## EASE Grids Map Projection & Grid Definitions

### Map Projection Details

The four EASE Grid projections comprise two polar azimuthal equal-area projections for the Northern and Southern hemispheres, a global cylindrical equal-area projection, and a temperate zone cylindrical equal-area projection (Fig. 1); the temperate projection is a subset of the global projection with different latitudinal bounds. More details about these four EASE Grid projections are available in Brodzik and Knowles 2002, Brodzik et al. 2012, and Brodzik et al. 2014.

### Grid Definitions

Each EASE Grid projections can be covered by many different grids. These grids are, essentially, the parameters necessary to define a transparent piece of graph paper that is overlaid on a flat map and then anchored to it at the map origin. The following four elements completely describe a grid:

• the map projection
• the numbers of columns and rows
• the area of each grid cell
• the location of the map's origin

Any number of grid definitions can therefore be used to describe the effect of changing the "graph paper." For example, doubling the number of columns or rows doubles the resolution; see Figure 2 for an example of how this scaling can produce a family of multi-resolution grids that nest within one another. Though the user has complete flexibility to define a custom grid for any EASE Grid projection, the tables below describe some common EASE Grids in detail. More details about how to define and use these grids can be found on the FAQ page.

Table 1. 1 km Resolution EASE Grids
EASE Grid Version
Projection
Number of Columns
Number of Rows
Grid Cell Area
x-axis map coordinate of the outer edge of the upper-left pixel
y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid 2.0 Global, Equal-Area
(EPSG: 6933)
34,704 14,616 1000.90 m x 1000.90 m -17367530.45 7314540.83
Table 2. 3 km Resolution EASE Grids
EASE Grid Version
Projection
Number of Columns
Number of Rows
Grid Cell Area
x-axis map coordinate of the outer edge of the upper-left pixel
y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid 2.0 Global, Equal-Area
(EPSG: 6933)
11568 4872 3,002.69 m x 3,002.69 m -17367530.45 7314540.83
EASE-Grid 2.0 Northern Hemisphere, Lambert Azimuthal
​(EPSG: 6931)
6000 6000 3,000 m x 3,000 m -9000000.0 9000000.0
EASE-Grid 2.0 Southern Hemisphere, Lambert Azimuthal
​(EPSG: 6932)
6000 6000 3,000 m x 3,000 m -9000000.0 9000000.0
Table 3. 3.125 km Resolution EASE Grids
EASE Grid Version
Projection
Number of Columns
Number of Rows
Grid Cell Area
x-axis map coordinate of the outer edge of the upper-left pixel
y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid 2.0 Global, Equal-Area
​(EPSG: 6933)
11104 4672 3,128.16 m x 3,128.16 m -17367530.45 7307375.92
EASE-Grid 2.0 Northern Hemisphere, Lambert Azimuthal
​(EPSG: 6931)
5760 5760 3,125 m x 3,125 m -9000000.0 9000000.0
EASE-Grid 2.0 Southern Hemisphere, Lambert Azimuthal
​(EPSG: 6932)
5760 5760 3,125 m x 3,125 m -9000000.0 9000000.0
EASE-Grid 2.0 Temperate Zones, Cylindrical Equal-Area
​(EPSG: 6933)
11104 4320 3,128.16 m x 3,128.16 m -17367530.45 6756820.20
Table 4. 6.25 km Resolution EASE Grids
Grid Name
Projection
Number of Columns
Number of Rows
Grid Cell Area
x-axis map coordinate of the outer edge of the upper-left pixel
y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid 2.0
Global, Equal-Area
​(EPSG: 6933)
5552
2336
6,256.32 m x 6,256.32 m
-17367530.45
7307375.92
EASE-Grid 2.0
Northern Hemisphere, Lambert Azimuthal
​(EPSG: 6931)
2880
2880
6,250 m x 6,250 m
-9000000.0
9000000.0
EASE-Grid 2.0
Southern Hemisphere, Lambert Azimuthal
​(EPSG: 6932)
2880
2880
6,250 m x 6,250 m
-9000000.0
9000000.0
EASE-Grid 2.0
Temperate Zones, Cylindrical Equal-Area
​(EPSG: 6933)
5552
2160
6,256.32 m x 6,256.32 m
-17367530.45
6756820.20
Table 5. 9 km Resolution EASE Grids
Grid Name Projection Number of Columns Number of Rows Grid Cell Area x-axis map coordinate of the outer edge of the upper-left pixel y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid 2.0 Global, Equal-Area
​(EPSG: 6933)
3856 1624 9,008.05 m x 9,008.05 m -17367530.45 7314540.83
EASE-Grid 2.0 Northern Hemisphere, Lambert Azimuthal
​(EPSG: 6931)
2000 2000 9,000 m x 9,000 m -9000000.0 9000000.0
EASE-Grid 2.0 Southern Hemisphere, Lambert Azimuthal
​(EPSG: 6932)
2000 2000 9,000 m x 9,000 m -9000000.0 9000000.0
Table 6. 12.5 km Resolution EASE Grids
Grid Name Projection Number of Columns Number of Rows Grid Cell Area x-axis map coordinate of the outer edge of the upper-left pixel y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid Global, Equal-Area
​(EPSG: 3410)
2766 1171 12,533.76 m x 12,533.76 m -17327927.35 7338516.48
EASE-Grid Northern Hemisphere, Lambert Azimuthal
​(EPSG: 3408)
1441 1441 12,533.76 m x 12,533.76 m -9030574.08 9030574.08
EASE-Grid Southern Hemisphere, Lambert Azimuthal
​(EPSG: 3409)
1441 1441 12,533.76 m x 12,533.76 m -9030574.08 9030574.08
EASE-Grid 2.0 Global, Equal-Area
​(EPSG: 6933)
2776 1168 12,512.63 m x 12,512.63 m -17367530.45 7307375.92
EASE-Grid 2.0 Northern Hemisphere, Lambert Azimuthal
​(EPSG: 6931)
1440 1440 12,500 m x 12,500 m -9000000.0 9000000.0
EASE-Grid 2.0 Southern Hemisphere, Lambert Azimuthal
​(EPSG: 6932)
1440 1440 12,500 m x 12,500 m -9000000.0 9000000.0
EASE-Grid 2.0 Temperate Zones, Cylindrical Equal-Area
​(EPSG: 6933)
2776 1080 12,512.63 m x 12,512.63 m -17367530.45 6756820.20
Table 7. 25 km Resolution EASE Grids
Grid Name Projection Number of Columns Number of Rows Grid Cell Area x-axis map coordinate of the outer edge of the upper-left pixel y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid Global, Equal-Area
​(EPSG: 3410)
1383 586 25,067.53 m x 25,067.53 m -17334193.54 7344784.83
EASE-Grid Northern Hemisphere, Lambert Azimuthal
​(EPSG: 3408)
721 721
25,067.53 m x 25,067.53 m
-9036842.76 9036842.76
EASE-Grid Southern Hemisphere, Lambert Azimuthal
​(EPSG: 3409)
721 721 25,067.53 m x 25,067.53 m -9036842.76 9036842.76
EASE-Grid 2.0 Global, Equal-Area
​(EPSG: 6933)
1388 584 25,025.26 m x 25,025.26 m -17367530.45 7307375.92
EASE-Grid 2.0 Northern Hemisphere, Lambert Azimuthal
​(EPSG: 6931)
720 720 25,000 m x 25,000 m -9000000.0 9000000.0
EASE-Grid 2.0 Southern Hemisphere, Lambert Azimuthal
​(EPSG: 6932)
720 720 25,000 m x 25,000 m -9000000.0 9000000.0
EASE-Grid 2.0 Temperate Zones, Cylindrical Equal-Area
​(EPSG: 6933)
1388 540 25,025.26 m x 25,025.26 m -17367530.45 6756820.20
Table 8. 36 km Resolution EASE Grids
Grid Name Projection Number of Columns Number of Rows Grid Cell Area x-axis map coordinate of the outer edge of the upper-left pixel y-axis map coordinate of the outer edge of the upper-left pixel
EASE-Grid 2.0 Global, Equal-Area
​(EPSG: 6933)
964 406 36,032.22 m x 36,032.22 m -17367530.45 7314540.83
EASE-Grid 2.0 Northern Hemisphere, Lambert Azimuthal
​(EPSG: 6931)
500 500 36,000 m x 36,000 m -9000000.0 9000000.0
EASE-Grid 2.0 Southern Hemisphere, Lambert Azimuthal
​(EPSG: 6932)
500 500 36,000 m x 36,000 m -9000000.0 9000000.0

### References

Brodzik, M. J. and K. W. Knowles. 2002. “Chapter 5: EASE-Grid: A Versatile Set of Equal-Area Projections and Grids.” in Michael F.Goodchild (Ed.) Discrete Global Grids: A Web Book. Santa Barbara, California USA: National Center for Geographic Information & Analysis. https://escholarship.org/uc/item/9492q6sm.

Brodzik, M. J., B. Billingsley, T. Haran, B. Raup, M. H. Savoie. 2012. EASE-Grid 2.0: Incremental but Significant Improvements for Earth-Gridded Data Sets. ISPRS International Journal of Geo-Information, 1(1):32-45, doi:10.3390/ijgi1010032. http://www.mdpi.com/2220-9964/1/1/32.

Brodzik, M. J., B. Billingsley, T. Haran, B. Raup, M. H. Savoie. 2014. Correction: Brodzik, M. J. et al. EASE-Grid 2.0: Incremental but Significant Improvements for Earth-Gridded Data Sets. ISPRS International Journal of Geo-Information 2012, 1, 32-45. ISPRS International Journal of Geo-Information, 3(3):1154-1156, doi:10.3390/ijgi3031154. http://www.mdpi.com/2220-9964/3/3/1154.