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Polar Stereographic Data

Data Sets in the Polar Stereographic Projection

Geocoordinate and Pixel-Area Tools

The geocoordinate and pixel-area tools described here provide the same functionality for all polar stereographic passive microwave data sets at NSIDC. They include Fortran routines for determining latitude and longitude from i,j coordinates and a pixel-area grid.


Geocoordinate Tools

The geocoordinate tools allow the user to obtain latitude/longitude coordinates from (i,j) coordinates and vice versa. The geocoordinate tools that are available are the following; click on the links for more information about that tool:


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.
Access FTP


Tool Name locate.for
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Nimbus-5 ESMR Polar Gridded Sea Ice Concentrations
Nimbus-5 ESMR Polar Gridded Brightness Temperatures
Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Snow Melt Onset Over Arctic Sea Ice from SMMR and SSM/I Brightness Temperatures
AMSR-E/Aqua Daily L3 6.25 km 89 GHz Brightness Temperature Polar Grids
AMSR-E/Aqua Daily L3 12.5 km Brightness Temperature, Sea Ice Concentration, & Snow Depth Polar Grids
AMSR-E/Aqua Daily L3 25 km Brightness Temperature & Sea Ice Concentration Polar Grids
Description Fortran executable that allows the user to enter an (i, j) coordinate, obtain the corresponding latitude/longitude coordinate, and vice versa. This executable must be run with the subroutines mapll.for and mapxy.for.
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP


Tool Name mapll.for and mapxy.for
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Nimbus-5 ESMR Polar Gridded Sea Ice Concentrations
Nimbus-5 ESMR Polar Gridded Brightness Temperatures
Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Snow Melt Onset Over Arctic Sea Ice from SMMR and SSM/I Brightness Temperatures
AMSR-E/Aqua Daily L3 6.25 km 89 GHz Brightness Temperature Polar Grids
AMSR-E/Aqua Daily L3 12.5 km Brightness Temperature, Sea Ice Concentration, & Snow Depth Polar Grids
AMSR-E/Aqua Daily L3 25 km Brightness Temperature & Sea Ice Concentration Polar Grids
Description Subroutines that are associated with the Fortran executable, locate.for. These programs need to be compiled but are not run explicitly. They are called by locate.for; thus, the user should compile these programs with locate.for, and then use locate to do the conversions.
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP


Tool Name psn06lats_v3.dat and pss06lats_v3.dat (Note on Versions)1
Applicable Data Sets AMSR-E/Aqua Daily L3 6.25 km 89 GHz Brightness Temperature Polar Grids
Description Grids that determine the latitude of a given pixel for the 6.25 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). These latitude grids are in binary format and are stored as 4-byte integers (little endian) scaled by 100,000 (divide the stored value by 100,000 to get decimal degrees). Each array location (i, j) contains the latitude value at the center of the corresponding data grid cells.

psn06lats_v3.dat: 1216 columns x 1792 rows, range = [31.011, 89.959]
pss06lats_v3.dat: 1264 columns x 1328 rows, range = [-39.264, -89.959]
Access FTP


Tool Name psn06lons_v3.dat and pss06lons_v3.dat (Note on Versions)1
Applicable Data Sets AMSR-E/Aqua Daily L3 6.25 km 89 GHz Brightness Temperature Polar Grids
Description Grids that determine the longitude of a given pixel for the 6.25 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemispere). These longitude grids are in binary format and are stored as 4-byte integers (little endian) scaled by 100,000 (divide the stored value by 100,000 to get decimal degrees). Each array location (i, j) contains the longitude value at the center of the corresponding data grid cells. An East-longitude convention is used; therefore, positive longitude values are to the east of Greenwich, England.

psn06lons_v3.dat: 1216 columns x 1792 rows, range = [-180.000, 179.953]
pss06lons_v3.dat: 1264 columns x 1328 rows, range = [-179.955, 179.955]
Access FTP


Tool Name psn12lats_v3.dat and pss12lats_v3.dat (Note on Versions)1
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
AMSR-E/Aqua Daily L3 12.5 km Brightness Temperature, Sea Ice Concentration, & Snow Depth Polar Grids
Description Grids that determine the latitude of a given pixel for the 12.5 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). These latitude grids are in binary format and are stored as 4-byte integers (little endian) scaled by 100,000 (divide the stored value by 100,000 to get decimal degrees). Each array location (i, j) contains the latitude value at the center of the corresponding data grid cells.

psn12lats_v3.dat: 608 columns x 896 rows, range = [31.041, 89.918]
pss12lats_v3.dat: 632 columns x 664 rows, range = [-39.297, -89.918]
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP


Tool Name psn12lons_v3.dat and pss12lons_v3.dat (Note on Versions)1
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
AMSR-E/Aqua Daily L3 12.5 km Brightness Temperature, Sea Ice Concentration, & Snow Depth Polar Grids
Description Grids that determine the longitude of a given pixel for the 12.5 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). These longitude grids are in binary format and are stored as 4-byte integers (little endian) scaled by 100,000 (divide the stored value by 100,000 to get decimal degrees). Each array location (i, j) contains the longitude value at the center of the corresponding data grid cells. An East-longitude convention is used; therefore, positive longitude values are to the east of Greenwich, England.

psn12lons_v3.dat: 608 columns x 896 rows, range = [-180.000, 179.907]
pss12lons_v3.dat: 632 columns x 664 rows, range = [-179.909, 179.909]
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP


Tool Name psn25lats_v3.dat and pss25lats_v3.dat (Note on Versions)1
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Nimbus-5 ESMR Polar Gridded Sea Ice Concentrations
Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data
Nimbus-5 ESMR Polar Gridded Brightness Temperatures
Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Near Real-Time DMSP SSM/I Daily Polar Gridded Sea Ice Concentrations
Snow Melt Onset Over Arctic Sea Ice from SMMR and SSM/I Brightness Temperatures
AMSR-E/Aqua Daily L3 25 km Brightness Temperature & Sea Ice Concentration Polar Grids
Description Grids that determine the latitude of a given pixel for the 25 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). These latitude grids are in binary format and are stored as 4-byte integers (little endian) scaled by 100,000 (divide the stored value by 100,000 to get decimal degrees). Each array location (i, j) contains the latitude value at the center of the corresponding data grid cells.

psn25lats_v3.dat: 304 columns x 448 rows, range = [31.102, 89.836]
pss25lats_v3.dat: 316 columns x 332 rows, range = [-39.364, -89.836]
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP


Tool Name psn25lons_v3.dat and pss25lons_v3.dat (Note on Versions)1
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Nimbus-5 ESMR Polar Gridded Sea Ice Concentrations
Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data
Nimbus-5 ESMR Polar Gridded Brightness Temperatures
Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Near Real-Time DMSP SSM/I Daily Polar Gridded Sea Ice Concentrations
Snow Melt Onset Over Arctic Sea Ice from SMMR and SSM/I Brightness Temperatures
AMSR-E/Aqua Daily L3 25 km Brightness Temperature & Sea Ice Concentration Polar Grids
Description Grids that determine the longitude of a given pixel for the 25 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). These longitude grids are in binary format and are stored as 4-byte integers (little endian) scaled by 100,000 (divide the stored value by 100,000 to get decimal degrees). Each array location (i, j) contains the longitude value at the center of the corresponding data grid cells. An East-longitude convention is used; therefore, positive longitude values are to the east of Greenwich, England.

psn25lons_v3.dat: 304 columns x 448 rows, range = [-180.000, 179.814]
pss25lons_v3.dat: 316 columns x 332 rows, range = [-179.818, 179.818]
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP



Pixel-Area Grids

The pixel-area tools that are availabe are the following:

Please note that the data ranges given here are latitude and longitude values for the center of each grid cell. The range covered by the full grid extends to the pole (90 degrees latitude) and all longitudes (0 to 360 degrees longitude). Also note that corrected grids for the northern hemisphere were created June 22, 1999 and should replace the three psn25*.dat files that were distributed prior to this date.

To determine the lat/lon values of corresponding (i,j) data grid cells:

  1. Read in the array as long (4-byte) integers.
  2. Divide these values by 100,000. The resulting array gives the lat/lon values for the data grid cells in decimal degree

 

Tool Name psn06area_v3.dat and pss06area_v3.dat (Note on Versions)1
Applicable Data Sets AMSR-E/Aqua Daily L3 6.25 km 89 GHz Brightness Temperature Polar Grids
Description Grids that determine the area of a given pixel for the 6.25 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). The arrays are in binary format and are stored as 4-byte integers scaled by 1000 (divide by 1000 to get square km).

psn06lons_v3.dat: 1216 columns x 1792 rows
pss06lons_v3.dat: 1264 columns x 1328 rows
Access FTP


Tool Name psn12area_v3.dat and pss12area_v3.dat (Note on Versions)1
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
AMSR-E/Aqua Daily L3 12.5 km Brightness Temperature, Sea Ice Concentration, & Snow Depth Polar Grids
Description Grids that determine the area of a given pixel for the 12.5 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). The arrays are in binary format and are stored as 4-byte integers scaled by 1000 (divide by 1000 to get square km).

psn12area_v3.dat: 608 columns x 896 rows
pss12area_v3.dat: 632 columns x 664 rows
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP


Tool Name psn25area_v3.dat and pss25area_v3.dat (Note on Versions)1
Applicable Data Sets DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Nimbus-5 ESMR Polar Gridded Sea Ice Concentrations
Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data
Nimbus-5 ESMR Polar Gridded Brightness Temperatures
Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I
Near Real-Time DMSP SSM/I Daily Polar Gridded Brightness Temperatures
Near Real-Time DMSP SSM/I Daily Polar Gridded Sea Ice Concentrations
Snow Melt Onset Over Arctic Sea Ice from SMMR and SSM/I Brightness Temperatures
AMSR-E/Aqua Daily L3 25 km Brightness Temperature & Sea Ice Concentration Polar Grids
Description Grids that determine the area of a given pixel for the 25 km grids for either hemisphere (psn for the Northern Hemisphere and pss for the Southern Hemisphere). The arrays are in binary format and are stored as 4-byte integers scaled by 1000 (divide by 1000 to get square km).

psn25area_v3.dat: 304 columns x 448 rows
pss25area_v3.dat: 316 columns x 332 rows
Access Brightness Temperature Data Sets: FTP
Sea Ice Data Sets: FTP

 

 

1 Version 3 (V3) pixel area files, developed by NASA Goddard Space Flight Center (GSFC), provide a more accurate mapping of area for the polar stereographic grid. V3 and V2 area files differ by a maximum of approximately 0.5 sq km per grid cell at the corners of the grid. The effect on total extent and total area estimates is, at most, 10,000 sq km (approximately ~0.1%).