Effect of small-scale snow surface roughness on snow albedo and reflectance

• Published in: The Cryosphere
• Main Authors: 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
• Other Authors: Centre d'études spatiales de la biosphère (CESBIO), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDE]Environmental Sciences; The Cryosphere
• Online Access: https://hal.science/hal-03388776; https://hal.science/hal-03388776/document; https://hal.science/hal-03388776/file/tc-15-793-2021.pdf; https://doi.org/10.5194/tc-15-793-2021

International audience 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 TransfEr 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.