Model Simulations of Orbital Sensitivity of North American Ice Sheets Pollard, D.; DeConto, R.M. Pollard, D. DeConto, R.M. earth science/paleoclimate/paleoclimatic modeling (latitude,null,null,degree north,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (upward ice sheet velocity,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,basal ice) earth science/paleoclimate/paleoclimatic modeling (ice sheet x velocity,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (ice sheet calving,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (ice sheet area,null,null,square meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (bedrock elevation,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (ice sheet elevation,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth 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modeling,null,null,N,grounded ice area) earth science/paleoclimate/paleoclimatic modeling (rainfall,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (ice sheet y velocity,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (notes,null,null,dimensionless,annual,paleoclimatic modeling,null,null,N,OH basin sector number) earth science/paleoclimate/paleoclimatic modeling (sea level,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (ice sheet thickness,null,null,meter,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (ice temperature,null,null,degree Celsius,annual,paleoclimatic modeling,null,null,N,surface temperature) earth science/paleoclimate/paleoclimatic modeling (ice temperature,null,null,degree Celsius,annual,paleoclimatic modeling,null,null,N,basal temperature) earth science/paleoclimate/paleoclimatic modeling (ice sheet y velocity,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,surface ice) earth science/paleoclimate/paleoclimatic modeling (snowfall,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (bedrock elevation,null,null,meter,annual,paleoclimatic modeling,null,null,N,equilibrium bedrock elevation) earth science/paleoclimate/paleoclimatic modeling (ice sheet melt,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,sub-ice oceanic melt rate) earth science/paleoclimate/paleoclimatic modeling (surface type,null,null,dimensionless,annual,paleoclimatic modeling,null,null,N,mask) earth science/paleoclimate/paleoclimatic modeling (ice sheet melt,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,face melt rate) earth science/paleoclimate/paleoclimatic modeling (upward ice sheet velocity,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,surface ice) earth science/paleoclimate/paleoclimatic modeling (longitude,null,null,degree east,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (ice sheet volume,null,null,cubic meter,annual,paleoclimatic modeling,null,null,N,grounded ice volume) earth science/paleoclimate/paleoclimatic modeling (ice sheet volume,null,null,cubic meter,annual,paleoclimatic modeling,null,null,N,floating ice volume) earth science/paleoclimate/paleoclimatic modeling (ice temperature,null,null,degree Celsius,annual,paleoclimatic modeling,null,null,N,basal homologous temperature) earth science/paleoclimate/paleoclimatic modeling (ice sheet x velocity,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,basal ice) earth science/paleoclimate/paleoclimatic modeling (ice sheet y velocity,null,null,meter per year,annual,paleoclimatic modeling,null,null,N,basal ice) earth science/paleoclimate/model (Global>LATITUDE >LONGITUDE ) The formulation of a 3-D ice sheet-shelf model is described. The model is designed for long-term continental-scale applications, and has been used mostly in paleoclimatic studies. It uses a hybrid combination of the scaled shallow ice and shallow shelf approximations for ice flow. Floating ice shelves and grounding-line migration are included, with parameterized ice fluxes at grounding lines that allows relatively coarse resolutions to be used. All significant components and parameterizations of the model are described in some detail. Basic results for modern Antarctica are compared with observations, and simulations over the last 5 million years are compared with previously published results. The sensitivity of ice volumes during the last deglaciation to basal sliding coefficients is discussed. STUDY NOTES: Snapshots of a 3-D ice sheet model (Pollard and DeConto, 2012) applied over North America and Greenland, driven either by simply parameterized climate (similarly to Pollard and DeConto, 2009), or by a look-up table of previous Global Climate Model (GCM) solutions (similarly to DeConto and Pollard, 2003), with idealized 40,000-yr sinusoidal climate variations. Main model variables of interest are: h = ice sheet thickness (m) hs = surface elevation (m) hb = bedrock elevation (m) maskwater = 0 for land or grounded ice, 1 for ocean or floating ice. Latitudes of grid points: Every 0.5 degrees, from 20.5 N to 84.5 N (130 points). Longitudes of grid points: Every 1.0 degrees, from 179.5 W to -10.5 W (170 points). Time period: Model integrations of up to 200,000 years, representing idealized orbital forcing with 40,000 year periodicity. Variables are saved every 2000 years, from 0 up to 200000 yr (up to 101 saves). Each NetCDF file contains results for one model experiment, named as follows: fort.92_cyca to fort.92_cych.nc: Using parameterized climate forcing, each with slightly different climate parameters. fort.92_gcmcyc1.nc to fort.92_gcmcyc5.nc: Using GCM lookup-table forcing, each with slightly different look-up parameters, mainly albedo feedback strength. ADDITIONAL REFERENCE: DeConto, R.M. and D. Pollard. 2003. Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2. Nature, 421, 245-249. ADDITIONAL REFERENCE: Pollard, D. and R.M. DeConto. 2009. Modelling West Antarctic ice sheet growth and collapse through the past five million years. Nature, 458, 329-332 NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Pollard, D. Investigator : DeConto, R.M. 2012-10-24 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13440 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycj.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/pollard2012icesheets.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc1.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc2.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycb.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc5.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc4.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyca.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycc.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyce.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cych.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycf.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycg.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyci.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycd.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc3.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycj.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/pollard2012icesheets.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc1.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc2.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycb.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc5.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc4.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyca.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycc.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyce.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cych.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycf.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycg.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyci.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycd.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc3.nc English https://www.ncdc.noaa.gov/paleo/study/13440 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycj.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/pollard2012icesheets.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc1.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc2.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycb.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc5.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc4.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyca.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycc.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyce.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cych.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycf.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycg.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cyci.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_cycd.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/pollard2012/fort.92_gcmcyc3.nc Pollard, D. and R.M. DeConto. 2012. Description of a hybrid ice sheet-shelf model, and application to Antarctica. Geoscientific Model Development, 5, 1273-1295. DOI: 10.5194/gmd-5-1273-2012 START YEAR: 200000 cal yr BP * END YEAR: 0 cal yr BP -180 -90 180 90