Pan-Arctic Digital Elevation Model (DEM)

Transcription

1 Pan-Arctic Digital Elevation Model (DEM) Tazio Strozzi and Maurizio Santoro Gamma Remote Sensing, Gümligen, Switzerland Annett Bartsch et al. Institute of Photogrammetry and Remote Sensing, TU Wien, Austria

2 Background As a primary source for terrain elevations a global DEM is very convenient (identifying permafrost-related landforms, modeling periglacial geomorphology, hydrology, surface energy budget, satellite images orthorectification,...). On the circum-arctic scale a minimum requirement for a DEM is 100 m grid cell resolution and a vertical accuracy of 0.5 m to be produced on a decadal scale. Such a DEM would complement the SRTM DEM at the northern latitudes >60. DEMs covering circum-arctic landscapes at a spatial grid-cell resolutions of 1 km (e.g. GETASSE, ACE, GLOBE30) are inadequate for identifying permafrost-related landforms and for image geocoding.

3 Background Version 1 of the global ASTER GDEM, created by stereocorrelating the 1.3 million archived ASTER VNIR scenes covering the Earth s land surface between latitudes 83 north and 83 south, was released in the Summer of 2009 with a spatial grid-cell resolutions of 30 m. However, due to its dependency on the availability of suitable cloud-free optical ASTER stereo images, the quality and accuracy of GDEM varies significantly globally and artifacts and voids are largely present. Thus, Version 1 of the ASTER GDEM could not be considered for our project. Complete topographic data is also freely available from various other sources.

4 Global DEMs SRTM4 for northern latitudes <60º (~90m) Russian Topographic Maps at 1:200'000 (~90m) Uploaded in Scotland by Jonathan de Ferranti. Canadian DED1 at 1: (~90m) ( GeoBase USGS DEM from 1: scale maps for Alaska (

5 Global DEMs

6 Global DEMs

7 Quality reports global DEMs SRTM-3 DEM up to 60º latitude (Rabus et al., 2003): horizontal ±20m vertical ±16m absolute and ±6m relative RTM for much of Western Europe and Asia: average elevation difference of 1.4 m and a standard deviation of 16.6 m in comparison with the National Land Survey (NLS) elevation dataset of Sweden with only very local mismatches in form of shifts of the order of a couple of hundred meters (Santoro & Cartus, 2009) CDED from 1945 to 2010: high agreement in the horizontal and the vertical directions with respect to SRTM-3 where both elevation datasets are available U.S. Geological Survey DEM (for Alaska): data gaps and stretched tiles

8 Examples 1. Lena River Delta, Sibiria, Russia: N, E 2. Yakutsk, Sibiria, Russia: N, E 3. Ob Estuary, Pechora Urals, Russia: N, E 4. Mackenzie River Delta, Northwest Territories, Canada: N, W 5. Dalton Highway, Alaska, USA: N, W

9 Lena River Delta ASTER GDEM (~30m) (

10 Lena River Delta Russian Topographic Maps (~90m) (

11 Yakutsk ASTER GDEM (~30m) (

12 Yakutsk Russian Topographic Maps (~90m) (

13 Ob Estuary ASTER GDEM (~30m) (

14 Ob Estuary Russian Topographic Maps (~90m) (

15 Dalton Highway (Alaska) ASTER GDEM (~30m) (

16 Dalton Highway (Alaska) USA National Elevation Dataset (~60m) (

17 Mackenzie River Delta ASTER GDEM (~30m) (

18 Mackenzie River Delta Canadian DED1 (~90m) (

19 Outlook: GDEM2 released in October 2011 Airborne IFSAR DEM (~5m) ASTER GDEM (~30m) USA NED (~90m) ASTER GDEM2 (~30m)

20 Outlook: Local scale DEM's Validation and improvement of circumpolar DEM On local scales, much higher resolutions (0.5 m to 10 m), accuracies (5 cm) and temporal sampling (annual scale) are necessary to detect, classify and quantify permafrost related surface features and related Data source: ERS-1/2 SAR (1 day), ERS-2 / ENVISAT ASAR (30 min.), ALOS PRISM, National topographic maps

21 ALOS PRISM DEM's Points on the surface can be extracted where the image contrast is large enough Raster size 10 m Accuracy assessment at North Burgenland (Austria): reference DEM derived by airborne laser scanning (accuracy 1 dm) median shifts for (X/Y/Z) of (-6/-5/48) [m] (absolute error) standard deviation of the height differences 2.0 m (relative error) surface points very inhomogeneously distributed

22 Yakutsk Map Ortophoto ASTER GDEM (~30m) ALOS PRISM LPS

23 Yakutsk ALOS PRISM IPF-densified (LSM)

24 Yakutsk ASTER GDEM (~30m)