Gulf Coast Analysis

From the links above you can access information about an analysis of output from several state-of-the-art Atmosphere-Ocean General Circulation Models (AOGCMs). These models have contributed results from their respective runs under a number of SRES scenarios (here we analyse A2 and B1) to an archive maintained at PCMDI in order to facilitate multi-model analyses for the 4th Assessment Report of the Intergovernmental Panel on Climate Change, due in 2007.

We have extracted average surface temperature and precipitation for a region covering the Gulf Coast (lat : 25 - 37 deg. North, lon: 108 -78 deg. West ). The fields have been area averaged (each gridpoint weighted by the cosine of its latitudinal coordinate), so that they are represented by one seasonal value for each variable+model+period. We show two series of separate results, one where we averaged only gridpoint over land, one where we averaged all the gridpoints within the rectangular region.

Our statistical model combines the different AOGCMs projections and delivers Probability Distribution Functions (PDFs) of temperature and precipitation change for a specific season (DJF or JJA) and scenario (A2 and B1). The two periods we consider in order to define "change" are here 1961-1990 and 2071-2100.

As part of the analysis we need observations for the current period, and we use NCEP/NCAR Reanalysis fields of temperature and precipitation, extracted and averaged over the same domains.

For more information on the method, please see http://www.assessment.ucar.edu/uncertainty_models/index.html under "Future Climate Change at Regional Scales". A paper is in press in Journal of Climate (Tebaldi et al. Quantifying Uncertainties in Projections of Regional Climate Change: a Bayesian Approach to the analysis of Multimodel Ensembles, to appear, May 2005), a simpler description of the model is contained in Tebaldi et al. "Regional Probabilities of Precipitation Change: A Bayesian Analysis of Multimodel Simulations". Geophysical Research Letters, vol. 31, 2004.