HR: 1340h
AN: GC43A-0942    [Abstracts]
TI: Skill-Change Relations and Inter-Model Scatter in CMIP3 Surface Field Projections
AU: * Scherrer, S C
EM: scherrer@ucar.edu
AF: Climate and Global Dynamics Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307, United States
AU: Baettig, M B
EM: baettig@gmx.ch
AF: Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, Universitätstrasse 16, Zürich, CH-8092, Switzerland
AB: CMIP3 projections of future climate change agree fairly well on global changes of mean surface temperature (T) and precipitation (P), but there are still considerable differences on regional scales. An interesting question is whether these uncertainties can be somehow constrained. Although the global multi-model mean skill for T and P is higher than the skill of the best model we show that there are indeed some robust relations between simple global skill measures of the present-day representation of T and the projected changes in T especially in the tropics and near the poles. Local skill-change relations on the other hand reveal mainly model biases (e.g. caused by excessive snow pack in spring). While these are useful for identifying model deficiencies and stimulating model developments, they are not necessarily useful for constraining uncertainties in future changes. The amplitude and inter-model scatter (IMS) of projected late 21st century changes in T and P extremes is analyzed using the recently introduced Climate Change Index (CCI). The IMS expressed as the inter-model standard deviation varies between 0.37 for the western subtropical Pacific and 4.69 in the northern Atlantic deep water formation region (a factor of 12.8). It is generally smallest in the subtropics where the CCI shows average values. Large IMS is found in the ENSO region, Amazon basin and the polar regions. In the former two regions, the scatter is mainly related to differences in the changes of P extremes. For the polar regions, the large scatter is caused by different changes in temperature and precipitation extremes. This seems mainly related to model- dependent differences in sea ice, snow and possibly cloud changes.
DE: 1626 Global climate models (3337, 4928)
DE: 1699 General or miscellaneous
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
DE: 3354 Precipitation (1854)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting