NASA Distributed Active Archive Center (DAAC) at NSIDC

EASE-Grid Data

Data Sets in the Equal-Area Scalable Earth Grid

Geolocation Tools

See Also

This document describes how to geolocate North, South, and Global EASE-Grid data products using ENVI software.

This document describes how to import Passive Microwave EASE-Grid data into ArcGIS.

The tables on this page provide links to software and tools for geolocating and displaying EASE-Grid data sets available at NSIDC.

The software and tools are grouped into the following categories:

  • NSIDC DataViewer - Interactive tool for viewing and displaying satellite images for a variety of passive microwave data
  • Geolocation Software - Including C, FORTRAN, and IDL (Interactive Data Language) conversion software
  • Geolocation Data Files - Look-up files that contain arrays with the latitude and longitude at the center of each grid cell


Please note that the look-up files for EASE-Grid data sets contain arrays with the latitude and longitude at the center of each grid cell. Users who need software to perform the conversion for any location, not just the center of each cell, can choose from the tools listed below or can obtain the Map Transformations Library (Mapx) software.

NSIDC DataViewer

Tool Name dataviewer.tar.gz 
Applicable Data Sets
Polar Stereographic Projection
Near-Real-Time DMSP SSM/I-SSMIS Daily Polar Gridded Brightness Temperatures
DMSP SSM/I-SSMIS Daily Polar Gridded Brightness Temperatures
Near-Real-Time DMSP SSM/I-SSMIS Daily Polar Gridded Sea Ice Concentrations
Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS
Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data
AMSR-E/Aqua Daily L3 25 km Brightness Temperature & Sea Ice Concentration Polar Grids

EASE-Grid Projection
Near-Real-Time SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Nimbus-7 SMMR Pathfinder Daily EASE-Grid Brightness Temperatures
AMSR-E/Aqua Daily EASE-Grid Brightness Temperatures
Northern Hemisphere EASE-Grid 2.0 Weekly Snow Cover and Sea Ice Extent Version 4

Quarter-Degree Projection
AMSR-E/Aqua Daily Global Quarter-Degree Gridded Brightness Temperatures
Description The NSIDC DataViewer is an interactive tool for viewing and displaying satellite images from select NSIDC passive microwave data sets. Images in PNG, JPEG, TIFF, and other commonly used image data formats can also be viewed and displayed in a user-defined grid.

Up to 64 images can be displayed simultaneously in the DataViewer resizeable graphics window, allowing data users to page through a series of images. Images can be scaled and manipulated either individually or as a group. By moving the cursor over an image, a data user can obtain the latitude and longitude coordinates as well as the image value at the cursor location. After an image or series of images is manipulated, the contents of the graphics window(s) can be saved in a variety of image formats, including PostScript, PNG, JPEG, and TIFF.

The DataViewer is a program written in Interactive Data Language (IDL). It can be run in IDL with an IDL license, via the freely distributed IDL Virtual Machine, or as a run-time application.

Please Note:
  • DataViewer produces a scaling error with time values in DMSP-F17 SSMIS time (.tim) files. When using SSMIS .tim files, please be advised that data points will display as 1/10th of their actual value.
  • DataViewer is currently incompatible with data obtained using the Polaris search and subsetter tool.
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Geolocation Software [top]  

Tool Name easeconv.pro (Located in easeconv-0.3.tgz)

(With the help file, easconv_help.html, for data set users with IDL)
Tool Type IDL
Applicable Data Sets AARI 10-Day Arctic Ocean EASE-Grid Sea Ice Observations
AMSR-E/Aqua Daily EASE-Grid Brightness Temperatures
AMSR-E/Aqua Daily L3 Global Snow Water Equivalent EASE-Grids

AMSR-E/Aqua 5-Day L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Monthly L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Daily L3 Surface Soil Moisture, Interpretive Parms, & QC EASE-Grids
Nimbus-7 SMMR Pathfinder Daily EASE-Grid Brightness Temperatures
DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Global Monthly EASE-Grid Snow Water Equivalent Climatology
Near-Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent
Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent Version 4
TOVS Pathfinder Path-P Daily and Monthly Polar Gridded Atmospheric Parameters

Description This program, currently at Version 0.3, contains routines to convert between latitude/longitude and row/column coordinates.
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Tool Name ezlhconv.c

(With header file, ezlhconv.h, for data set users with knowledge of C programming)
Tool Type C
Applicable Data Sets AMSR-E/Aqua Daily EASE-Grid Brightness Temperatures
AMSR-E/Aqua Daily L3 Global Snow Water Equivalent EASE-Grids

AMSR-E/Aqua 5-Day L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Monthly L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Daily L3 Surface Soil Moisture, Interpretive Parms, & QC EASE-Grids
Nimbus-7 SMMR Pathfinder Daily EASE-Grid Brightness Temperatures
DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Global Monthly EASE-Grid Snow Water Equivalent Climatology
Near-Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent
Description Subroutines in these files can be called from the user's main program, to convert between latitude/longitude and row/column coordinates.
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Tool Name ezlhconv.f

(For data set users with knowledge of FORTRAN programming)
Tool Type FORTRAN
Applicable Data Sets AMSR-E/Aqua Daily EASE-Grid Brightness Temperatures
AMSR-E/Aqua Daily L3 Global Snow Water Equivalent EASE-Grids

AMSR-E/Aqua 5-Day L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Monthly L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Daily L3 Surface Soil Moisture, Interpretive Parms, & QC EASE-Grids
Nimbus-7 SMMR Pathfinder Daily EASE-Grid Brightness Temperatures
DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Global Monthly EASE-Grid Snow Water Equivalent Climatology
Near-Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent
Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent Version 3

Description Subroutines in these files can be called from the user's main program, to convert between latitude/longitude and row/column coordinates.
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Geolocation Data Files [top]

For data set users who only have need of the latitude and longitude of the center of any cell in the grid, geolocation data files contain flat, binary arrays of 4-byte integers containing the latitude or longitude of the respective grid cell, in hundred-thousandth degrees. The user should divide the stored integer value by 100,000. to yield decimal degrees, with 1 meter precision. The user is expected to know which byte-ordering convention is required by their system. Files are provided in PC (little-endian/LSB) byte orders.

File Naming Convention

Geolocation data files are named according to the following convention, and as described in the following table:

ggpppooo

where:

Variable Description
gg grid name (NL, NH, SL, SH, ML, MH, NAARI, Na25, Sa25)
ppp parameter (LAT, LON)
ooo byte order (LSB: Least Significant Byte/litte-endian, MSB: Most Significant Byte/big-endian 1)
1 As of January 2012, EASE-Grid geolocation files are no longer provided in MSB byte order.


Example geolocation data file name
: MLLATLSB

Depending on the coverage area, which varies for different grids (such as ML, NH, SL, Sa25 and so on), scaled latitudes range from -90.00000 to 90.00000, and scaled longitudes range from -180.00000 to 180.00000 with missing data (such as corners of grids with hemispheric coverage) indicated by scaled value 14316.55765.

 

Tool Names MLLATooo and MLLONooo
Tool Type Geolocation Data Files
Applicable Data Sets AMSR-E/Aqua Daily L3 Surface Soil Moisture, Interpretive Parms, & QC EASE-Grids
AMSR-E/Aqua Daily EASE-Grid Brightness Temperatures
DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Nimbus-7 SMMR Pathfinder Daily EASE-Grid Brightness Temperatures

Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name ML
Coverage Global
Resolution 25 km
Dimensions 1383 x 586 pixels
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Tool Names MHLATooo and MHLONooo
Tool Type Geolocation Data Files
Applicable Data Sets DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name MH
Coverage Global
Resolution 12.5 km
Dimensions 2766 x 1171 pixels
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Tool Names NLLATooo and NLLONooo
Tool Type Geolocation Data Files
Applicable Data Sets DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Nimbus-7 SMMR Pathfinder Daily EASE-Grid Brightness Temperatures
AMSR-E/Aqua Daily L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua 5-Day L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Monthly L3 Global Snow Water Equivalent EASE-Grids
Global Monthly EASE-Grid Snow Water Equivalent Climatology
Near-Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent
Northern Hemisphere EASE-Grid Weekly Snow Cover and Sea Ice Extent Version 3

Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name NL
Coverage Northern Hemisphere
Resolution 25 km
Dimensions 721 x 721 pixels
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Tool Names NHLATooo and NHLONooo
Tool Type Geolocation Data Files
Applicable Data Sets DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name NH
Coverage Northern Hemisphere
Resolution 12.5 km
Dimensions 1441 x 1441 pixels
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Tool Names SLLATooo and SLLONooo
Tool Type Geolocation Data Files
Applicable Data Sets AMSR-E/Aqua Daily EASE-Grid Brightness Temperatures
DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures

Nimbus-7 SMMR Pathfinder Daily EASE-Grid Brightness Temperatures
Global Monthly EASE-Grid Snow Water Equivalent Climatology
AMSR-E/Aqua Daily L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua 5-Day L3 Global Snow Water Equivalent EASE-Grids
AMSR-E/Aqua Monthly L3 Global Snow Water Equivalent EASE-Grids
Near-Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent

Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name SL
Coverage Southern Hemisphere
Resolution 25 km
Dimensions 721 x 721 pixels
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Tool Names SHLATooo and SHLONooo
Tool Type Geolocation Data Files
Applicable Data Sets DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures
Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name SH
Coverage Southern Hemisphere
Resolution 12.5 km
Dimensions 1441 x 1441 pixels
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Tool Names NAARILATooo and NAARILONooo
Tool Type Geolocation Data Files
Applicable Data Sets AARI 10-Day Arctic Ocean EASE-Grid Sea Ice Observations
Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name NAARI
Coverage Subset of the Northern Hemisphere
Resolution 25 km
Dimensions 721 x 721 pixels
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Tool Names Na25LATooo and Na25LONooo
Tool Type Geolocation Data Files
Applicable Data Sets Polar Pathfinder Daily 25 km EASE-Grid Sea Ice Motion Vectors
National Ice Center Arctic Sea Ice Charts and Climatologies in Gridded Format
AVHRR Polar Pathfinder Twice-Daily 25 km EASE-Grid Composites

Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name Na252
Coverage Subset of the Northern Hemisphere
Resolution 25 km
Dimensions The Na25 EASE-Grid is a subset of the 25 km Northern Hemisphere Azimuthal EASE-Grid, including the center 361 columns by 361 rows, with the North Pole at the center of the center-most grid cell. For a complete grid description, please refer to the Summary of NOAA/NASA Polar Pathfinder Grid Relationships Web page.
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Tool Names Sa25LATooo and Sa25LONooo
Tool Type Geolocation Data Files
Applicable Data Sets Polar Pathfinder Daily 25 km EASE-Grid Sea Ice Motion Vectors
National Ice Center Arctic Sea Ice Charts and Climatologies in Gridded Format
AVHRR Polar Pathfinder Twice-Daily 25 km EASE-Grid Composites
Description Provides latitude and longitude for the center of any cell in the grid. For additional details, please refer to the Geolocation Data Files section of this Web page.
Grid Name Sa252
Coverage Subset of the Southern Hemisphere
Resolution 25 km
Dimensions The Sa25 EASE-Grid is a subset of the 25 km Northern Hemisphere Azimuthal EASE-Grid, including the center 321 columns by 321 rows, with the North Pole at the center of the center-most grid cell. For a complete grid description, please refer to the Summary of NOAA/NASA Polar Pathfinder Grid Relationships Web page.
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2 For information on how the Polar Pathfinder grids are related to one another, see the NOAA/NASA Polar Pathfinder Data Web page.