Abstract
Light-absorbing impurities (LAIs) in surface snow and snow pits together with LAIs’ concentrations and their impacts on albedo reduction and sequent radiative forcing (RF) have been investigated in the past. Here, we focused on temporal–spatial distributions of LAIs, especially on the albedo reduction and radiative forcing caused by the LAIs in Urumqi Glacier No.1. Various snow samples, including fresh snow, aged snow, and granular ice were collected between 3,770 and 4,105 m a.s.l of Urumqi Glacier No.1 during the snowmelt season of 2015. For the surface snow samples, BC and OC concentrations were 582 and 1,590 ng g−1, respectively. Mineral dust (MD) concentrations were 110 μg g−1. Due to the different ablation status of the glacier surface, LAIs accumulate at the lower altitude of the glacier. The estimation by the Snow, Ice, and Aerosol Radiative (SNICAR) model indicated that BC and MD could reduce the albedo by 12.8 and 10.3% in fresh snow, aged snow by 23.3 and 5.9%, and granular ice by 22.4 and 26.7%, respectively. The RF of MD was higher than that of BC in fresh snow and granular ice, whereas the RF of BC exceeded MD in aged snow. These findings suggested that BC was the main forcing factor in snow melting and dust was the main forcing factor in accelerating glacier melt.
Highlights
Light-absorbing impurities (LAIs) play a vital role in melting snow and glaciers in High Asia (Ming et al, 2012; Qian et al, 2015) and across the globe (Warren and Wiscombe, 1980; Hansen and Nazarenko, 2004; Flanner et al, 2007; Painter et al, 2013)
black carbon (BC) played a vital role in the process of snow melting on Urumqi Glacier No
The radiative forcing (RF) of Mineral dust (MD) was higher than that of BC in fresh snow and granular ice, whereas the RF of BC exceeded MD in aged snow, which indicated that BC was the dominant factor in the melting of snow and MD caused higher RF when the glacier surface was without snow distribution
Summary
Light-absorbing impurities (LAIs) play a vital role in melting snow and glaciers in High Asia (Ming et al, 2012; Qian et al, 2015) and across the globe (Warren and Wiscombe, 1980; Hansen and Nazarenko, 2004; Flanner et al, 2007; Painter et al, 2013). LAIs include black carbon (BC), organic carbon (OC; in this study, only water-insoluble OC is considered), and mineral dust (MD). LAIs deposited on glacier surface via precipitation and dry deposition may accelerate. Glacier melting by absorbing solar radiation (Bond et al, 2013; Gabbi et al, 2015). It is critical to assess their contributions to glacier melting and get a picture of glacier runoff and water resources in glacierized catchments
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