This directory contains a collection of Map Projection Parameters (.mpp) and Grid Parameter Definition (.gpd) files that are used with mapping and gridding software (the mapx library and its application programs) at NSIDC.
See Points, Pixels, Grids, and Cells - A Mapping and Gridding Primer for background on the software.
See mapx for the latest news and software distribution.
These files can be installed anywhere on your local system.
The mapx library and its application programs use the environment variable PATHMPP to search for .mpp/.gpd files. PATHMPP can contain a list of directories that will be searched in order. For example, if you have placed these files in a subdirectory called 'nsidc_maps' located within your home directory, and you have your own local .mpp files in /my/other/path/, then, in C shell, you should specify
setenv PATHMPP ~/nsidc_maps:/my/other/path
(N.B. For long-time users of the mapx library: PATHGPD is obsolete, all routines now search PATHMPP only.)
There are two types of mpp/gpd files. Files in the top nsidc_maps directory are supported files. Supported files describe data sets that NSIDC distributes, and enjoy a higher level of support than the others. Unsupported files (in the subdirectory called "unsupported") are used for miscellaneous (possibly research only) data sets, and may be promoted to the supported level in the event that they are used for a distributed data set. Unsupported files also include files that we have written for data we may have used at one time or another, for example, the ncep.gpd files, and think that they might be useful to someone else who wants to use the mapx library and applications to do something similar.
If you wish to use the unsupported .mpp/.gpd files, remember to add the nsidc_maps/unsupported subdirectory to the list of directories in your PATHMPP.
This collection of mpp/gpd files has accumulated over a number of years and various projects at NSIDC, and unfortunately suffers from a lack of naming convention.
EASE2_Xyykm.gpd - Families of EASE-Grid-2.0 definitions, which use the WGS84 ellipsoid instead of the spherical Earth model used in the original EASE-Grids. These grid definitions make file distribution to/from geotiff format and GIS tools much easier than the original definitions. For these grids: X : N = Northern Lambert Azimuthal Equal-Area S = Southern Lambert Azimuthal Equal-Area M = Cylindrical Equal-Area and yy : grid resolution, in km (can include optional decimal point, e.g. '12.5' The 25/12.5/6.25 km grids are nested (exactly 4 of each 12.5-kilometer cells in each 25-kilometer cell, etc) The SMAP (Soil Moisture Active-Passive) grids (36/9/3/1 km) are nested (exact multiples of each successively finer resolution grid cells in each coarser resolution grid). Grn250m.gpd - DataRods 250 m Greenland subset of 25 km Northern Hemisphere EASE-Grid M200correct.mpp - 200 km scale Global Cylindrical EASE-Grid mpp. All supported EASE-Grid global gpds must refer to this mpp Ml.gpd - 25 km Global Cylindrical EASE-Grid Mh.gpd - 12.5 km Global Cylindrical EASE-Grid modis_500m/ - subdirectory with complete set of .gpd files for MODIS 500 m tiles, also includes a single .gpd for the complete sinusoidal projection N200correct.mpp - 200 km scale Northern Hemisphere EASE-Grid mpp. All supported EASE-Grid Northern Hemisphere gpds must refer to this mpp N2conus.gpd - 2.5 km CONUS Northern Hemisphere subset EASE-Grid Na1.gpd, Na5.gpd & Na25.gpd - 1.25, 5 and 25 km AVHRR Polar Pathfinder Northern Hemisphere subset EASE-Grid Naari.gpd - 12.5 km AARI sea ice grids Northern Hemisphere subset EASE-Grid Nl.gpd - 25 km Northern Hemisphere EASE-Grid Nh.gpd - 12.5 km Northern Hemisphere EASE-Grid NModis4km.gpd - 4 km Northern Hemisphere EASE-Grid for MODIS sea ice NModis1km.gpd - 1 km Northern Hemisphere EASE-Grid for MODIS sea ice NpathP.gpd & NpathP.mpp - 100 km scale TOVS Polar Pathfinder Northern Hemisphere subset EASE-Grid; the only exception to the rule that all supported Northern Hemisphere. EASE-Grids refer to N200correct.mpp. Nrims50.gpd, Nrims75.gpd & Nrims100.gpd - 50, 75 and 100 km Arctic RIMS Northern Hemisphere subset EASE-Grids. This family of grids places the Pole down and to the right of the center of the grid, in order to match the bore-centered convention of the original EASE-Grids, uses the rotation of the original EASE-Grids (Greenwich Meridian oriented "down" from the Pole) Nrims25km.gpd, Nrims50km.gpd, Nrims100km.gpd, Nrims125km.gpd, Nrims500km.gpd - Arctic RIMS No. Hem. EASE-Grids. This family of grids places the Pole at the intersection of the center 4 grid cells, and rotates the projection (Greenwich Meridian oriented "right" from the Pole). The 25, 50 and 100 km grids are nested. S200correct.mpp - 200 km scale Southern Hemisphere EASE-Grid mpp. All supported EASE-Grid Southern Hemisphere gpds must refer to this mpp Sa1.gpd, Sa5.gpd & Sa25.gpd - 1.25, 5 and 25 km AVHRR Polar Pathfinder Southern Hemisphere subset EASE-Grid Sl.gpd - 25 km Southern Hemisphere EASE-Grid Sh.gpd - 12.5 km Southern Hemisphere EASE-Grid SModis4km.gpd - 4 km Southern Hemisphere EASE-Grid for MODIS sea ice SModis1km.gpd - 1 km Southern Hemisphere EASE-Grid for MODIS sea ice SpathP.gpd & SpathP.mpp - 100 km scale TOVS Polar Pathfinder Southern Hemisphere subset EASE-Grid; the only exception to the rule that all supported Southern Hemisphere. EASE-Grids refer to S200correct.mpp. BamberDEM1km.gpd - nsidc-0422 Antarctic 1 km Digital Elevation Model (DEM) from Combined ERS-1 Radar and ICESat Laser Satellite Altimetry GlasAntDemWgs500.gpd, GlasGrnDemWgs1km.gpd - Glas Greenland and Antarctic Digital Elevation Model (DEM) grids Ims24km.gpd, Ims4km.gpd - NOAA Interactive Multisensor Snow & Ice Mapping System (IMS) 24 km and 4 km grids Nps.mpp - Northern Hemisphere Polar Stereographic (TB and sea ice) Nps6.gpd, N3A.gpd & N3B.gpd - 6.25, 12.5 and 25 km Northern Hemisphere Polar Stereographic grids. Sps.mpp - Southern Hemisphere Polar Stereographic (TB and sea ice) Sps6.gpd, S3A.gpd & S3B.gpd - 6.25, 12.5 and 25 km Southern Hemisphere Polar Stereographic grids. NpsGrn.gpd - 25 km Greenland subset of Nps.mpp llo.gpd - lat/lon one degree grids for ISLSCP snow and sea ice. llh.gpd - lat/lon half degree grids for ISLSCP snow and sea ice. llq.gpd - lat/lon quarter degree grids for ISLSCP snow and sea ice. Na12500-CF.gpd - Chuck Fowler's version of 12.5 km AVHRR Polar Pathfinder Northern Hemisphere subset EASE-Grid (ice age data set) lrsa_geo000.5.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 0.5 arcsecond = 0.000138889 degree grid No current data product, but referenced in MODIS CLPX grids document. lrsa_geo001.0.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 1.0 arcsecond = 0.000277778 degree grid No current data product, but referenced in MODIS CLPX grids document. lrsa_geo007.5.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 7.5 arcsecond = 0.00208333 degree grid CLPX MOD02QKM, MOD09Q1, MOD13Q1 lrsa_geo015.0.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 15.0 arcsecond = 0.00416667 degree grid CLPX MOD02HKM, MOD09A1, MOD10_L2, MOD10A1, MOD10A2 lrsa_geo030.0.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 30.0 arcsecond = 0.00833333 degree grid CLPX MOD021KM, MOD03, MOD11A1, MOD35_L2 lrsa_geo180.0.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 180 arcsecond = 0.05-degree grid CLPX MOD10C1, MOD10C2 lrsa_geo360.0.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 360 arcsecond = 0.1-degree grid No current data product, but referenced in MODIS CLPX grids document. lrsa_geo720.0.gpd - CLPX LRSA Universal Transverse Mercator 720 arcsecond = 0.2-degree grid CLPX SSM/I TBs, AMSR-E TBs lrsa_utm00012.gpd - CLPX LRSA Universal Transverse Mercator 12.5 meter grid No current data product, but referenced in MODIS CLPX grids document. lrsa_utm00025.gpd - CLPX LRSA Universal Transverse Mercator 25 meter grid No current data product, but referenced in MODIS CLPX grids document. lrsa_utm00250.gpd - CLPX LRSA Universal Transverse Mercator 250 meter grid CLPX MOD02QKM, MOD09Q1, MOD13Q1 lrsa_utm00500.gpd - CLPX LRSA Universal Transverse Mercator 500 meter grid CLPX MOD02HKM, MOD09A1, MOD10_L2, MOD10A1, MOD10A2 lrsa_utm01000.gpd - CLPX LRSA Universal Transverse Mercator 1 km grid CLPX MOD021KM, MOD03, MOD11A1, MOD35_L2 lrsa_utm05000.gpd - CLPX LRSA Universal Transverse Mercator 5 km grid CLPX MOD10C1, MOD10C2 lrsa_utm12500.gpd - CLPX LRSA Universal Transverse Mercator 12.5 km grid No current data product, but referenced in MODIS CLPX grids document. lrsa_utm25000.gpd - CLPX LRSA Universal Transverse Mercator 25 km grid CLPX SSM/I TBs, AMSR-E TBs ramp.mpp - Polar Stereographic for RAMP DEM ramp1kmdem.gpd - 1km RAMP DEM V2 Polar Stereographic ramp400dem.gpd - 400m RAMP DEM V2 Polar Stereographic Ramp0125.gpd - 125m RAMP Backscatter Ramp0500.gpd - 500m RAMP Backscatter Ramp0750.gpd - 750m RAMP Backscatter Ramp1000.gpd - 1000m RAMP Backscatter Ramp1250.gpd - 1250m RAMP Backscatter Ramp1500.gpd - 1500m RAMP Backscatter Moa.mpp - Polar Stereographic for Mosaic of Antarctica Moa0125.gpd - 125m Mosaic of Antarctica Moa0750.gpd - 750m Mosaic of Antarctica 0.09degree.gpd - 0.09-degree "geographic" (Cylindrical Equidistant) (used for Science on the Sphere images in sea ice.) 0.05degree.gpd - 0.05-degree "geographic" (Cylindrical Equidistant) (MODIS products call this "Climate Modeller's Grid" CMG) 0.1degree.gpd - 0.1-degree "geographic" (Cylindrical Equidistant) 0.2degree.gpd - 0.2-degree "geographic" (Cylindrical Equidistant) 0.25degree.gpd - 0.25-degree "geographic" (Cylindrical Equidistant) 0.3degree.gpd - 0.3-degree "geographic" (Cylindrical Equidistant) 0.5degree.gpd - 0.5-degree "geographic" (Cylindrical Equidistant) 1degree.gpd - 1-degree "geographic" (Cylindrical Equidistant) 2degree.gpd - 2-degree "geographic" (Cylindrical Equidistant) Gl25000.gpd - Greenland subset of Nl grid (Northern Hemisphere 25 km EASE-Grid) kmz.gpd - rectangular grid on Cylindrical Equidistant used for displaying polar regions more clearly in google earth. M50.gpd - 50 km Global Cylindrical EASE-Grid N5.gpd - 5 km Northern Hemisphere EASE-Grid N5conus.gpd - 5 km CONUS EASE-Grid N10.gpd - 10 km Northern Hemisphere EASE-Grid N1TibP.gpd - 1 km EASE-Grid, subset of the Tibetan Plateau N2TibP.gpd - 2.5 km EASE-Grid, subset of the Tibetan Plateau N250km.gpd - Northern Hemisphere, 250 km EASE-Grid, with North Pole at intersection of center 4 cells. "New" (parameter:value) format gpd. N50.gpd - 50 km Northern Hemisphere EASE-Grid Nha.gpd - 12.5 km Northern Hemisphere EASE-Grid. 721 x 721 subset of Nh.gpd, centered at North Pole. Nva.gpd - 6.25 km Northern Hemisphere EASE-Grid. 1441 x 1441, centered at North Pole. Nups01000.gpd - 1 km Northern Hemisphere Universal Polar Stereographic. Used for UTM for regions north of 84 degrees north latitude. Sups01000.gpd - 1 km Southern Hemisphere Universal Polar Stereographic. Used for UTM for regions south of 80 degrees south latitude. S5.gpd - 5 km Southern Hemisphere EASE-Grid S50.gpd - 50 km Southern Hemisphere EASE-Grid Sha.gpd - 12.5 km Southern Hemisphere EASE-Grid, 721x721 subset of Nl.gpd, centered at South Pole. Sva.gpd - 6.25 km Southern Hemisphere EASE-Grid, 1441x1441, centered at South Pole. afghan_swe.gpd - 500 m Afghanistan EASE-Grid conus_geo030.gpd - Snow Data Assimilation System (SNODAS) Contiguous US (CONUS) 30 arc-second Cylindrical Equidistant (lat/lon) grid lhasa.gpd - 4 km Tibet Plateau region (centered on Lhasa) subset of Nl grid (Northern Hemisphere 25 km EASE-Grid) lrsa_geo1440.0.gpd - CLPX LRSA "geographic" (Cylindrical Equidistant) 0.4-degree grid lrsa_utm50000.0.gpd - CLPX LRSA Universal Transverse Mercator 50 km grid ncep.mpp - 2.5-degree NCEP Northern Hemisphere, cylindrical equidistant, centered a the International Date Line. ncep.gpd - 2.5-degree NCEP grid, Northern Hemisphere only ncep_global.mpp - 2.5-degree NCEP global, cylindrical equidistant, centered at the Greenwich Meridian ncep_global.gpd - 2.5-degree NCEP grid, Northern Hemisphere only noaa_wksn.gpd - Describes the NOAA weekly snow maps grid (89x89, polar noaa_wksn.mpp stereo) IGH1km.gpd - Interrupted Goode's Homolosine at 1 km, used for global landcover maps from EDC gigbp2_0g.img IGH8km.gpd - Interrupted Goode's Homolosine at 8 km gl_g1km.gpd - Interrupted Goode's Homolosine at 1 km, used for global landcover maps from BU gl_g.sds01.v4.bin etopo5.gpd - global 5 minute maps like etopo5.dat etopo5.mpp gtopo30.gpd - global 30 arc-second (~1 km) maps like GLOBE Mease.gpd - global 1 meter Ease-Grid Mease.mpp BergsScotiaSea250.gpd - 250 meter Lambert Conic Conformal for BergsSouthGeorgia250.gpd iceberg monitoring Moa125.gpd - 125m Mosaic of Antarctica Used for internal development at NSIDC Moa750.gpd - 750m Mosaic of Antarctica Used for internal development at NSIDC westUS2km.gpd - 2 km Western US region subset of Nl grid (Northern Hemisphere 25 km EASE-Grid) Guidelines to consider when defining new EASE-Grid gpds:
Use the new format (parameter:value, all in the .gpd, no separate .mpp file). It's easier to read and maintain.
Keep units in meters. Although mapx can handle other units, other units can cause confusion in the utilities like xytest. For clean ways to nest grids inside existing grids, see examples like Moa125.gpd and Grn250m.gpd.
Full hemisphere Azimuthal grids:
Keep the math simple wrt an existing grid. If the new grid is X times the old resolution, then make the coordinates multiply by X. Examples: N50 = Nl/2 = Nh/4 = N10/5 = N5/10.
The original rule for EASE-Grids was to ensure that the equator was properly included in the sampled coverage of the new grid (the samples being the centers of the edge cells); however, this caused problems with grid corner cells "wrapping" around the opposite pole. The EASE-Grid-2.0 recommendation is to avoid this situation by placing the equator exactly at or outside the edge cells. The original EASE-Grid defined the pole at the center of an odd number of grid cells (e.g. Nl.gpd used 721 x 721); EASE-Grid 2.0 places the pole at the intersection of the center 4 cells, in an even-numbered grid (e.g. EASE2_N25km.gpd uses 720 x 720).
The original EASE-Grid used a spherical Earth model, with R=6371.228 km. Distances in the original mpp/gpd files were in km.
EASE-Grid-2.0 uses the WGS84 ellipsoid. Keep the distances in meters.
Global grids:
-
Areal coverage:
A. Should never have overlap in the horizontal dimension, i.e. the longitude of the left edge should be exactly equal to the longitude of the right edge
B. Cannot (by definition) extend beyond the poles in the vertical dimension. Depending on the cell size, this will probably mean that the poles will not be covered. (If you care that much, you should probably be using an azimuthal grid, anyway.)
-
Refer to rules for azimuthal grids wrt nesting cells in another existing grid.
- This repository is not actively supported by NSIDC but we welcome issue submissions and pull requests in order to foster community contribution.
- None, but these files are used primarily with mapx
See LICENSE
See Code of Conduct
This software was developed by the National Snow and Ice Data Center with funding from multiple sources.
For questions or problems with these mpp/gpd files, please contact:
User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO, USA 80309-0449
Phone: +1 303-492-6199
Fax: +1 303-492-2468
E-mail: nsidc@nsidc.org