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Data Set ID:
NSIDC-0610

EASE-Grid 2.0 Land Cover Classifications Derived from Boston University MODIS/Terra Land Cover Data, Version 1

These data provide land cover classifications derived from the Boston University MOD12Q1 V004 MODIS/Terra 1 km Land Cover Product (Friedl et al. 2002). The data are available in various EASE-Grid 2.0 azimuthal and global projections, in multiple spatial resolutions ranging from 3 km to 100 km. The data are in flat binary, 1 byte files that are stored by row.

Geographic Coverage

Parameter(s):
  • Land Use/Land Cover > Land Use Classes > Land Cover Classification
Spatial Coverage:
  • N: 90, S: -90, E: 180, W: -180

  • N: 90, S: 0, E: 180, W: -180

  • N: 0, S: -90, E: 180, W: -180

Spatial Resolution:
  • 3 km x 3 km
  • 5 km x 5 km
  • 6.25 km x 6.25 km
Temporal Coverage:
  • 1 July 2000 to 31 December 2000
Temporal Resolution: Not specified
Data Format(s):
  • Binary
Platform(s) TERRA
Sensor(s): MODIS
Version: V1
Data Contributor(s): Mary Brodzik, Kenneth Knowles
Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Brodzik, M. J. and K. Knowles. 2011. EASE-Grid 2.0 Land Cover Classifications Derived from Boston University MODIS/Terra Land Cover Data, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/XR8523MC24TB. [Date Accessed].

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Detailed Data Description

These data sets use the International Geosphere Biosphere Programme (IGBP) land cover classes from Boston University's (BU) 1 km MOD12Q1 product (Friedl et al. 2002).  Table 1 lists the IGBP land cover classes. For each  projection/spatial resolution combination, the 1 km MOD12Q1 product is resampled to the coarser resolution grids: 3 km, 5 km, 6.25 km, 9 km, 10 km, 12.5 km, 25 km, 36 km, and 100 km. See the Data Acquisition and Processing section of this document for more information.

Table 1. IGBP Land Cover Classes
Class Number Category Class Number Category
01 Evergreen needleleaf forest 10 Grasslands
02 Evergreen broadleaf forest 11 Permanent Wetlands
03 Deciduous needleleaf forest 12 Croplands
04 Deciduous broadleaf forest 13 Urban and built-up
05 Mixed forests 14 Cropland/natural vegetation mosaic
06 Closed shrublands 15 Snow and ice
07 Open shrublands 16 Barren or sparsely vegetated
08 Woody savannas 17 Water bodies
09 Savannas
Format

The data are in flat binary, 1 byte files that are stored by row. Each of the resolution and projection combinations are described by a Grid Parameter Definition (GPD). Tables 2 and 3 list the short name for each GPD. For each GPD, there are 17 land cover files, one for each IGBP land cover class (Table 1). For the 17 land cover files, each pixel in the grids is the percent of land covered by the IGBP class noted in the file name. For example, the file EASE2_N25km.igbp_landclass.01.720x720.bin is the 25 km EASE-Grid 2.0 Northern Hemisphere file that contains a 721x721 grid where each grid cell represents the percent of land in that cell that was characterized as IGBP class 1 (Evergreen needleleaf forest). See the Data Acquisition and Processing section of this document for information on how these percents were derived. Pixels that are off the map or were undefined in the input data were given the value 255. Tables 2 and 3 list the resolution, grid dimensions, and files size for each GPD. See Table 4 for the file naming convention.

Table 2. EASE-Grid Land Classification Resolutions and Grid Sizes
Projection Resolution Grid Dimensions (r x c) File Size GPD Short Name
N., S. Hemisphere 25 km 721 x 721 508 KB Nl, Sl
12.5 km 1441 x 1441 2 MB Nh, Sh
Global 25 km 1383 x 586 792 KB Ml
12.5 km 2766 x 1171 3.1 MB Mh

Table 3. EASE-Grid 2.0 Land Classification Resolutions and Grid Sizes
Projection Parent Grid Resolution Grid Dimensions (r x c) File Size GPD Short Name

N., S. Hemisphere

100 km 100 km 180 x 180 32 KB EASE2_N100km, EASE2_S100km
10 km 1800 x 1800 3.1 MB EASE2_N10km, EASE2_S10km
5 km 3600 x 3600 13 MB EASE2_N05km, EASE2_S05km
36 km 36 km 500 x 500 245 KB EASE2_N36km, EASE2_S36km
9 km 2000 x 2000 3.9 MB EASE2_N09km, EASE2_S09km
3 km 6000 x 6000 35 MB EASE2_N03km, EASE2_S03km
25 km 25 km 720 x 720 507 KB EASE2_N25km, EASE2_S25km
12.5 km 1440 x 1440 2 MB EASE2_N12.5km, EASE2_S12.5km
6.25 km 2880 x 2880 8 MB EASE2_N6.25km, EASE2_S6.25km
3.125 5760 x 5760 33 MB EASE2_N3.125km, EASE2_S3.125km
Global 36 km 36 km 964 x 406 383 KB EASE2_M36km
9 km 3856 x 1624 6 MB EASE2_M09km
3 km 11568 x 4872 54 MB EASE2_M03km
25 km 25 km 1383 x 584 792 KB EASE2_M25km
12.5 km 2776 x 1168 3.1 MB EASE2_M12.5km
6.25 km 5552 x 2336 13 MB EASE2_M6.25km
Temperate¹ 25 km 25 km 1388 x 540 750 KB EASE2_T25km
12.5 km 2776 x 1080 3.0 MB EASE2_T12.5km
6.25 km 5552 x 2160 12 MB EASE2_T6.25km
3.125 km 11104 x 4320 50 MB EASE2_T3.125km
¹The temperate grid is a subset of the global grid that omits the most poleward latitudes. It extends from 67 N° to 67 S°.
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File and Directory Structure

EASE-Grid

Data are available via FTP in ftp://sidads.colorado.edu/pub/DATASETS/nsidc0608_classification_ease/. This directory contains a subdirectory for each EASE-Grid projection—north, south, and global—with subfolders labeled by resolution (12km, 25km). Each resolution folder contains 17 land classification files corresponding to the parent projection and resolution.

EASE-Grid 2.0

Data are available via FTP in ftp://sidads.colorado.edu/pub/DATASETS/nsidc0610_classification_ease2/. This directory contains a subdirectory for each EASE-Grid 2.0 projection—north, south, global, and temperate—with subfolders labeled by resolution (3km, 3.125km, 5km, 6.25km, etc.). Each subfolder folder contains 17 land classification files corresponding to the parent projection and resolution.

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File Naming Convention

EASE-Grid

Example File Name: Nl.igbp_landclass.01.721x721.bin
Generic File Name: Pr.igbp_landclass.CC.colxrow.bin

EASE-Grid 2.0

Example File Name: EASE2_N25km.igbp_landclass.01.720x720.bin
Generic File Name: EASE2_PRRkm.igbp_landclass.CC.colxrow.bin

The following table describes this data set's file name variables:

Table 4. File Naming Convention for the Land Classification Files
Variable Description
EASE2_ File contains EASE-Grid 2.0 data. Files without this variable contain EASE-Grid data.
P Projection. Values: N = N. Hemisphere; S = S. Hemisphere; M = global; T = temperate
EASE-Grid: r

EASE-Grid 2.0: RRkm
Resolution (EASE-Grid). h = 12.5km, l = 25km

Resolution in km (EASE-Grid 2.0). For example: 03km = 3 km; 3.125km = 3.125 km; 05km = 5 km...
igbp_landclass Land cover classification file.
CC 2-digit land cover classification code. See Table 1 for values.
colxrow Grid dimensions in pixels, column x row.
.bin Binary file extension.
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Spatial Coverage

EASE-Grid

These data cover the entire globe and are provided in projections for the entire globe and for the Northern and Southern Hemispheres. See Table 2 for a complete listing of the projection/resolution combinations.

EASE-Grid 2.0

These data cover the entire globe and are provided in projections for the entire globe and for the Northern and Southern Hemispheres. See Table 3 for a complete listing of the projection/resolution combinations.

Projection and Grid Description

These data are provided in both the EASE-grid projection and the EASE-Grid 2.0 projection. The grid sizes are given in Table 2 and Table 3, respectively. For complete details on these two projections, see the EASE-Grid Format Description and the EASE-Grid 2.0 Format Description web pages.

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Temporal Coverage

Land classifications are derived from MODIS (Version 4) data obtained between July and December, 2000 (Friedl et al. 2002).

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Parameter or Variable

These data provide land cover classifications in percent area per grid cell using the IGBP land cover classifications described in Table 1. They were derived from 1 km classifications in MOD12Q1 according to Friedl et al. 2002.

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Software and Tools

See the EASE-Grid | Geolocation Tools page for links to software and tools that geolocate and display EASE-Grid data sets.

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Data Acquisition and Processing

EASE2 LOCI Mask Example
Figure 1. Resampling Process.
On the left is the set of 1 km2 pixels from the input data that map to the coarser resolution pixels on the right. On the right is one of the coarser pixels from each of the classification files and the percent that the file contains that land classification.

These data are derived from the Boston University MODIS/Terra 1 km Land Cover product (MCD12Q1, V004), which utilizes the Interrupted Goode Homolosine projection. MCD12Q1 data are reprojected to either EASE-Grid or EASE-Grid 2.0 and resampled by counting the number of 1 km observations for each classification that map into the target coarser resolution cell. The counts are then converted to percentages and a separate map is generated for each IGBP land cover classification (see Table 1). As such, the set of land classifications for each grid/resolution comprises 17 files.

Example:
  1. To resample the 1 km MCD12Q1 data to each of the coarser EASE-Grid and EASE-Grid 2.0 resolutions, a certain number of 1 km2 cells are mapped to the given coarser-resolution cells (Figure 1).
  2. For each of the 17 coarser resolution land class files, each separate IGBP class type is counted in each of the sets of 1 km2 MCD12Q1 data. For example, if a nine-pixel set of 1 km2 cells happens to map to a coarser resolution EASE-Grid cell, as shown in Figure 1, then seven 1 km2 pixels are characterized as Class 1, two pixels are characterized as Class 2, and zero pixels are characterized as the other 15 classes. This means that this pixel in the Class 1 output data file is 7/9 (78%) covered by Class 1, that same pixel in the Class 2 file is 2/9 (22%) covered by Class 2, and that pixel in all of the other files (Class 3 to 17) is zero (Figure 1).
  3. The counts are then converted to a percent. The floating point percent values were rounded to the nearest integer percent. There were three problems with the result:
    1. Water and missing value ambiguity: Boston University used zero for water instead of the IGBP value of 17. Because this is a land product, there were large areas in the oceans that were assigned 255 (fill) instead of 0 (water). See #1 in Data Corrections Applied section for the correction used.
    2. Round-off error: The sum of the integer percent values at any pixel location ranged from 98 to 102, due to round-off error. See #2 in Data Corrections Applied section for the correction used.
    3. Anomalous water in the Ross Ice Shelf: Due to an unexplained artifact in the original 1 km data, a small number of resampled pixels with an area of about 6000 square kilometers in the middle of the Ross Ice Shelf were coded as partially open water, rather than the expected snow and ice category (IGBP class 15). See #3 in Data Corrections Applied section for the correction used.
  4. Pixels that are off the map or were undefined in the input data were given the fill value 255.
  5. Data Corrections Applied
    In order to produce a more consistent data set, NSIDC performed the following corrections:
    1. Water class 17 was derived from MOD12Q1 classes 0 through 16 with the following equation: water class = 100 - (sum of nonwater classes, 1-16)/(sum of all classes, 0-16).
    2. To adjust the round-off error, the integer sum at each pixel was normalized to 100 by examining the original floating point values and reversing what would have rounded up or down for those values with decimal parts closest to 0.5; this was only done for enough classes to achieve a sum of 100. Since non-normalized sums ranged from 98 to 102, this adjusted the rounding in any given category by at most three percentage points.
    3. The misclassified open water in the Ross Ice Shelf was changed to class 15.
    4. The pixel containing the North Pole in the Northern Hemisphere was undefined in the original data set. It was set to 100 percent water.
Error Sources

Refer to Data Corrections Applied in the Data Acquisition and Processing section.

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Version History

The following tables show the version history for these data sets.

Table 5. Version History for EASE-Grid Land Cover Classification Table 6. Version History for EASE-Grid 2.0 Land Cover Classification
Version Date Description Version Date Description
V1.0 2004 The EASE-Grid Land Cover Classification data were created as an ancillary data set, not part of the official NASA DAAC data catalog. Instead, some of the data were distributed as ancillary data via a web page and others via personal communication with the authors. V1.0 2011 The EASE-Grid 2.0 LOCI masks were created as an ancillary data set, not part of the official NASA DAAC data catalog. Instead, the data were distributed via personal communication with the authors.
V1.1 2014

These data were accessioned into the NASA DAAC catalog and given a data set ID number. During this process, NSIDC changed the title, filenames, and organization of the data to improve usability. For example, the old file name for the Northern Hemisphere 25 km class 01 file was changed as follows:

  • Nl.gl_g.sds01.v4.01.bin (old name)
  • Nl.igbp_landclass.01.721x721.bin (new name)

The algorithms and processing were not changed.

V1.1 2014 These data were accessioned into the NSIDC system and given a data set ID number. During this process, NSIDC changed the title, filenames, and organization of the data to improve usability. For example, the old file name for the Northern Hemisphere 25 km class 01 file was changed as follows:
  • EASE2_N25km.gl_g.sds01.v4.bin (old name)
  • EASE2_N25km.igbp_landclass.01.720x720.bin (new name)

The algorithms and processing were not changed.

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References and Related Publications

Contacts and Acknowledgments

Mary J. Brodzik
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA

Kenneth W. Knowles
Operational Systems, Inc.
6514 Fairways Dr.
Longmont, CO 80503 USA

Document Information

DOCUMENT CREATION DATE

October 2014

No technical references available for this data set.
No FAQs or How Tos available for this data set.

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Questions? Please contact:
NSIDC User Services
Phone: 1 303 492-6199
Email: nsidc@nsidc.org