Urs Wegmüller, Maurizio Santoro, Charles Werner, Tazio Strozzi and Andreas Wiesmann Gamma Remote Sensing, Gümligen, Switze...
<ul><li>Motivation </li></ul><ul><li>ERS – ENVISAT Cross-Interferometry (EET-CInSAR) </li></ul><ul><li>Ice thickness estim...
<ul><li>Significant interest in information on Tundra lakes and frozen rivers </li></ul><ul><li>Freezing of tundra lakes a...
EET Cross-Interferogram over Kolyma River Delta area (20-Jan-2009,  dt = 28min. ,  B  =  2130 m,  dDC =  139Hz) <ul><li>H...
EET Cross-Interferometry (EET-CInSAR) Sensor parameters
EET Cross-Interferometry (EET-CInSAR) Orbit and CInSAR geometry
<ul><li>Interferometric phase:  (1) </li></ul><ul><li>Phase components:  (2) (case  f 1  =  f 2 ) </li></ul><ul><li>Case  ...
<ul><li>For B perp  = 2km:  </li></ul><ul><li>Height ambiguity: 4.70m </li></ul>EET Cross-Interferometry (EET-CInSAR) CInS...
<ul><li>Topographic phase is shown  </li></ul><ul><li>EET pair on 31-Dec-2008 </li></ul><ul><li>dtime 28 min. </li></ul><u...
<ul><li>Refraction: </li></ul><ul><li>“ Effective height difference:  </li></ul><ul><li>Ice thickness:  ;  for  :  </li></...
<ul><li>ENVISAT backscattering  Cross-interferogram phase </li></ul>Kolyma River  (20-Jan-2009,   B  = 2130 m,  dDC =  13...
<ul><li>ENVISAT backscattering  Cross-interferogram phase </li></ul>Kolyma River  (20-Jan-2009,   B  = 2130 m,  dDC =  13...
<ul><li>ENVISAT backscattering  Ice thickness maps </li></ul>Kolyma River  (20-Jan-2009,   B  = 2130 m,  dDC =  139Hz)   ...
<ul><li>Height below reference level (coastal height) </li></ul>Bottom-fast ice    lake floor topography
<ul><li>ENVISAT backscattering  Cross-interferogram phase </li></ul>Mackenzie River  (10-Mar-2009,  B  = 2247 m,  dDC = 3...
<ul><li>ENVISAT backscattering </li></ul>Mackenzie River  (10-Mar-2009,  B  = 2247 m,  dDC = 344Hz)   Section 1, incl. po...
<ul><li>Cross-interferogram phase </li></ul>Mackenzie River  (10-Mar-2009,  B  = 2247 m,  dDC = 344Hz)   Section 1, incl....
<ul><li>Effective height transect (negative values correspond to ice thickness) </li></ul>Mackenzie River  (10-Mar-2009,  ...
<ul><li>ENVISAT backscattering </li></ul>Mackenzie River  (10-Mar-2009,  B  = 2247 m,  dDC = 344Hz)   Section 2, incl. po...
<ul><li>Cross-interferogram phase </li></ul>Mackenzie River  (10-Mar-2009,  B  = 2247 m,  dDC = 344Hz)   Section 2, incl....
<ul><li>Effective height transect (negative values correspond to ice thickness) </li></ul>Mackenzie River  (10-Mar-2009,  ...
<ul><li>EET pairs with 2km and 28’ time interval   coherence often high over frozen lakes   high sensitivity of CINSAR t...
<ul><li>In 2007/08 and 2008/09 suitable EET pairs were acquired over quite many northern sites, so that the presented meth...
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TU1.L10.2 - ESTIMATION OF ICE THICKNESS OF TUNDRA LAKES USING ERS–ENVISAT CROSS-INTERFEROMETRY

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TU1.L10.2 - ESTIMATION OF ICE THICKNESS OF TUNDRA LAKES USING ERS–ENVISAT CROSS-INTERFEROMETRY

  1. 1. Urs Wegmüller, Maurizio Santoro, Charles Werner, Tazio Strozzi and Andreas Wiesmann Gamma Remote Sensing, Gümligen, Switzerland ESTIMATION OF ICE THICKNESS OF TUNDRA LAKES USING ERS – ENVISAT CROSS-INTERFEROMETRY This work was supported by ESA under contract 22526/09/I-LG. ERS and ASAR data copyright ESA (CAT 6744).
  2. 2. <ul><li>Motivation </li></ul><ul><li>ERS – ENVISAT Cross-Interferometry (EET-CInSAR) </li></ul><ul><li>Ice thickness estimation methodology </li></ul><ul><li>Results over Kolyma area, Siberia </li></ul><ul><li>Results over Mackenzie area, Canada </li></ul><ul><li>Conclusions </li></ul>Outline
  3. 3. <ul><li>Significant interest in information on Tundra lakes and frozen rivers </li></ul><ul><li>Freezing of tundra lakes and rives relevant for several applications reaching from ice road planning to environmental consideration and climate change </li></ul><ul><li>One important parameter is the ice-thickness </li></ul><ul><li>Space-borne SAR has shown significant potential already over tundra areas </li></ul><ul><li>ERS – ENVISAT Cross-Interferometry (EET-CInSAR) data available over tundra areas </li></ul><ul><li>Coherence over frozen lakes is usually high and phase looks different from surrounding, indicating some potential to derive information </li></ul>Motivation
  4. 4. EET Cross-Interferogram over Kolyma River Delta area (20-Jan-2009, dt = 28min. , B  = 2130 m, dDC = 139Hz) <ul><li>How can we interpret the interferometric phase? </li></ul><ul><li>Can we retrieve relevant information? </li></ul>
  5. 5. EET Cross-Interferometry (EET-CInSAR) Sensor parameters
  6. 6. EET Cross-Interferometry (EET-CInSAR) Orbit and CInSAR geometry
  7. 7. <ul><li>Interferometric phase: (1) </li></ul><ul><li>Phase components: (2) (case f 1 = f 2 ) </li></ul><ul><li>Case f 1  f 2 : </li></ul><ul><li>1) calculate using (1) with flat ellipsoid 2) apply (2) using </li></ul>EET Cross-Interferometry (EET-CInSAR) CInSAR phase
  8. 8. <ul><li>For B perp = 2km: </li></ul><ul><li>Height ambiguity: 4.70m </li></ul>EET Cross-Interferometry (EET-CInSAR) CInSAR phase to height sensitivity
  9. 9. <ul><li>Topographic phase is shown </li></ul><ul><li>EET pair on 31-Dec-2008 </li></ul><ul><li>dtime 28 min. </li></ul><ul><li>B  1754 m </li></ul><ul><li>dDC 958 Hz </li></ul><ul><li>ambiguity height 5.4 m </li></ul><ul><li>Area shown 96 km x 112 km </li></ul>EET CInSAR DEM Generation: Po Delta
  10. 10. <ul><li>Refraction: </li></ul><ul><li>“ Effective height difference: </li></ul><ul><li>Ice thickness: ; for : </li></ul>INSAR phase model for frozen lake
  11. 11. <ul><li>ENVISAT backscattering Cross-interferogram phase </li></ul>Kolyma River (20-Jan-2009, B  = 2130 m, dDC = 139Hz)
  12. 12. <ul><li>ENVISAT backscattering Cross-interferogram phase </li></ul>Kolyma River (20-Jan-2009, B  = 2130 m, dDC = 139Hz) bottom-fast not frozen to ground
  13. 13. <ul><li>ENVISAT backscattering Ice thickness maps </li></ul>Kolyma River (20-Jan-2009, B  = 2130 m, dDC = 139Hz) bottom-fast not frozen to ground partially bottom-fast
  14. 14. <ul><li>Height below reference level (coastal height) </li></ul>Bottom-fast ice  lake floor topography
  15. 15. <ul><li>ENVISAT backscattering Cross-interferogram phase </li></ul>Mackenzie River (10-Mar-2009, B  = 2247 m, dDC = 344Hz)
  16. 16. <ul><li>ENVISAT backscattering </li></ul>Mackenzie River (10-Mar-2009, B  = 2247 m, dDC = 344Hz) Section 1, incl. points measured in 27.2-9.3.2009 by J.J. van Sanden et al. 2009
  17. 17. <ul><li>Cross-interferogram phase </li></ul>Mackenzie River (10-Mar-2009, B  = 2247 m, dDC = 344Hz) Section 1, incl. points measured in 27.2-9.3.2009 by J.J. van Sanden et al. 2009 +3A +3C +3B + + * + * h=0 ref. used
  18. 18. <ul><li>Effective height transect (negative values correspond to ice thickness) </li></ul>Mackenzie River (10-Mar-2009, B  = 2247 m, dDC = 344Hz) X: value from J.J. van Sanden et al., 2009 * h=0 ref. used *
  19. 19. <ul><li>ENVISAT backscattering </li></ul>Mackenzie River (10-Mar-2009, B  = 2247 m, dDC = 344Hz) Section 2, incl. points measured in 27.2-9.3.2009 by J.J. van Sanden et al. 2009
  20. 20. <ul><li>Cross-interferogram phase </li></ul>Mackenzie River (10-Mar-2009, B  = 2247 m, dDC = 344Hz) Section 2, incl. points measured in 27.2-9.3.2009 by J.J. van Sanden et al. 2009 +8A +8B + + * * h=0 ref. used
  21. 21. <ul><li>Effective height transect (negative values correspond to ice thickness) </li></ul>Mackenzie River (10-Mar-2009, B  = 2247 m, dDC = 344Hz) X: value from J.J. van Sanden et al., 2009 * h=0 ref. used *
  22. 22. <ul><li>EET pairs with 2km and 28’ time interval  coherence often high over frozen lakes  high sensitivity of CINSAR to ice thickness ( h amb,ice  3m) </li></ul><ul><li>From unwrapped CINSAR phases relative to a point on the coast representing the lake(-ice) surface level, ice thickness maps can be derived (for highly transparent fresh-water ice) </li></ul><ul><li>In the case of bottom-fast ice (i.e. ice frozen to the ground) this corresponds to the mapping of the lake floor topography </li></ul><ul><li>For frazil ice (snow/water mixture) and for ice covered by wet snow or water, and for sea ice the dominant scattering is not from the ice/water or ice/lake ground interface, so that the presented methodology is not applicable </li></ul><ul><li>The comparison with a few in-situ measured ice thickness values confirmed the potential </li></ul>Conclusions
  23. 23. <ul><li>In 2007/08 and 2008/09 suitable EET pairs were acquired over quite many northern sites, so that the presented methodology may be applied elsewhere </li></ul><ul><li>Acquiring further EET pairs after Oct. 2010 is not foreseen </li></ul>Outlook

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