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MODIS Mosaic of Antarctica 2008-2009 (MOA2009) Image Map, Version 1
The MODIS Mosaic of Antarctica 2008-2009 (MOA2009) Image Map consists of two cloud-free digital image maps that show mean surface morphology and a quantitative measure of optical snow grain size on the Antarctic continent and surrounding islands using 260 orbit swaths from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on board the NASA EOS Aqua and Terra satellites.
Geographic Coverage
Parameter(s): |
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Spatial Coverage: |
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Spatial Resolution: |
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Temporal Coverage: |
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Temporal Resolution: | Not specified |
Data Format(s): |
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Platform(s) | AQUA, TERRA |
Sensor(s): | MODIS |
Version: | V1 |
Data Contributor(s): | Terry Haran, Jennifer Bohlander, Ted Scambos, Thomas Painter, Mark Fahnestock |
Metadata XML: | View Metadata Record |
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.
Haran, T., J. Bohlander, T. Scambos, T. Painter, and M. Fahnestock. 2014. MODIS Mosaic of Antarctica 2008-2009 (MOA2009) Image Map, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: https://doi.org/10.7265/N5KP8037. [Date Accessed].Literature Citation
As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.
Scambos, T., T. Haran, M. Fahnestock, T. Painter, and J. Bohlander. 2007. MODIS-based Mosaic of Antarctica (MOA) Data Sets: Continent-wide Surface Morphology and Snow Grain Size, Remote Sensing of Environment. 111. 242-257. https://doi.org/10.1016/j.rse.2006.12.020
Detailed Data Description
NSIDC and the University of New Hampshire assembled a digital image map and snow-grain-size images of the Antarctic continent and surrounding islands called the MOA2009 Image Map. It provides a nearly-perfect cloud-free view of the ice sheet, ice shelves, and land surfaces. Two image data sets were compiled: a digitally smoothed red-light band 1 of MODIS image map, also called the MOA2009 Surface Morphology Image Map were the data were acquired 1 November 2008 through 28 February 2009; and two snow grain size images derived from normalized difference of calibrated band 1 and band 2 MODIS data, also called the MOA2009 Grain Size Image Map where the data were acquired 1 November 2008 through 28 February 2009, and the 2008 MOA Grain Size Image Map where the data were acquired 1 November 2008 through 16 December 2008.
Image data are available via FTP. Image data on the FTP site are provided as 16-bit images to preserve the radiometric content of the scenes.
Grain size cell values in the range of 10 through 1100 represent mean optical snow grain size in microns; values of 5 and 1105 represent grain size values outside this range, for example, some blue ice areas, or data for which a grain size could not be computed.
The MOA2009 digital image maps are available at two spatial grid scales, 750 m and 125 m, and are provided as a gzipped flat binary 16-bit or 8-bit unsigned integer file (.img.gz
) in little-endian byte order. Each .img.gz
file has a corresponding gzipped GeoTiff (.tif.gz
). file and a corresponding ENVI header file (img.hdr
) in ASCII. Map projection parameter and grid parameter definition files (.mpp,.gpd
) are also available.
Coastlines, ice sheet grounding lines, and islands are available in the following formats: shapefiles (.shp,.shx,.dbf,.prj
), ENVI vector files (.evf
); Generic Mapping Tools (.gmt
), Keyhole Markup Language (.kml
), and ASCII text files of point locations, with the exception of islands, which are not provided as a ASCII text file of point locations.
MOA2009 Image Maps
The image maps and ancillary files are located in the ftp://sidads.colorado.edu/pub/DATASETS/nsidc0593_moa2009/
directory. In this directory, there are three files: Moa0125.gpd
, Moa0750.gpd
, and Moa.mpp
; and three folders: envi
, geotiff
, and coastlines
. The envi folder contains the .img.gz
and .img.hdr
files, the geotiff
folder contains the .tif.gz
files, and the coastlines
folder contains the .shp,.shx,.dbf,.prj., .evf, .gmt, .kml, and .txt
files. Refer to Table 2 for the list of available files.
Where:
Variable
|
Description
|
---|---|
YYYY
|
Denotes the acquisition period for a given grain size file, where YYYY can equal either:
|
*
|
Denotes that there are three format file extensions for each of these file types: .img.gz, .tif.gz, and .img.hdr . |
File Name
|
Description
|
---|---|
00README.txt |
ASCII text file containing an abbreviated explanation of the data available for download |
Moa.mpp |
Mapx Map Projection Parameters file |
Moa0125.gpd |
Mapx Grid Parameter Definition file for 125 m grid |
Moa0750.gpd |
Mapx Grid Parameter Definition file for 750 m grid |
moa125_YYYY_grn_v1.1* |
125 m weighted optical grain size image 16-bit unsigned integer little-endian flat binary |
moa125_2009_hct_v1.1* |
125 m count of MODIS scenes contributing to each moa125_2009_hp1 grid cell8-bit unsigned integer flat binary. |
moa125_2009_hp1_v1.1* |
125 m high-pass band 1 surface morphology image 16-bit unsigned integer little-endian flat binary |
moa125_2009_hwt_v1.1* |
125 m average weight applied to computed hp1 values to determine composited moa125_2009_hp1 values16-bit unsigned integer little-endian flat binary divide by 50000 to get true hwt decimal value. |
moa750_YYYY_gct_v1.1* |
750 m count of MODIS scenes contributing to each moa750_YYYY_grn grid cell8-bit unsigned integer flat binary |
moa750_YYYY_grn_v1.1* |
750 m weighted optical grain size image 16-bit unsigned integer little-endian flat binary |
moa750_YYYY_gsd_v1.1* |
750 m standard deviation of unweighted optical grain size values contributing to each valid moa750_YYYY_gmn cell16-bit unsigned integer little-endian flat binary a value of 1 indicates there were less than two valid contributing unweighted grain size values otherwise divide by 10 to get true gsd decimal value |
moa750_YYYY_gwt_v1.1* |
750 m average weight applied to computed grain size values to determine composited moa750_YYYY_grn values16-bit unsigned integer little-endian flat binary divide by 50000 to get true gwt decimal value |
moa750_2009_hct_v1.1* |
750 m count of MODIS scenes contributing to each moa750_2009_hp1 grid cell8-bit unsigned integer flat binary. |
moa750_2009_hp1_v1.1* |
750 m high-pass band 1 surface morphology image 16-bit unsigned integer little-endian flat binary |
moa750_2009_hwt_v1.1* |
750 m average weight applied to computed hp1 values to determine composited moa750_YYYY_hp1 values16-bit unsigned integer little-endian flat binary divide by 50000 to get true hwt decimal value. |
All moa125_* files were created directly from 250 meter resolution swath data that were gridded to 125 meter resolution. |
Coastlines, Grounding Lines, and Islands
The Antarctic coastlines, ice sheet grounding lines, and island files were derived from the MOA2009 surface morphology image and are located in the ftp://sidads.colorado.edu/pub/DATASETS/nsidc0593_moa2009/
directory. Inside this directory, there is a coastlines
folder. The coastlines
folder contains the .shp, .shx, .dbf, .prj, .evf, .gmt, .kml, and .txt
files. Refer to Table 3 for the list of available files.
Where:
Variable
|
Description
|
|||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
*
|
Denotes that there are up to eight format file extensions for each of these file types (coastlines, ice sheet grounding lines, and islands):
|
File Name | Description |
---|---|
moa_2009_coastline_v1.1* |
Point locations for Antarctic coastline including ice shelf calving fronts. |
moa_2009_groundingline_v1.1* |
Point locations for Antarctic grounding line. |
moa_2009_islands_v1.1* |
Point locations for Antarctic island coastlines and ice-covered island grounding lines. |
The total size of the 750 m files is approximately 112 MB uncompressed.
The total size of the 125 m files is approximately 4 GB uncompressed.
- Southernmost Latitude: 90° S
- Northernmost Latitude: 60° S
- Westernmost Longitude: 180° W
- Easternmost Longitude: 180° E
The mosaic includes all land areas and islands south of 60° S that are larger than a few hundred meters. Land areas north of 60° S and areas of ocean more than a few tens of kilometers from coastlines are masked with zero-fill.
Spatial Resolution
The input swath data from MODIS Bands 1 and 2 have a nominal resolution of 250 m; however, MOA uses a super resolution or data cumulation image stacking scheme to increase the resolution of the final product beyond that of individual MODIS scenes. The estimated resolution of the final surface morphology composite ranges between 150 m and 250 m, depending on the number of images that were stacked and how the images were weighted. See Compositing the Image Swaths via Data Cumulation in the MAO2004 Guide Documentation for more details.
Projection Description
The 125 m grid images that make up the MOA2009 Image Map are provided in the Antarctic mapping projection recommended by the Scientific Committee on Antarctic Research (SCAR). This projection is identical to the Radarsat Antarctic Mapping Project Antarctic Mapping Mission 1 Synthetic Aperture Radar Image Mosaic of Antarctica, Version 2 data set with a 125 m mosaic.
- Projection: Polar Stereographic
- Spheroid: WGS-84
- Longitude of Central Meridian: 0°
- Latitude of True Scale: 71° S
Grid Description
Table 4 below lists the dimensions (in pixels) of the 125 m and 750 m product grids, and the location of the upper left corner of the upper left cell:
Dimension | Grid (px) | Upper left corner, upper left cell (m) | |
---|---|---|---|
125 m | 750 m | ||
X | 48333 | 8056 | -3174450.0 |
y | 41779 | 6964 | 2406325.0 |
Note: South Pole is not at the center of either of these grids.
Swaths for the surface morphology and full spring-summer snow grain images were acquired 1 November 2008 through 28 February 2009. The preferred spring-only grain size mosaic was constructed from images that were acquired 1 November 2008 through 16 December 2008.
Acquisition times were restricted to between 0500 GMT and 1330 GMT to ensure that the sun is positioned to the upper right of the projection grid in all scenes across the entire continent. To maintain a roughly uniform solar elevation angle across the composite, images acquired close to the austral summer solstice were selected for the region near the 135° W longitude coastline; for images near the 45° E longitude coastline, the majority of the scenes were acquired late January through February.
The MOA images report two parameters:
- surface morphology, derived from brightness variations in MODIS Band 1 red light images;
- snow grain size, inferred from the normalized difference radiance ratio of red to near-infrared light.
Surface Morphology
The surface morphology image required many processing steps, to create a seamless and uniform mosaic from the many images that were combined to generate single grid cell values. As such, the image values no longer have a clearly quantifiable relationship to the top-of-atmosphere, red light reflectances from which they were derived. Instead, the image provides a semi-quantitative but highly consistent representation of the surface shape and approximate reflectivity, as illuminated by the sun across all surface types for the entire continent.
Snow Grain Size
Pre-processing was reduced for the grain size mosaic. This approach sacrifices the seamlessness of the red-light image to produce a truer quantitative map of radiance ratios that can be used to approximate mean snow grain size in areas with dust-free, non-shadowed snow, firn, and ice.
The investigators derived lookup table values to correct for atmospheric effects and partially correct for Bi-directional Reflectance Distribution Function (BRDF) effects, using model runs of the Santa Barbara Discrete Ordinate Radiative Transfer (DISORT) Atmospheric Radiative Transfer (SBDART) software. The lookup tables were applied to image grids of radiance ratio and solar elevation to create images of snow optical grain size. These images were then composited to produce the final images using a similar weighting scheme to the surface morphology mosaic, favoring nadir-viewed scenes.
Software and Tools
Visualizing the MOA2009 *.evf files require the use of ENVI 5.0+
You may also find the following resources and Web sites helpful when working with MOA:
Data Acquisition and Processing
See the Theory of Measurements section in the MOA2004 Guide Documentation.
See the Data Acquisition Methods section in the MOA2004 Guide Documentation.
Geolocation and Processing
See the Geolocation and Processing section in the MOA2004 Guide Documentation.
Destriping of MODIS Image Data
See the Destriping of MODIS Image Data section in the MOA2004 Guide Documentation.
Cloud Masking
See the Cloud Masking section in the MOA2004 Guide Documentation.
Compositing the Image Swaths via Data Cumulation
See the Compositing the Image Swaths via Data Cumulation section in the MOA2004 Guide Documentation.
High-Pass Filtered Surface Feature Composite
See the High-Pass Filtered Surface Feature Composite section in the MOA2004 Guide Documentation.
Optical Mean Snow Grain Size
See the Optical Mean Snow Grain Size section in the MOA2004 Guide Documentation.
Error Sources
See the Error Sources section in the MOA2004 Guide Documentation.
See the Sensor or Instrument Description section in the MOA2004 Guide Documentation.
References and Related Publications
Contacts and Acknowledgments
Terry Haran
National Snow and Ice Data Center
449 UCB, University of Colorado
Boulder, CO 80309-0449 USA
Jennifer Bohlander
Polar Science Consulting
200 Merry Hill Drive
Cary, NC 27518 USA
Ted Scambos
National Snow and Ice Data Center
449 UCB, University of Colorado
Boulder, CO 80309-0449 USA
Thomas Painter
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
Mark Fahnestock
Institute for the Study of Earth, Oceans, and Space
University of New Hampshire
Morse Hall
8 College Road
Durham, NH 03824-3525 USA
This work was supported by NASA grant NNG04GM10G, and by USGS funds supporting J. Bohlander (instigated by J. Ferrigno) during image selection and cloud clearing. The investigators also wish to thank R. Bindschadler, W. Abdalati, and J. Ferrigno for their interest and support initiating this project.
Document Information
Document Creation Date
July 2014
NSIDC User Services
Phone: 1 303 492-6199
Email: nsidc@nsidc.org