Radiation and hydrological cycle on global scales

Radiation and hydrological cycle on global scales: The focus of this activity is on the relation between the energy and water cycles on global to regional scales. Decadal variations in surface radiation, the key driver of the hydrological cycle, are extensively studied, using both climate models and observational data. A major issue is the detected decrease of surface solar radiation up to the 1980s  ("global dimming") and its partial recovery thereafter ("brightening"), as well as their consequences for climate change (Wild et al., 2005, Wild et al. 2008, Mercado et al. 2009). The outcome of these research activities is documented in a recent special issue on global dimming and brightening in the Journal of Geophysical Research, with group members involved in 10 related publications (4 of them selected as AGU highlights). Evidence for an intensification of the terrestrial hydrological cycle since the mid-1980s has been provided from both surface energy and water balance perspectives (Wild et al. 2008). Consistent estimates of decadal changes in surface radiation and precipitation suggest that the concurrent increase in both solar and greenhouse forcing at land surfaces has favoured the intensification of the hydrological cycle since the mid-1980s. In contrast, in prior decades, global dimming counteracted the greenhouse forcing and suppressed an acceleration of the hydrological cycle.

Related projects:

Global Energy Balance Archive (GEBA)

Modeling and diagnosing changes in radiation and surface energy balance

NCCR climate project (P2.1): Intensification of the water cycle: Scenarios, processes and extremes (HyClim)