08 onwards, while for CH and Eastern Himalaya (EH) regions, it became negative since 2005/06. The GRACE-derived mass change was validated with the published in-situ mass balance data, which reveals a high correlation (r = 0.77) over the region. The performance of obtained results were also compared with Ice, Cloud, and Land Elevation Satellite-1 (ICESat-1) data for the period 2003–2009, indicating a correlation of 0.87 and 0.91 for monthly and annual scale, respectively. Moreover, the interannual mass change in the glaciated region was analyzed using hydro-climatic data and energy fluxes, suggesting a higher correlation of mass change with total precipitation and snowfall over the spatiotemporal scale. However, this correlation fails at locations where evaporation, runoff, and radiation have prominently influenced the mass loss. The uncertainty and sensitivity test for mass change demonstrated that snowfall and temperature have a strong influence on the response of mass change. Overall, this study provided regional mass change and their relationship with hydro-climatic variables, which will provide a better understanding related to the water availability in the downstream areas.

Information about the surface ice velocity is one of the important parameters for Mass balance and Glacier dynamics. This study estimates the surface ice velocity of Chhota Shigri glacier using Landsat (TM/ETM+) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) temporal data-sets from a period of 2009 to 2016 and 2006 to 2007, respectively. A correlation based Particle Image Velocimetry (PIV) technique has been used for the estimation of surface ice velocity. This technique uses multiple window sizes in the same data-set. Four window sizes (low, medium, high, very high) are used for each image pair. Estimated results have been compared with the published data. The outcomes attained from the medium window size closely matches with the published results. The estimated mean surface ice velocities of medium window size are 24 and 28.5 myr⁻¹ for 2009/2010 and 2006/2007 images pair. Highest velocity is observed in middle part of the glacier while lowest in the accumulation zone of the glacier.

Glacier change monitoring provides a significant understanding of glacier health and its influence on freshwater availability. Therefore, we have utilized remotely sensed data to estimate the glacier characteristics, mass balance, and volume change during 2013–2019 over the Sutri Dhaka and Batal glaciers, Chandra basin, western Himalayas. The glacier feature classification and shifting in isoline were mapped on a spatio-temporal scale. Furthermore, the surface velocity was measured using Coregistration of Optically Sensed Images and Correlation (COSI-Corr) and then used for estimating the ice thickness. The estimated velocity was compared with the stake observations and National Aeronautics and Space Administration (NASA)- Inter-Mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE) data. Further, the glaciers’ geodetic mass balance and volume change were calculated, indicating an average value of −0.03 ± 0.5, −0.34 ± 0.40 and −0.13 ± 0.14 m water equivalent (w.e.) year⁻¹ during 2000–2009, 2009–2020, and 2000–2020, respectively. This multidimensional analysis of the glaciers is critical, as the meltwater from both glaciers contributes to the Chandra basin and also influences the local ecosystem.