Effect of small-scale snow surface roughness on snow albedo and reflectance
: Manninen Terhikki, Anttila Kati, Jääskeläinen Emmihenna, Riihelä Aku, Peltoniemi Jouni, Räisänen Petri, Lahtinen Panu, Siljamo Niilo, Thölix Laura, Meinander Outi, Kontu Anna, Suokanerva Hanne, Pirazzini Roberta, Suomalainen Juha, Hakala Teemu, Kaasalainen Sanna, Kaartinen Harri, Kukko Antero, Hautecoeur Olivier, Roujean Jean-Louis
Publisher: COPERNICUS GESELLSCHAFT MBH
: 2021
Cryosphere
: CRYOSPHERE
: CRYOSPHERE
: 15
: 2
: 793
: 820
: 28
: 1994-0416
: 1994-0424
DOI: https://doi.org/10.5194/tc-15-793-2021
: https://tc.copernicus.org/articles/15/793/2021/
: https://research.utu.fi/converis/portal/detail/Publication/53693386
The primary goal of this paper is to present a model of snow surface albedo accounting for small-scale surface roughness effects. The model is based on photon recollision probability, and it can be combined with existing bulk volume albedo models, such as Two-streAm Radiative Trans-fEr in Snow (TARTES). The model is fed with in situ measurements of surface roughness from plate profile and laser scanner data, and it is evaluated by comparing the computed albedos with observations. It provides closer results to empirical values than volume-scattering-based albedo simulations alone. The impact of surface roughness on albedo increases with the progress of the melting season and is larger for larger solar zenith angles. In absolute terms, small-scale surface roughness can decrease the total albedo by up to about 0.1. As regards the bidirectional reflectance factor (BRF), it is found that surface roughness increases backward scattering especially for large solar zenith angle values.
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