Fewer clouds in the Mediterranean: consistency of observations and climate simulations.
Clouds play a major role in the climate system, but large uncertainties remain about their decadal variations. Here we report a widespread decrease in cloud cover since the 1970 s over the Mediterranean region, in particular during the 1970 s-1980 s, especially in the central and eastern areas and during springtime. Confidence in these findings is high due to the good agreement between the interannual variations of cloud cover provided by surface observations and several satellite-derived and reanalysis products, although some discrepancies exist in their trends. Climate model simulations of the historical experiment from the Coupled Model Intercomparison Project Phase 5 (CMIP5) also exhibit a decrease in cloud cover over the Mediterranean since the 1970 s, in agreement with surface observations, although the rate of decrease is slightly lower. The observed northward expansion of the Hadley cell is discussed as a possible cause of detected trends.
Instituto Pirenaico de Ecología, Consejo Superior de Investigaciones Científicas (IPE-CSIC), Zaragoza, Spain.
Arturo
A
Sanchez-Lorenzo
Department of Physics, University of Girona, Girona, Spain.
Aaron
A
Enriquez-Alonso
Department of Physics, University of Girona, Girona, Spain.
Josep
J
Calbó
Department of Physics, University of Girona, Girona, Spain.
Josep-Abel
JA
González
Institute for Atmospheric and Climate Sciences, ETH Zürich, Zürich, Switzerland.
Martin
M
Wild
Institute for Atmospheric and Climate Sciences, ETH Zürich, Zürich, Switzerland.
Doris
D
Folini
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA.
Joel R
JR
Norris
Instituto Pirenaico de Ecología, Consejo Superior de Investigaciones Científicas (IPE-CSIC), Zaragoza, Spain.
Sergio M
SM
Vicente-Serrano