G. Bryan Bailey, U.S. Geological Survey, USA Michael Abrams, Jet Propulsion Laboratory, USA Hiroji Tsu, ERSDAC, Japan Hiroyuki Fujisada, SILC, Japan Dean Gesch, U.S. Geological Survey, USA The New ASTER 30m Global DEM Practical Steps Toward Global DEM Interoperability Workshop Beijing, China July 2, 2008 The New ASTER 30m Global DEM

G. Bryan Bailey, U.S. Geological Survey, USA Michael Abrams, Jet Propulsion Laboratory, USA Hiroji Tsu, ERSDAC, Japan Hiroyuki Fujisada, SILC, Japan Dean Gesch, U.S. Geological Survey, USA The New ASTER 30m Global DEM Alaska Statewide DEM Workshop Anchorage, Alaska July 23, 2008

ASTER Global DEM (GDEM) Global DEM, at 30m postings, will be produced from ASTER stereo images. The GDEM will be a standard ASTER data product. It is jointly provided by Japan’s Ministry of Economy Trade and Industry (METI) and U.S. National Aeronautics and Space Administration (NASA), in cooperation with METI’s Earth Resources Data Analysis Center (ERSDAC) and the United States Geological Survey (USGS). GDEM was contributed to, and accepted by, GEO at the November ’07 Summit of Ministers. It will be available to all users at no charge to the user.

Available Global DEM Data Sets DatasetCoverageHorizontal Posting Comment GTOPO30Global1 km US Level 2 DTED Global30 m Restricted Access SRTM 60 o N to 54 o S 90 m 30m over U.S. and Its Territories ASTER GDEM 83 o N to 83 o S 30 m

GDEM Applications Disaster (flood hazard map) Hydrology (water resource management) Disaster (volcanic hazard map) Energy (oil resource exploration) Precipitation data Snow cover data Volcanic data Geological data GDEM

ASTER Advanced Spaceborne Thermal Emission and Reflection Radiometer Flies on U.S. Terra Platform Built for METI in Japan Data Processing in Japan and U.S. Instrument Command and Control by Japan and U.S. Joint Science Team

ASTER Instrument VNIR Visible/Near Infrared Radiometer # of Bands: 3 Nadir + 1 Aft-Looking Spatial Resolution: 15 m SWIR Short Wave Infrared Radiometer # of Bands: 6 Nadir Spatial Resolution: 30 m TIR Thermal Infrared Radiometer # of Bands: 5 Nadir Spatial Resolution: 90 m  Launched December 1999  Has 3 sensors and detects 14 bands of spectrum.  Ground resolution is 15m ~ 90m.

Instrument Characteristics 60 km swath; <16 day repeat cycle; stereo

Along-Track Imaging Geometry of the ASTER VNIR Nadir and Aft-Viewing Sensors Begin Acquisition of 3N Complete Acquisition of 3B Sec 27.7  705 Km Orbit Single Stereo Image 3N 3B Ground Relief Second s Km

ASTER Stereo Image Data ASTER 3N Image ASTER 3B Image

ASTER Digital Elevation Models ASTER DEM Intensity Image ASTER DEM Shade Relief Image

ASTER Data Acquisition

ASTER Data Acquisition - Alaska

ASTER GDEM Specifications Data Posting: 30 m DEM Output Format: GeoTIFF, signed 16 bits, and 1 m/DN Referenced to the WGS84/EGM96 geoid Geographic latitude and longitude Coverage: 83  N to 83  S Special DN Values : for void pixels 0 for sea water body Accuracies: 20 m with 95 % confidence for vertical data (elevation) 30 m with 95 % confidence for horizontal data (geolocation) Data Set: 22,895 1  x 1º tiles

Methodology ASTER GDEM ASTER coverage (~1.5 million scenes in summer 2008) Deeper red indicates more data accumulated. Generation of a seamless tile of DEM using all ASTER data ever acquired over the tile A seamless Tile of DEM GEOSS Both US and Japan committed to contribute to GEOSS at Capetown Summit Contribution to Global coverage Automated processing ASTER scene (60km x 60km) Tile (1 arc degree square) 1. Stereo-correlate entire ~ 1.5 million scene ASTER Archive; 2. Cloud mask to remove cloudy pixels; 3. Stack all DEMS & remove residual bad values and outliers; 4. Partition data into 1º x 1º tiles --- SRTM3 coverage

Cloud Masking Step Band 3N Cloud-masked DEM

Final Product Partitioned as 1  -by-1  Tiles ASTER DEM SRTM3 Mt. Everest Area Elevation: 8,848 m 203 scenes used No holes for ASTER DEM Many large holes for SRTM Geographic Boundaries Latitude: N26 - N27 degrees Longitude:E86 - E87 degrees Mt. Everest Peak Elevation 8815 m

Preliminary Evaluation Histogram of Difference between ASTER DEM and SRTM3 Mt. Everest Area Mean: -6.9 m Standard Deviation: 26.0 m

Susquehanna Test Site Assessment Results Prototype ASTER GDEM Number of Scenes Used to Produce Prototype ASTER GDEM 10 – 22 Scenes 1 – 9 Scenes

Susquehanna Test Site - Vertical Error Tabulations Statistics MINMAXMEANSTDEV Susque NED subtract ASTGTM Susque NED subtract ASTGTM(Numbers 1 Scene mask) Susque NED subtract ASTGTM(Numbers 2 Scene mask) Susque NED subtract ASTGTM(Numbers 3 Scene mask) Susque NED subtract ASTGTM(Numbers 4 Scene mask) Susque NED subtract ASTGTM(Numbers 5 Scene mask) Susque NED subtract ASTGTM(Numbers 6 Scene mask) Susque NED subtract ASTGTM(Numbers 7 Scene mask) Susque NED subtract ASTGTM(Numbers 8 Scene mask) Susque NED subtract ASTGTM(Numbers 9 Scene mask) Susque NED subtract ASTGTM(Numbers 10 Scene mask) Susque NED subtract SRTM Susque NED subtract L1A Oct Silcast DEM Susque NED subtract L1A May Silcast DEM

Susquehanna Test Site – GCP Comparisons Ref. Elev.ASTERNEDSRTM ASTER errNED errSRTM err Min Max Mean Std Dev

N.W. Washington Test Site Assessment Results Prototype ASTER GDEM Number of Scenes Used to Produce Prototype ASTER GDEM scenes per pixel; Mean: 21.6

N.W. Washington Test Site - Vertical Error Tabulations Statistics MINMAXMEANSTDEV Wash NED subtract ASTGTM Wash NED subtract ASTGTM(Numbers 1 Scene mask) Wash NED subtract ASTGTM(Numbers 2 Scene mask) Wash NED subtract ASTGTM(Numbers 3 Scene mask) Wash NED subtract ASTGTM(Numbers 4 Scene mask) Wash NED subtract ASTGTM(Numbers 5 Scene mask) Wash NED subtract ASTGTM(Numbers 6 Scene mask) Wash NED subtract ASTGTM(Numbers 7 Scene mask) Wash NED subtract ASTGTM(Numbers 8 Scene mask) Wash NED subtract ASTGTM(Numbers 9 Scene mask) Wash NED subtract ASTGTM(Numbers 10 Scene mask) Wash NED subtract SRTM (-150 mask) Wash NED subtract L1A June Silcast DEM Wash NED subtract L1A June Silcast DEM

N.W. Washington Test Site – GCP Comparisons Ref. elev.ASTERNEDSRTM ASTER errNED errSRTM err Min Max Mean Std Dev

ASTER GDEM Validation Validation is expected to commence in late USGS and ERSDAC will lead the effort, with support from other agencies and international collaborators. Validation Plan involves two fundamental components. –Conterminous U.S. component.  934 CONUS tiles to be compared to NED and SRTM1 DEMs.  Absolute vertical accuracy to be measured using 13,300 “GCPs on benchmarks” from the National Geodetic Survey. –International component.  Up to 200 globally distributed tiles to be evaluated using SRTM data and other available validation data sets.  Investigators from the international community interested in contributing to ASTER GDEM validation should contact the authors. GDEM distribution sites will make validation results available to the user community.

ASTER GDEM Availability Public release of the full global data set is anticipated for Spring Data will be available at no cost to all users in the spirit of the Global Earth Observing System of Systems (GEOSS). ASTER GDEM will initially be packaged in 1  x 1  tiles, though “seamless” options my be considered in the future. Current plans are for data to be jointly released as a standard ASTER data product from: – U.S. through Land Processes DAAC and EOS Data Gateway. – Japan through ERSDAC Ground Data System.