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

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<ul><li> 1. Urs Wegmller, Maurizio Santoro, Charles Werner, Tazio Strozzi and Andreas Wiesmann Gamma Remote Sensing, Gmligen, 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).</li></ul> <p> 2. </p> <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> <p>Outline 3. </p> <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> <p>Motivation 4. EET Cross-Interferogram over Kolyma River Delta area (20-Jan-2009,dt = 28min. ,B =2130 m,dDC =139Hz) </p> <ul><li>How can we interpret the interferometric phase? </li></ul> <ul><li>Can we retrieve relevant information? </li></ul> <p> 5. EET Cross-Interferometry (EET-CInSAR) Sensor parameters 6. EET Cross-Interferometry (EET-CInSAR) Orbit and CInSAR geometry 7. </p> <ul><li>Interferometric phase:(1) </li></ul> <ul><li>Phase components:(2) (casef 1=f 2 ) </li></ul> <ul><li>Casef 1 f 2: </li></ul> <ul><li>1) calculateusing (1) with flat ellipsoid 2) apply (2) using </li></ul> <p>EET Cross-Interferometry (EET-CInSAR) CInSAR phase 8. </p> <ul><li>For B perp= 2km:</li></ul> <ul><li>Height ambiguity: 4.70m </li></ul> <p>EET Cross-Interferometry (EET-CInSAR) CInSAR phase to height sensitivity 9. </p> <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 kmx 112 km </li></ul> <p>EET CInSAR DEM Generation: Po Delta 10. </p> <ul><li>Refraction: </li></ul> <ul><li> Effective height difference:</li></ul> <ul><li>Ice thickness:;for:</li></ul> <p>INSAR phase model for frozen lake 11. </p> <ul><li>ENVISAT backscatteringCross-interferogram phase </li></ul> <p>Kolyma River(20-Jan-2009, B = 2130 m,dDC =139Hz) 12. </p> <ul><li>ENVISAT backscatteringCross-interferogram phase </li></ul> <p>Kolyma River(20-Jan-2009, B = 2130 m,dDC =139Hz) bottom-fast not frozen to ground 13. </p> <ul><li>ENVISAT backscatteringIce thickness maps </li></ul> <p>Kolyma River(20-Jan-2009, B = 2130 m,dDC =139Hz) bottom-fast not frozen to ground partially bottom-fast 14. </p> <ul><li>Height below reference level (coastal height) </li></ul> <p>Bottom-fast icelake floor topography 15. </p> <ul><li>ENVISAT backscatteringCross-interferogram phase </li></ul> <p>Mackenzie River(10-Mar-2009,B = 2247 m,dDC = 344Hz) 16. </p> <ul><li>ENVISAT backscattering </li></ul> <p>Mackenzie River(10-Mar-2009,B = 2247 m,dDC = 344Hz) Section 1, incl. points measuredin 27.2-9.3.2009 by J.J. van Sanden et al. 2009 17. </p> <ul><li>Cross-interferogram phase </li></ul> <p>Mackenzie River(10-Mar-2009,B = 2247 m,dDC = 344Hz) Section 1, incl. points measuredin 27.2-9.3.2009 by J.J. van Sanden et al. 2009 +3A +3C +3B + + * + * h=0 ref. used 18. </p> <ul><li>Effective height transect (negative values correspond to ice thickness) </li></ul> <p>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. </p> <ul><li>ENVISAT backscattering </li></ul> <p>Mackenzie River(10-Mar-2009,B = 2247 m,dDC = 344Hz) Section 2, incl. points measuredin 27.2-9.3.2009 by J.J. van Sanden et al. 2009 20. </p> <ul><li>Cross-interferogram phase </li></ul> <p>Mackenzie River(10-Mar-2009,B = 2247 m,dDC = 344Hz) Section 2, incl. points measuredin 27.2-9.3.2009 by J.J. van Sanden et al. 2009 +8A +8B + + * * h=0 ref. used 21. </p> <ul><li>Effective height transect (negative values correspond to ice thickness) </li></ul> <p>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. </p> <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> <p>Conclusions 23. </p> <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> <p>Outlook</p>