1. Université Clermont Auvergne, CNRS, GEOLAB, F-63000 Clermont-Ferrand, France
2. Luxembourg Institute of Science and Technology (LIST), Environmental Research and Innovation Department (ERIN), Observatory for Climate, Environment and Biodiversity (OCEB), 41 rue du Brill, 4422 Belvaux, Luxembourg
3. Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, UMR6533, 4 avenue Blaise Pascal TSA 60026, CS 60026, 63178 Aubière cedex, France