Airborne Measurements of Surface Albedo and Leaf Area Index of Snow-Covered Boreal Forest

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Manninen, Terhikki, Roujean, Jean-Louis, Hautecoeur, Olivier, Riihelä, Aku, Lahtinen, Panu, Jääskeläinen, Emmihenna, Siljamo, Niilo, Anttila, Kati, Sukuvaara, Timo, Korhonen, Lauri
• 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), Météo-France
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: albedo; snow; boreal forest; airborne; leaf area index; satellite; [SDU]Sciences of the Universe [physics]; Paras; Subarctic; Lapland
• Online Access: https://insu.hal.science/insu-03668295; https://insu.hal.science/insu-03668295/document; https://insu.hal.science/insu-03668295/file/JGR%20Atmospheres%20-%202021%20-%20Manninen%20-%20Airborne%20Measurements%20of%20Surface%20Albedo%20and%20Leaf%20Area%20Index%20of%20Snow_E2_80_90Covered%20Boreal.pdf; https://doi.org/10.1029/2021JD035376

International audience Helicopter based simultaneous measurements of broadband surface albedo and the effective leaf area index (LAI eff ) were carried out in subarctic area of Finnish Lapland in spring 2008, 2009, and 2010 under varying illumination and snow cover conditions. Vertical profile measurements show that the found relationship between albedo and LAI eff seems to be rather independent of the flight altitude and therefore the footprint scale. Actually, flights above 500 m in altitude revealed low variations of the surface albedo approaching an aerial average at 1 km, meaning that a footprint of 20 km is representative of the landscape. The albedo of the area was beta distributed, and without LAI eff values below 0.25, the average albedo value of the area would decrease from 0.49 to 0.44 showing the albedo sensitivity to sparse vegetation. The results agreed with the photon recollision probability based model PARAS and the MODIS satellite albedo product MCD43A3. However, differences between satellite based and airborne albedo values were noticed, which could be explained by a difference in footprint size and/or the strong local heterogeneity as certain flights were operated on specific targets.