Quantifying the light absorption and source attribution of insoluble light-absorbing particles on Tibetan Plateau glaciers between 2013 and 2015

Wang, Xin; Wang, Hong; Liu, Jun; Xu, Bin; Wang, Mo; Ji, Mingxia; Jin, Hongchun

doi:10.5194/tc-13-309-2019

Cited by 20 publications

(12 citation statements)

References 92 publications

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“…The presence of other LAP types in the snowpack uncaptured by our chemical measurements might explain a part of the bias between optically retrieved and chemically 20 measured LAP concentrations observed in this study. For instance, Organic Carbon (OC) may play an important role in snowpack absorption (Lin et al, 2014;Wang et al, 2019). However, the peak absorption of OC is located between 350 and 400 nm and the impact at wavelengths higher than 400 nm is expected to be limited (Chen and Baker, 2010).…”

Section: Presence Of Other Lapsmentioning

confidence: 99%

Influence of light absorbing particles on snow spectral irradiance profiles

Tuzet¹,

Dumont²,

Arnaud³

et al. 2019

Preprint

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Light Absorbing Particles (LAP) such as black carbon or mineral dust are some of the main drivers of snow radiative transfer.Small amounts of LAP significantly increase snowpack absorption in the visible wavelengths where ice absorption is particularly weak, impacting the surface energy budget of snow-covered areas. However, linking measurements of LAP concentration in 5 snow to their actual radiative impact is a challenging issue which is not fully resolved. In the present paper, we point out a new method based on Spectral Irradiance Profile (SIP) measurements which makes it possible to identify the radiative impact of LAP on visible light extinction in homogeneous layers of the snowpack. From this impact on light extinction it is possible to infer LAP concentrations present in each layer using radiative transfer theory. This study relies on a unique dataset composed of 26 spectral irradiance profile measurements in the wavelength range 350-950 nm with concomitant profile measurements of snow 10 physical properties and LAP concentrations, collected in the Alps over two snow seasons in winter and spring conditions. For 55 homogeneous snow layers identified in our dataset, the concentrations retrieved from SIP measurements are compared to chemical measurements of LAP concentrations. A good correlation is observed for measured concentrations higher than 5 ng g −1 (r 2 = 0.74 ) despite a clear positive bias. The potential causes of this bias are discussed, underlining a strong dependence of our method to LAP optical properties and to the relationship between snow microstructure and snow optical properties used in 15 the theory. Additional uncertainties such as artefacts in the measurement technique for SIP and chemical contents along with LAP absorption efficiency, may explain part of this bias. In addition, spectral information on LAP absorption can be retrieved from SIP measurements. We show that for layers containing a unique absorber, this absorber can be identified in some cases (e.g: mineral dust vs black carbon). We also observe an enhancement of light absorption between 350 and 650 nm in presence of liquid water in the snowpack which is discussed but not fully elucidated. A single SIP acquisition lasts approximately one 20 minute and is hence much faster than collecting a profile of chemical measurements. With the recent advances in modelling LAP-snow interactions, our method could become an attractive alternative to estimate vertical profiles of LAP concentrations in snow.

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Section: Presence Of Other Lapsmentioning

confidence: 99%

Influence of light absorbing particles on snow spectral irradiance profiles

Tuzet¹,

Dumont²,

Arnaud³

et al. 2019

Preprint

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“…However, snow surface darkening due to light-absorbing particles (LAPs) such as black carbon (BC), organic carbon (OC), dust, and algae can significantly alter the reflective properties of snow (Warren, 1982(Warren, , 1984Hadley and Kirchstetter, 2012). When deposited on the snow surface, LAPs increase the absorption of solar radiation (Painter et al, 2012a;Liou et al, 2014;Wang et al, , 2019Dang et al, 2017), thereby reducing the snow albedo (Warren and Brandt, 2008;Kaspari et al, 2014). As a result, radiative forcing of LAPs in snow (RFLS) plays a critical role in snow-cover decline on both regional and global scales (Wiscombe and Warren, 1980), perturbing the climate system and impacting hydrological cycles (Barnett et al, 2005;Qian et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Satellite-based radiative forcing by light-absorbing particles in snow across the Northern Hemisphere

et al. 2021

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Abstract. Snow is the most reflective natural surface on Earth and consequently plays an important role in Earth's climate. Light-absorbing particles (LAPs) deposited on the snow surface can effectively decrease snow albedo, resulting in positive radiative forcing. In this study, we used remote-sensing data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and the Snow, Ice, and Aerosol Radiative (SNICAR) model to quantify the reduction in snow albedo due to LAPs before validating and correcting the data against in situ observations. We then incorporated these corrected albedo-reduction data in the Santa Barbara DISORT (Discrete Ordinate Radiative Transfer) Atmospheric Radiative Transfer (SBDART) model to estimate Northern Hemisphere radiative forcing except for midlatitude mountains in December–May for the period 2003–2018. Our analysis reveals an average corrected reduction in snow albedo (ΔαMODIS,correctedLAPs) of ∼ 0.021 under all-sky conditions, with daily radiative forcing (RFMODIS,dailyLAPs) values of ∼ 2.9 W m−2, over land areas with complete or near-complete snow cover and with little or no vegetation above the snow in the Northern Hemisphere. We also observed significant spatial variations in ΔαMODIS,correctedLAPs and RFMODIS,dailyLAPs, with the lowest respective values (∼ 0.016 and ∼ 2.6 W m−2) occurring in the Arctic and the highest (∼ 0.11 and ∼ 12 W m−2) in northeastern China. From MODIS retrievals, we determined that the LAP content of snow accounts for 84 % and 70 % of the spatial variability in albedo reduction and radiative forcing, respectively. We also compared retrieved radiative forcing values with those of earlier studies, including local-scale observations, remote-sensing retrievals, and model-based estimates. Ultimately, estimates of radiative forcing based on satellite-retrieved data are shown to represent true conditions on both regional and global scales.

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“…Snow is a highly reflective medium in the wavelengths of the visible and of the near infrared (up to 1.4 µm, referred to as NIR) where most of the solar energy is available (Warren, 1982). The amount of solar energy absorbed by snow-covered areas is hence small compared to other surfaces such as bare soil, vegetation or oceans, making snow a singular component of our climate system (Armstrong and Brun, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Wiscombe and Warren, 1980;Hadley and Kirchstetter, 2012;Skiles, 2014;Adolph et al, 2017). Nowadays the underlying theory is well known (Warren, 1982), and many radiative transfer models are able to numerically compute snow optical properties for given physical properties and LAP concentrations (e.g. Flanner and Zender, 2006;Aoki et al, 2011;Tuzet et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Influence of light-absorbing particles on snow spectral irradiance profiles

et al. 2019

View full text Add to dashboard Cite

Abstract. Light-absorbing particles (LAPs) such as black carbon or mineral dust are some of the main drivers of snow radiative transfer. Small amounts of LAPs significantly increase snowpack absorption in the visible wavelengths where ice absorption is particularly weak, impacting the surface energy budget of snow-covered areas. However, linking measurements of LAP concentration in snow to their actual radiative impact is a challenging issue which is not fully resolved. In the present paper, we point out a new method based on spectral irradiance profile (SIP) measurements which makes it possible to identify the radiative impact of LAPs on visible light extinction in homogeneous layers of the snowpack. From this impact on light extinction it is possible to infer LAP concentrations present in each layer using radiative transfer theory. This study relies on a unique dataset composed of 26 spectral irradiance profile measurements in the wavelength range 350–950 nm with concomitant profile measurements of snow physical properties and LAP concentrations, collected in the Alps over two snow seasons in winter and spring conditions. For 55 homogeneous snow layers identified in our dataset, the concentrations retrieved from SIP measurements are compared to chemical measurements of LAP concentrations. A good correlation is observed for measured concentrations higher than 5 ng g−1 (r2=0.81) despite a clear positive bias. The potential causes of this bias are discussed, underlining a strong sensitivity of our method to LAP optical properties and to the relationship between snow microstructure and snow optical properties used in the theory. Additional uncertainties such as artefacts in the measurement technique for SIP and chemical contents along with LAP absorption efficiency may explain part of this bias. In addition, spectral information on LAP absorption can be retrieved from SIP measurements. We show that for layers containing a unique absorber, this absorber can be identified in some cases (e.g. mineral dust vs. black carbon). We also observe an enhancement of light absorption between 350 and 650 nm in the presence of liquid water in the snowpack, which is discussed but not fully elucidated. A single SIP acquisition lasts approximately 1 min and is hence much faster than collecting a profile of chemical measurements. With the recent advances in modelling LAP–snow interactions, our method could become an attractive alternative to estimate vertical profiles of LAP concentrations in snow.

show abstract

Quantifying the light absorption and source attribution of insoluble light-absorbing particles on Tibetan Plateau glaciers between 2013 and 2015

Cited by 20 publications

References 92 publications

Influence of light absorbing particles on snow spectral irradiance profiles

Influence of light absorbing particles on snow spectral irradiance profiles

Satellite-based radiative forcing by light-absorbing particles in snow across the Northern Hemisphere

Influence of light-absorbing particles on snow spectral irradiance profiles

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