Observations of glacier dynamics with PALSAR DATA

Transcription

1 Observations of glacier dynamics with PALSAR DATA Tazio Strozzi, Urs Wegmüller and Charles Werner Gamma Remote Sensing, Gümligen, Switzerland Rhodes, Greece, 3 to 7 November 2008

2 Outline ESA GLOBGLACIER project Offset tracking of satellite SAR images Case studies in the Arctic: Novaya Zemlya, Svalbard, Alaska, Baffin Island Conclusions and recommendations

3 GLOBGLACIER The ESA GlobGlacier project is attempting to establish a service for glacier monitoring from space that complements the existing network for global glacier monitoring GlobGlacier products have been identified by the user group: - digital glacier outlines - terminus position - topography - changes in glacier surface elevation - snow covered area and elevation of the transient snowline - velocity fields Velocity fields for glaciers will be obtained either from feature tracking of repeat pass optical imagery or active microwave sensors using differential SAR interfeometry or SAR offsettracking

4 Offset tracking of satellite SAR images With offset tracking the registration offsets of two SAR images in both slant-range (i.e. in the line-of-sight of the satellite) and azimuth (i.e. along the orbit of the satellite) directions are generated and used to estimate the displacement of glaciers Offset-tracking is a robust and direct alternative technique to InSAR for the estimation of glacier motion in the case of rapid flow and large acquisition time intervals

5 Offset tracking of satellite SAR images 0 pixel _ range azimuth offset tracking PALSAR 46 days original offsets flight direction (azimuth x) line-of-sight (range R) ΔR z B R sinθ z=3000m, B =300m, ΔR=2m d Δx ~ ( ΔTotalElectonContent dx ) / fo2

6 Offset tracking of satellite SAR images 0 pixel _ range azimuth offset tracking PALSAR 46 days filterered offsets flight direction (azimuth x) co-registration with DEM filter line-of-sight (range R)

7 Offset tracking of satellite SAR images Swiss Alps / days 300 m 0 m/year 250

8 Grosse Aletschgletscher (Switzerland) 0 m/year * 4.67 m / sin (38) 500 m 192 * 3.15 m 600 m > PALSAR 128 * 1.36 m / sin (44) 250 m 128 * 1.98 m 250 m > TSX ALOS PALSAR days, 300 m TerraSAR-X days, 280 m ERS-1/ (1 day, 34 m)

9 Gornergletscher (Switzerland) PALSAR / m/year <5 50 >500 Gamma Portable Radar Interferometer ERS 07/ (horizontal plane) time interval ~1 hour

10 Novaya Zemlya (Russia) ALOS PALSAR (L-band, 46 days repeat cycle) Time series analysis Track 525, Frame 1520

11 Novaya Zemlya (Russia) 0 m/year 300 Offset tracking _ ALOS PALSAR FBS-FBS 46 days Background is MODIS imagery from July 29, 2003 Outlet glacier boundaries are after The catalogue of glaciers of the USSR (1978)

12 Novaya Zemlya (Russia) 0 m/year 300 Offset tracking _ ALOS PALSAR FBD-FBD 46 days Background is MODIS imagery from July 29, 2003 Outlet glacier boundaries are after The catalogue of glaciers of the USSR (1978)

13 Novaya Zemlya (Russia) 0 m/year 300 Offset tracking _ ALOS PALSAR FBD-FBD 46 days Background is MODIS imagery from July 29, 2003 Outlet glacier boundaries are after The catalogue of glaciers of the USSR (1978)

14 Novaya Zemlya (Russia) 0 m/year 300 Offset tracking _ ALOS PALSAR FBD-FBS 92 days Background is MODIS imagery from July 29, 2003 Outlet glacier boundaries are after The catalogue of glaciers of the USSR (1978)

15 Novaya Zemlya (Russia) 0 m/year 300 Offset tracking _ ALOS PALSAR FBS-FBS 46 days Background is MODIS imagery from July 29, 2003 Outlet glacier boundaries are after The catalogue of glaciers of the USSR (1978)

16 0 m/year 300 Novaya Zemlya (Russia) Velocity (m/year) _ _ _ _ _ Velocity (m/year) _ _ _ _ _ Velocity (m/year) _ _ _ _ _

17 Vestfonna-Austfonna, Svalbard (Norway) N 3-dim. Ascending orbits ALOS PALSAR offsettracking 0 m/year 300 Expected errors are about ±10 m/year 2 Tracks / (W) / (E) 46 days

18 Vestfonna-Austfonna, Svalbard (Norway) N 3-dim. Ascending / descending orbits ERS INSAR & offsettracking 0 m/year 300 Expected errors are about ±2 cm/day (±7 m/year) 4 Tracks Dec. 95 / Jan day

19 Vestfonna-Austfonna, Svalbard (Norway) N 3-dim. Descending orbits JERS-1 SAR offsettracking 0 m/year 300 Expected errors are about ±20 m/year 2 Tracks / (W) / (E) 44 days

20 Vestfonna-Austfonna, Svalbard (Norway) N 3-dim. Ascending orbits ALOS PALSAR 2 Tracks / (W) / (E) 46 days

21 Kenai Peninsula, Alaska (USA) ALOS PALSAR (L-band, 46 days repeat cycle)

22 Kenai Peninsula, Alaska (USA) Offset tracking _ ALOS PALSAR FBS-FBS 46 days 0 m/year 300

23 Kenai Peninsula, Alaska (USA) ERS InSAR _ day -134 m descending orbit _ not yet available 2π

24 Chigmit Mountains, Alaska (USA) ALOS PALSAR (L-band, 46 days repeat cycle)

25 Chigmit Mountains, Alaska (USA) Offset tracking _ ALOS PALSAR FBS-FBS 46 days 0 m/year 300

26 Chigmit Mountains, Alaska (USA) ERS InSAR _ day -73 m descending orbit 2π

27 Baffin Island (Canada) ALOS PALSAR (L-band, 46 days repeat cycle)

28 Baffin Island (Canada) Offset tracking _ ALOS PALSAR, FBS-FBS, 46 days 0 m/year 100

29 Baffin Island (Canada) 0 m/year 100 Offset tracking _ ALOS PALSAR, FBS-FBS, 46 days

30 Baffin Island (Canada) InSAR _ ALOS PALSAR, FBS-FBS, 46 days

31 Baffin Island (Canada) InSAR _ ERS-1/2 SAR, 1 day

32 Outlook and recommendations Use of ALOS PALSAR FBS and FBD data for the estimation of the motion of glaciers with offset tracking resulted in remarkably good outcomes in many regions around the world. For a more global use of ALOS PALSAR data in glacier dynamics the acquisition of a more consistent set of image pairs separated by a full orbital cycle of 46 days is required over glacier-covered regions, in particular in the Arctic. The ALOS PALSAR acquisition strategy features routine observations, that are currenlty not fully adapted to glacier motion studies. Is there the possibility to update the ALOS PALSAR acquisition strategy at continental scale in Arctic and Antarctic regions?

33 Thank you for your attention