HR: 17:45h
AN: GC24A-07    [Abstracts]
TI: Detection and Attribution of Human Influence on Climate at Sub-regional Scale: the Case of France
AU: * Terray, L
EM: terray@cerfacs.fr
AF: CERFACS, 42, Avenue Gaspard Coriolis, Toulouse cedex 1, 31057, France
AU: Planton, S
EM: planton@meteo.fr
AF: CNRM/Meteo-France, 42, Avenue Gaspard Coriolis, Toulouse cedex 1, 31057, France
AB: Human influence - mainly greenhouse gases and tropospheric sulphate aerosols -on climate has been detected on a wide range of climate variables such as surface air temperature, precipitation and sea level pressure. Global-scale detection and attribution studies have been extended to continental-scale for regions varying in size from a few to several thousand kilometres, using similar models as those used in global analyses. Here we use a specific regional framework to assess the extent to which human-induced changes in greenhouse gases and sulphate aerosols may be detected and attributed down to spatial scales of a few hundred kilometres. Using a high-quality dataset of observed temperature and large ensembles of high- resolution atmospheric model simulations, we detect a significant human influence on the 20th century evolution of summer night and day time temperature over France. The origin of the spatial warming pattern can be traced back to the spatial distribution of soil moisture climatology and a higher sensitivity of evapotranspiration to soil moisture changes in dry areas. These findings emphasize the importance of soil moisture-temperature feedbacks in influencing the future summer climate change in France and Western Europe. Our regional analysis also suggests that the France accelerated warming of the 20th century last decades is mainly due to human influence with an additional contribution from natural oceanic forcing associated to Atlantic multidecadal variability.
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1637 Regional climate change
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting