Light-absorbing impurities in snow cover across Northern Xinjiang, China

Abstract

Light-absorbing impurities (LAIs, e.g. black carbon (BC), organic carbon (OC), mineral dust (MD)) deposited on snow cover reduce albedo and accelerate its melting. Northern Xinjiang (NX) is an arid and semi-arid inland region, where snowmelt leads to frequent floods that have been a serious threat to local ecological security. There is still a lack of quantitative assessments of the effects of LAIs on snowmelt in the region. This study investigates spatial variations of LAIs in snow and its effect on snow albedo, radiative forcing (RF) and snowmelt across NX. Results showed that concentrations of BC, OC (only water-insoluble OC), MD ranged from 32 to 8841 ng g−1, 77 to 8568 ng g−1 and 0.46 to 236 µg g−1, respectively. Weather Research and Forecasting Chemistry model suggested that residential emission was the largest source of BC. Snow, Ice, and Aerosol Radiative modelling showed that the average contribution of BC and MD to snow albedo reduction was 17 and 3%, respectively. RF caused by BC significantly exceeded RF caused by MD. In different scenarios, changes in snow cover duration (SCD) caused by BC and MD decreased by 1.36 ± 0.61 to 6.12 ± 3.38 d. Compared with MD, BC was the main dominant factor in reducing snow albedo and SCD across NX.

Shift in seasonal snowpack melt-out date due to light-absorbing particles at a high-altitude site in Central Himalaya

“…Our numerical estimates of the #SMLAP are broadly in the same range with those reported previously for the Himalaya (e.g. Ménégoz et al, 2014;Zhang et al, 2018;Zhong et al 2019). In addition, our method allows to estimate the LAP impact on the #SM in a more general form, given that the amount of precipitation and LAP mean deposition are known.…”

“…CC BY 4.0 License. the range of 1.4 ± 0.6 to 6.1 ± 3.4 days (Zhong et al, 2019). As a comparison, a different approach to estimate the reduced snow cover was presented by Ménégoz et al (2014).…”

APCC Data Report I: Black carbon and organic carbon dataset from atmosphere, glaciers, snow cover, precipitation, and lake sediment cores over the Third Pole

“…Snow cover samples were collected from 2 stations (Laohugou and Koktokay) (Fig. 1) and 138 snow survey sites in the TP and the Northern Xinjiang (Zhang et al, 2018a;Zhong et al, 2019Zhong et al, , 2021. Koktokay Snow Station at the headwater of the Irtysh River was selected as the fixed-point site, which is located in the Kayiertesi river basin, the first tributary of the Irtysh river.…”

“…Among them, 11 sampling sites were selected during the whole snow season, including sites located in the southern Altai Mountains, 3 sites on the west side of the Junggar Basin, and 3 sites in the northern Tianshan Mts. (Zhong et al, 2019).…”

“…Light absorbing BC and OC (including water soluble organic carbon (WSOC) and water insoluble organic carbon (WIOC)) deposited on the glacier and snow cover induced surface darkening and enhanced melting (Flanner et al, 2007;Kang et al, 2020;Lau and Kim, 2018;Santra et al, 2019;Xu et al, 2009;Zhang et al, 2020b). Estimates indicated that BC in snow resulted in accelerated glacier melt by approximately 15−20% in the southeast/central TP and Central Asia (Li et al, 2020;Zhang et al, , 2020b reduced snow cover duration by 3−4 days across the TP and 3−6 days in Northern Xinjiang (Zhang et al, 2018a;Zhong et al, 2019). Meanwhile, WSOC in snow may also contribute to glacier melting (Hu et al, 2018;, due to their light absorption equal to approximately 10% of that by BC in the northern TP and Northern Xinjiang (Yan et al, 2016;.…”