Parameterization of single-scattering properties of snow
Snow consists of non-spherical grains of various shapes and sizes. Still, in many radiative transfer applications, single-scattering properties of snow have been based on the assumption of spherical grains. More recently, second-generation Koch fractals have been employed. While they produce a relat...
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ftdoajarticles:oai:doaj.org/article:d97862af908241f89001bb4193e02d22 2023-05-15T17:48:28+02:00 Parameterization of single-scattering properties of snow P. Räisänen A. Kokhanovsky G. Guyot O. Jourdan T. Nousiainen 2015-06-01T00:00:00Z https://doi.org/10.5194/tc-9-1277-2015 https://doaj.org/article/d97862af908241f89001bb4193e02d22 EN eng Copernicus Publications http://www.the-cryosphere.net/9/1277/2015/tc-9-1277-2015.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-9-1277-2015 https://doaj.org/article/d97862af908241f89001bb4193e02d22 The Cryosphere, Vol 9, Iss 3, Pp 1277-1301 (2015) Environmental sciences GE1-350 Geology QE1-996.5 article 2015 ftdoajarticles https://doi.org/10.5194/tc-9-1277-2015 2022-12-30T21:33:26Z Snow consists of non-spherical grains of various shapes and sizes. Still, in many radiative transfer applications, single-scattering properties of snow have been based on the assumption of spherical grains. More recently, second-generation Koch fractals have been employed. While they produce a relatively flat phase function typical of deformed non-spherical particles, this is still a rather ad hoc choice. Here, angular scattering measurements for blowing snow conducted during the CLimate IMpacts of Short-Lived pollutants In the Polar region (CLIMSLIP) campaign at Ny Ålesund, Svalbard, are used to construct a reference phase function for snow. Based on this phase function, an optimized habit combination (OHC) consisting of severely rough (SR) droxtals, aggregates of SR plates and strongly distorted Koch fractals is selected. The single-scattering properties of snow are then computed for the OHC as a function of wavelength λ and snow grain volume-to-projected area equivalent radius r vp . Parameterization equations are developed for λ = 0.199–2.7 μm and r vp = 10–2000 μm, which express the single-scattering co-albedo β, the asymmetry parameter g and the phase function P 11 as functions of the size parameter and the real and imaginary parts of the refractive index. The parameterizations are analytic and simple to use in radiative transfer models. Compared to the reference values computed for the OHC, the accuracy of the parameterization is very high for β and g . This is also true for the phase function parameterization, except for strongly absorbing cases (β > 0.3). Finally, we consider snow albedo and reflected radiances for the suggested snow optics parameterization, making comparisons to spheres and distorted Koch fractals. Article in Journal/Newspaper Ny Ålesund Ny-Ålesund Svalbard The Cryosphere Directory of Open Access Journals: DOAJ Articles Ny-Ålesund Svalbard The Cryosphere 9 3 1277 1301 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 P. Räisänen A. Kokhanovsky G. Guyot O. Jourdan T. Nousiainen Parameterization of single-scattering properties of snow |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Snow consists of non-spherical grains of various shapes and sizes. Still, in many radiative transfer applications, single-scattering properties of snow have been based on the assumption of spherical grains. More recently, second-generation Koch fractals have been employed. While they produce a relatively flat phase function typical of deformed non-spherical particles, this is still a rather ad hoc choice. Here, angular scattering measurements for blowing snow conducted during the CLimate IMpacts of Short-Lived pollutants In the Polar region (CLIMSLIP) campaign at Ny Ålesund, Svalbard, are used to construct a reference phase function for snow. Based on this phase function, an optimized habit combination (OHC) consisting of severely rough (SR) droxtals, aggregates of SR plates and strongly distorted Koch fractals is selected. The single-scattering properties of snow are then computed for the OHC as a function of wavelength λ and snow grain volume-to-projected area equivalent radius r vp . Parameterization equations are developed for λ = 0.199–2.7 μm and r vp = 10–2000 μm, which express the single-scattering co-albedo β, the asymmetry parameter g and the phase function P 11 as functions of the size parameter and the real and imaginary parts of the refractive index. The parameterizations are analytic and simple to use in radiative transfer models. Compared to the reference values computed for the OHC, the accuracy of the parameterization is very high for β and g . This is also true for the phase function parameterization, except for strongly absorbing cases (β > 0.3). Finally, we consider snow albedo and reflected radiances for the suggested snow optics parameterization, making comparisons to spheres and distorted Koch fractals. |
format |
Article in Journal/Newspaper |
author |
P. Räisänen A. Kokhanovsky G. Guyot O. Jourdan T. Nousiainen |
author_facet |
P. Räisänen A. Kokhanovsky G. Guyot O. Jourdan T. Nousiainen |
author_sort |
P. Räisänen |
title |
Parameterization of single-scattering properties of snow |
title_short |
Parameterization of single-scattering properties of snow |
title_full |
Parameterization of single-scattering properties of snow |
title_fullStr |
Parameterization of single-scattering properties of snow |
title_full_unstemmed |
Parameterization of single-scattering properties of snow |
title_sort |
parameterization of single-scattering properties of snow |
publisher |
Copernicus Publications |
publishDate |
2015 |
url |
https://doi.org/10.5194/tc-9-1277-2015 https://doaj.org/article/d97862af908241f89001bb4193e02d22 |
geographic |
Ny-Ålesund Svalbard |
geographic_facet |
Ny-Ålesund Svalbard |
genre |
Ny Ålesund Ny-Ålesund Svalbard The Cryosphere |
genre_facet |
Ny Ålesund Ny-Ålesund Svalbard The Cryosphere |
op_source |
The Cryosphere, Vol 9, Iss 3, Pp 1277-1301 (2015) |
op_relation |
http://www.the-cryosphere.net/9/1277/2015/tc-9-1277-2015.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-9-1277-2015 https://doaj.org/article/d97862af908241f89001bb4193e02d22 |
op_doi |
https://doi.org/10.5194/tc-9-1277-2015 |
container_title |
The Cryosphere |
container_volume |
9 |
container_issue |
3 |
container_start_page |
1277 |
op_container_end_page |
1301 |
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