I worked as a project scientist for the U.S. National Assessment
of the potential consequences of climate variability and change.
I served as the climate scenarios coordinator for the National Assessment
Working Group and the National Assessment Coordination Office in Washington D
C. I was located with the Climate and Global Dynamics Division at the National Center for Atmospheric
Research in Boulder, Colorado. The simulations used in the U.S.
National Assessment all involve coupled atmosphere-ocean general circulation
models (GCMs) with transient greenhouse gases and sulfate aerosols. These
simulations include the CCCma CGCM1 (Canadian) model and the Hadley HADCM2 model
(British). Data from the MPI/DKRZ ECHAM4/OPYC3 (German) model, using similar emissions scenarios,
are also available. NCAR has completed several new simulations that
include a) multiple greenhouse gases b) more realistic sulfate emissions
scenario c) actual sulfate chemistry model and a d) coupled atmosphere-ocean GCM
that is not flux-corrected. The VEMAP project has downscaled the historical station data from
NOAA's National Climatic Data Center's U.S. Historical Climate Network ( HCN) and other cooperative network stations, plus USFS and BLM
SnoTel stations for high elevation precipitation to account for
elevational effects. The future GCM data is applied to this data set to
produce a downscaled version of the GCM output.
Emissions
Scenarios: These figures are the
equivalent CO2 concentrations and sulfate emissions that were used to force the
GCM simulations used in the U.S. National Assessment
.
Intermodel Comparisons: These figures are the global and U.S. temperature and precipitation trends for several GCMs using an approximately 1% increase in greenhouse gases plus sulfate aerosols.
Time Series: These figures are the minimum temperature, maximum temperature, and precipitation time series averaged over the U.S. for the HCN and VEMAP-processed data.
Maps: These figures are the temperature and precipitation trends observed over the 20th century and projected for the 21st century by the Canadian and Hadley models.