Observational evidence for cloud cover enhancement over western European forests

Adriaan J. Teuling (1) , Christopher M. Taylor (2, 3) , Jan Fokke Meirink (4) , Lieke A. Melsen (5) , Diego G. Miralles (6) , Chiel C. van Heerwaarden (7) , Robert Vautard (8, 9) , Annemiek I. Stegehuis (8) , Gert-Jan Nabuurs (10) , Jordi Vilà-Guerau de Arellano (7)

1 Hydrology and Quantitative Water Management Group
2 CEH - Centre for Ecology and Hydrology [Wallingford]
3 NCEO - NERC National Centre for Earth Observation
4 KNMI - Royal Netherlands Meteorological Institute
5 Hydrology and Quantitative Water Management Group,
6 Department of Earth Sciences [Amsterdam]
7 Meteorology and Air Quality Group
8 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
9 ESTIMR - Extrèmes : Statistiques, Impacts et Régionalisation
10 Wageningen Environmental Research (Alterra)

Forests impact regional hydrology and climate directly by regulating water and heat fluxes. Indirect effects through cloud formation and precipitation can be important in facilitating continental-scale moisture recycling but are poorly understood at regional scales. In particular, the impact of temperate forest on clouds is largely unknown. Here we provide observational evidence for a strong increase in cloud cover over large forest regions in western Europe based on analysis of 10 years of 15 min resolution data from geostationary satellites. In addition, we show that widespread windthrow by cyclone Klaus in the Landes forest led to a significant decrease in local cloud cover in subsequent years. Strong cloud development along the downwind edges of larger forest areas are consistent with a forest-breeze mesoscale circulation. Our results highlight the need to include impacts on cloud formation when evaluating the water and climate services of temperate forests, in particular around densely populated areas.

Domaines: Océan, Atmosphère; Interfaces continentales, environnement

Adriaan J. Teuling, Christopher M. Taylor, Jan Fokke Meirink, Lieke A. Melsen, Diego G. Miralles, et al.. Observational evidence for cloud cover enhancement over western European forests. Nature Communications, 2017, 8, pp.14065. ⟨10.1038/ncomms14065⟩. ⟨hal-01584257⟩