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

Xinyue Zhong,Wei Zhang,Pengfei Chen,Yulan Zhang,Shichang Kang,Xiaofei Li,Yajun Liu,Junhua Yang

doi:10.1017/jog.2019.69

Abstract

AbstractLight-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−1and 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.

Highlights

Black carbon (BC), organic carbon (OC) and mineral dust (MD) are the three primary components of light-absorbing impurities (LAIs) in snow and ice
LAIs remained on the snow surface because of their insolubility and large particles, or local soil was lifted which led to more deposited aerosols in snow (Bond and others, 2013; Doherty and others, 2016)
Surface snow samples collected from 106 sites were used to investigate spatial variations in LAIs across Northern Xinjiang (NX) from 2015 to 2017

Summary

Introduction

Black carbon (BC), organic carbon (OC) and mineral dust (MD) are the three primary components of light-absorbing impurities (LAIs) in snow and ice. Research on LAIs in snow cover at mid-latitudes were mainly concentrated in North America (Grenfell and others, 1981; Chýlek and others, 1999; Qian and others, 2009, 2015; Doherty and others, 2014, 2016; Kaspari and others, 2015), Europe (Sergent and others, 1993, 1998; Painter and others, 2013; Di Mauro and others, 2015; Gabbi and others, 2015), high mountain regions of Asia, including the Tibetan Plateau (TP) and the Hindu-Kush Himalaya (Xu and others, 2006; Ming and others, 2009; Ménégoz and others, 2014; Qu and others, 2014; Li and others, 2017; Zhang and others, 2018), and northern China (Huang and others, 2011; Ye and others, 2012; Wang and others, 2013; Pu and others, 2017). Their results indicated that the closer to the human activity centres a location is, the higher the LAI concentration is

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