ANNOUNCEMENTS
The outputs from Community Atmospheric Model (CAM5) was used to study the seasonality and trend of Black carbon and Dust aerosol deposition over the glaciers and snow cover in the Himalayan – Karakoram region during the period 2005 – 2015. MERRA-2 reanalysis datasets were used to evaluate the simulation of BC and Dust aerosols and the snow characteristics of the study area. Similar to the reanalysis data, the simulated BC depositions over the snow cover also shows that the maximum deposition occurs during the monsoon and two minimum during pre-monsoon and post-monsoon. There is also a significant deposition during winter as well. It is also concluded that the Mass of BC over the snow peaks during the pre-monsoon season and lowers during the monsoon. Dust deposition over the H-K region also peaks during the summer. Simulated result captured a decrease in dry deposition during pre-monsoon, but nor MERRA-2. High Spatial variability and vertical distributions make the comparison of BC and Dust depositions of modelled data with the reanalysis data more complex. Dust concentrations in the snow surface and snow column also peaks during pre-monsoon and decreases during summer. It is also understood from this study that both dry and wet deposition affect the glaciers. Reanalysis dust deposition over the snow cover varies by one to two orders magnitude than those simulated by CAM5. Overall, CAM5 performed reasonably well with the reanalysis datasets. This study found that both dry and wet depositions of BC and Dust aerosols over the snow cover in the H-K region is showing positive trend and explicitly affecting the snow cover of the region. Single Scattering Albedo from the CAM5 simulation shows that the deposited aerosols in the region are of absorbing type and 2 meter air temperature also exhibits positive trend. Both these results show that the aerosol deposition affects the snow pack negatively and leads to a reduction in surface albedo and enhances the melting of glaciers and snow cover. Simulations from the Community Land Model (CLM) also validates this by showing the increased snow melt and runoff. It is also concluded that the dust deposition is more as compared to the BC. Pearson Correlation test and ANOVA was performed to study the relation between the deposited BC and the snow melt in the H-K region and results show that the aerosol deposition strongly influence snow melt and are highly correlated.
Keywords: Light Absorbing Aerosols, Glaciers, Atmospheric Model, Land Model, Seasonality, Summer Monsoon
