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Landsat Data Acquisition Plan for Antarctica and Greenland. Robert Bindschadler NASA GSFC Patricia Vornberger SAIC. Landsat-7. Launched April 15, 1999 Landsat series began in 1972 16-day repeat orbit Sun-synchronous Enhanced Thematic Mapper Plus (ETM+) instrument
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Landsat Data Acquisition Planfor Antarctica and Greenland Robert Bindschadler NASA GSFC Patricia Vornberger SAIC
Landsat-7 • Launched April 15, 1999 • Landsat series began in 1972 • 16-day repeat orbit • Sun-synchronous • Enhanced Thematic Mapper Plus (ETM+) instrument • 5 visible and near infrared bands - spatial resolution of 30 m - panchromatic band at 15 m • 2 short wavelength infrared bands • 1 thermal long wavelength infrared band with 60 m resolution
Landsat-7 (cont’d) • Scan Line Corrector problem (May 2003) • SLC-off products available - standard - gap-filled - interpolated
Worldwide Reference System • Path/Row coordinate system • 233 paths • 122 rows (~ +82o latitude) • Polar convergence of paths • Increasing overlap
Availability of Antarctic Images • >16,000 ETM+ scenes collected since 1999 • Acquisition is possible from September to March • We have thumbnails of all Antarctic images • 3-band color composite • We completed manual cloud cover assessments of the majority of images • Compared to automated assessment (ACCA) Dry Valleys Drygalski Ice Tongue and clouds
Not Black & White ACCA 18% Manual 55% ACCA 82% Manual 20%
White on White Snow surface Clouds
Cloudiness • ACCA generally performs well • Manual assessments are a bit higher • When cloud cover is low, ACCA is more accurate • When cloud cover is high, ACCA is less accurate • Approximately 15% of each summer’s acquisitions are cloud-free or nearly so
Antarctic Coverage 1999-2000 6061 acquisitions 2000-2001 3307 acquisitions (2258 are asc.)
Antarctic Coverage (cont’d) 2001-2002 1335 acquisitions 2002-2003 2771 acquisitions 2003-2004 2625 acquisitions
Availability of Greenland Images • Significant collections from summers of 1999 (639 scenes), 2000 (1267 scenes), and 2001 (1255 scenes) • We have the 3-band browse images of these, and performed manual cloud assessments for 1999 & 2000 • Earth Satellite Corp. used these cloud assessments to assist in scene selection • Approx. 420 scenes were used to create the Greenland portion of the Global Orthorectified Landsat Data Set, sponsored by NASA • These are held as a special collection, available from the USGS for $12/scene (original data at regular price) • Additional scenes are available at regular price
Greenland Coverage Courtesy M.Fahnestock,Univ. of NH
Plans for Future Acquisitions ANTARCTICA: routine collection for the coast and the dynamically active areas, where change is already known, or likely to occur GREENLAND: full coverage, annually during late summer - the period of maximum melt and minimum snow cover
Glaciological Applications • Mapping of surface features: g-line, extent of ice shelves, glaciers, blue ice areas, ice shelf rifts, surface melt ponds, crevasse zones • Feature tracking using sequential images to derive ice surface velocity • Change detection - shifts in extent of mapped features - NEW fractures, melt ponds, snow cover on blue ice • Photoclinometry (“shape from shading”) derive surface elevation maps(requires control data) • Spectral information for mapping grain size distribution, surface T, cloud/ice
Thank You • For more information about Landsat 7, including SLC-off products, see: http://landsat.gsfc.nasa.gov • For more information about the Landsat global data sets, see: Tucker, C. J., Grant, D. M., and Dykstra, J. D., 2004, “NASA’s Global Orthorectified Landsat Data Set”, PE&RS, Vol.70, No.3, March 2004, pp. 313-322.