Greenland Basal Heat Flux
A NetCDF file containing updated basal heat flux data for Greenland projected and interpolated onto the standard 5km grid can be downloaded by clicking here. Metadata in the file describes its contents and is also given in the table below. More information on the technique can be obtained by contacting Michael Purucker (michael.e.purucker -at- nasa.gov). An archive including the python scripts to create: (1) the NetCDF file, (2) the table of metadata, and (3) the figure at the bottom of this page, along with the data files used by these scripts is available by clicking here.
| GLOBAL ATTRIBUTES | |
| title | Greenland basal heat flux |
| creator_name | Glen Granzow |
| institution | University of Montana |
| date_created | October 1, 2012 |
| summary | This data set contains basal heat flux data for Greenland based on satellite magnetic field measurements. The data has been projected and interpolated onto the standard CISM grid. |
| mapping | |
| ellipsoid | WGS84 |
| grid_mapping_name | polar_stereographic |
| latitude_of_projection_origin | [ 90.] |
| standard_parallel | [ 71.] |
| straight_vertical_longitude_from_pole | [-39.] |
| false_easting | [ 0.] |
| false_northing | [ 0.] |
| bheatflx | |
| long_name | Basal Heat Flux |
| standard_name | upward_geothermal_flux_at_ice_base |
| units | watts/meter^2 |
| grid_mapping | mapping |
| creator_name | Glen Granzow |
| contributor_name | Michael Purucker |
| contributor_role | Michael Purucker provided the original data from which this data set was interpolated. |
| contributor_url | http://core2.gsfc.nasa.gov/research/purucker/heatflux_updates.html |
| reference_url | http://core2.gsfc.nasa.gov/research/purucker/foxmaule_dkc09-09_greenland.pdf |
| source | http://core2.gsfc.nasa.gov/research/purucker/heatflux_mf7_foxmaule05.txt |
| reference | Fox Maule, C., Purucker, M.E., Olsen, N. & Mosegaard, K., 2005. Heat flux in Antarctica revealed from satellite magnetic data, Science, 309, 464-467, doi: 10.1126/science.1106888. |
| comments | The original data, provided by Mike Purucker, giving the basal heat flux at specific longitudes and latitudes is quite sparse. Projection and interpolation of the data onto the CISM standard grid was accomplished using a python script written by Glen Granzow. This script used pyproj, a python interface to the PROJ.4 library, to generate x,y coordinates in the required stereographic projection then matplotlib.mlab.griddata for interpolation. matplotlib.mlab.griddata implements natural neighbor interpolation which is based on Delaunay triangulation. To interpolate onto grid points outside the convex hull of the original data set, four fictitious points were added to the original data, one outside each corner of the final data grid. The assumed value of heat flux at the fictitious points was the mean of the heat flux at the actual data points. The vast majority of the interpolated data influenced by these fictitious points are in the ocean and thus of little concern. |
| x1 | |
| long_name | Cartesian x-coordinate |
| standard_name | projection_x_coordinate |
| units | meters |
| y1 | |
| long_name | Cartesian y-coordinate |
| standard_name | projection_y_coordinate |
| units | meters |
| time | |
| calender | none |
| long_name | Time |
| standard_name | time |
| units | year since 1-1-1 0:0:0 |
The crosses "+" in the above figure represent the location of the data points which were interpolated to create the Greenland_heat_flux_5km.nc data file. The four points just outside the four corners of the final grid were not in the original data but were created to allow interpolation outside the convex hull of the original data. The assumed value of heat flux at these "fictitious" points was the mean of the heat flux at the actual data points. The vast majority of the interpolated data influenced by these fictitious points are in the ocean and thus of little concern.
