HR: 1330h
AN: GC12A-0151    [PDF]
TI: Transient Climate Change over California at a Regional Scale
AU: * Snyder, M A
EM: msnyder@es.ucsc.edu
AF: Climate Change and Impacts Laboratory, Dept. of Earth Sciences, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Sloan, L C
EM: lcsloan@es.ucsc.edu
AF: Climate Change and Impacts Laboratory, Dept. of Earth Sciences, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AB: Steady-state experiments of future climate change using regional climate models (RCM) have shown increased temperature, decreased snow accumulation and changes in precipitation over California under doubled preindustrial CO$_{2}$ concentrations. The forcing of these early experiments was done using global climate model (GCM) data with fixed sea surface temperatures (SST) and fixed CO$_{2}$ concentrations. Since SSTs were fixed, important feedbacks from the ocean to the atmosphere were not included in these experiments. Also, the CO2 concentrations are set to a single value throughout the experiments, and did not evolve as a function of time. To address these issues, we have taken global climate model output from a fully coupled ocean-atmosphere GCM, the NCAR CCSM1, for the time periods 1980-1999 and 2080-2099 and used that output to drive a RCM with a domain centered over California. The CO$_{2}$ concentrations in these experiments increase as function of time and thus are a more realistic representation of actual changes. CO$_{2}$ values for the future time period (2080-2090) are based on projections by the Intergovernmental Panel on Climate Change. Initial results from these experiments show increased temperatures by up to 5$\deg$ C on a monthly basis. Snow accumulation is decreased dramatically by over 220 mm snow water equivalent in the Sierra Nevada Mountains. Our results show precipitation increases over the northern half of the state in January and February and decreases in the same region in December. Precipitation also decreases over the Sierra Nevada Mountains in March and May.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1610 Atmosphere (0315, 0325)
DE: 3309 Climatology (1620)
DE: 3337 Numerical modeling and data assimilation
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting