Difference between revisions of "Future Climate Data"
(→Future Climate Forcing Processed Data)
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==Future Climate Raw Data==
==Future Climate Raw Data==
data from 18 of the AR4 models .
Most of these data sets cover the period from Jan 2004 through Dec 2098.
Latest revision as of 15:19, 3 February 2014
Future Climate Raw Data
The future climate data comes from 18 of the AR4 models that participated in the A1B scenario. (Thanks to Tom Bracegirdle at BAS for the data.) Most of these data sets cover the period from Jan 2004 through Dec 2098.
Fields we have:
- orography Media:orog.nc
- 2m air temperature Media:tas.tar.gz
- total precipitation Media:pr.tar.gz
- near surface specific humidity Media:huss.tar.gz
- 3-D fields of air temperature on pressure levels, the gz file contains nested tar files for each pressure level Media:3dtemp.tar.gz
Future Climate Forcing Processed Data
The global monthly precipitation, monthly two-meter air temperature, and orography fields have been consolidated into the single NetCDF file below. The data has been extrapolated to the poles and the precipitation converted to meters/year of water equivalent (instead of (kg/square meter)/second as in the files above).
The data in this file has been used along with the present day data file to create a future climate file for Greenland on the "standard" 5km grid providing annual mean temperatures, July mean temperatures, precipitation, and ablation. Net accumulation can be obtained by subtracting ablation from precipitation. Future temperatures and precipitation were obtained by adding anomalies to the present day data. The anomalies were found by calculating differences in the global climate model data then interpolating onto the finer standard grid using bilinear interpolation. Using this method results in some grid points having (small) negative values for precipitation; such values were set to zero. Ablation was estimated using a Positive Degree Day (PDD) scheme with sigma = 4.5, wmax = 0.6, pddfac_snow = 0.003, and pddfac_ice = 0.008. For a description of the PDD scheme see  Reeh, N. (1991), "Parameterization of Melt Rate and Surface Temperature on the Greenland Ice Sheet"; Polarforschung 59/3: 113-128, 1989 (erschienen 1991) and/or  Rutt, I.C., M. Hagdorn, N.R.J. Hulton, and A.J. Payne (2009), "The Glimmer community ice sheet model"; Journal of Geophysical Research, Vol. 104, F02004, doi:10.1029/2008JF001015, 2009.
The data in the consolidated NetCDFfile has also been used along with the present day data file to create a future climate file for Antarctica on the "standard" 5km grid providing annual mean temperatures and precipitation. Future temperatures and precipitation were calculated as they were for the Greenland file above. That is, future temperatures and precipitation were obtained by adding anomalies to the present day data. The anomalies were found by calculating differences in the global climate model data then interpolating onto the finer standard grid using bilinear interpolation. Any resulting negative precipitation values were set to zero. Extrapolation to the south pole was done by assuming that the anomaly at the pole is the mean of the anomalies at 85 degrees south.