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Delta-K InSAR Technique for Snow Water Equivalent Retrieval

Geir Engen(1) and Tore Guneriussen(2)

(1) Norut Informasjonsteknologi AS, PB 6434, Forskningsparken, 9294 Tromsoe, Norway
(2) University of Tromsoe, UiT, N-9037, Norway


Retrieval of Snow Water Equivalent (SWE) using conventional InSAR procssing is difficult due to InSAR phase wrapping. The InSAR phase is lost from pixel to pixel when the snow layer variation exceeds some tens of cm because of the high InSAR phase sensitivity to snow depth. This paper describes the concept of using delta-K technique on InSAR data for deriving SWE of dry snow. The main scattering contribution from a dry snow cover is from the snow-ground interface. The interferometric phase of two SAR images, one with no snow and one with dry snow cover contains information on the SWE. By performing a delta-K processing of the two SAR scenes followed by averaging an estimation of the SWE can be achieved for the averaged area with good accuracy. In this paper experimental results using ERS-1 data show that the delta-K phase can be estimated to a few degrees accuracy for an area of 10x10 km2 corresponding to roughly SWE of 100 mm. The delta-K processing is performed splitting the bands of each of the summer and winter images into two subbands in the slant range dimension. The effect of this is to give the two sub-band images two new carrier frequencies separated a small difference (delta) frequency apart. Next step is to multiply the two sub-band images together to obtain the delta-K image, one for summer and one for winter. Finally the delta-K interferometric SAR image is generated multiplying the two resulting delta- K images from summer and winter together.


Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry