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Abstract. The hydrology of thawing permafrost affects the fate of the vast amount of permafrost carbon due to its controls on waterlogging, redox status, and transport. However, regional mapping of soil water storage in the soil layer that experiences the annual freeze-thaw cycle above permafrost, known as the active layer, remains a formidable challenge over remote arctic regions. This study shows that Interferometric Synthetic Aperture Radar (InSAR) observations can be used to estimate the amount of soil water originating from the active layer seasonal thaw. Our ALOS InSAR results, validated by in situ observations, show that the thickness of the soil water that experiences the annual freeze-thaw cycle ranges from 0 to 75 cm in a 60-by-100-km area near the Toolik Field Station on the North Slope of Alaska. Notably, the spatial distribution of the soil water correlates with surface topography and land vegetation cover types. We found that pixel-mismatching of the topographic map and radar images is the primary error source in the Toolik ALOS InSAR data. The amount of pixel misregistration, the local slope, and the InSAR perpendicular baseline influence the observed errors in InSAR Line-Of-Sight (LOS) distance measurements non-linearly. For most of the study area with a percent slope of less than 5%, the LOS error from pixel misregistration is less than 1 cm, translating to less than 14 cm of error in the soil water estimates.
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Integration of GPS and InSAR Data for Resolving 3‐Dimensional Crustal Deformation
Abstract We develop an algorithm to integrate GPS and InSAR data for a 3‐dimensional crustal deformation field at the Earth's surface. In the algorithm discrete GPS data points are interpolated to obtain a 3‐dimensional continuous velocity field, which is then combined with the InSAR line‐of‐sight (LOS) velocity data pixel by pixel using the least‐squares method. Advantages of our method over previous ones are that: 1) The GPS data points are optimally interpolated by balancing a trade‐off between spatial resolution and solution stability. 2) A new algorithm is developed to estimate realistic uncertainties for the interpolated GPS velocities, to be used as weights for GPS data in GPS‐InSAR combination. 3) Realistic uncertainties for the InSAR LOS rate data are estimated and used as weights for InSAR data in GPS‐InSAR combination. 4) The ramps and/or offsets of the InSAR data are globally estimated for all the images to minimize data misfit, particularly at regions where the data overlaps. Application of this method to real data from southern California shows its capability of successfully restoring 3‐dimensional continuous deformation field from spatially limited GPS and dimensionally limited InSAR data. The deformation field reveals water withdrawal induced subsidence and drought caused uplift at various regions in southern California.
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- Award ID(s):
- 1723284
- PAR ID:
- 10448850
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Earth and Space Science
- Volume:
- 7
- Issue:
- 4
- ISSN:
- 2333-5084
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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