Estimating 1992-2000 average active layer thickness on the Alaskan North Slope from remotely sensed surface subsidence

• Published in: Journal of Geophysical Research: Earth Surface Vol. 117; no. F1
• Main Authors: Liu, Lin, Schaefer, Kevin, Zhang, Tingjun, Wahr, John
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.03.2012; American Geophysical Union
• Subjects: active layer; Algorithms; Cryosphere; Earth sciences; Earth, ocean, space; Exact sciences and technology; In situ measurement; InSAR; Organic matter; Permafrost; Radio; Remote sensing; Soil degradation; soil moisture; Soil texture; Subsidence; surface subsidence; Thawing; Tundra; Vertical distribution; Water content; United States; Arctic region; polar regions; Alaska; Northern Alaska; Prudhoe Bay; North Slope; thawing; models; active layer; textures; interferometry; Vertical distribution; degradation; monitoring; North America; Layer thickness; Long term; Measurement in situ; tundra; permafrost; Radar observation; organic materials; subsidence; water content; spatial resolution; Polar region; soils; uncertainties; Synthetic aperture radar; Retrieval algorithm
• ISSN: 0148-0227; 2169-9003; 2156-2202; 2169-9011
• DOI: 10.1029/2011JF002041

The measurement of temporal changes in active layer thickness (ALT) is crucial to monitoring permafrost degradation in the Arctic. We develop a retrieval algorithm to estimate long‐term average ALT using thaw‐season surface subsidence derived from spaceborne interferometric synthetic aperture radar (InSAR) measurements. Our algorithm uses a model of vertical distribution of water content within the active layer accounting for soil texture, organic matter, and moisture. We determine the 1992–2000 average ALT for an 80 × 100 km study area of continuous permafrost on the North Slope of Alaska near Prudhoe Bay. We obtain an ALT of 30–50 cm over moist tundra areas, and a larger ALT of 50–80 cm over wet tundra areas. Our estimated ALT values match in situ measurements at Circumpolar Active Layer Monitoring (CALM) sites within uncertainties. Our results demonstrate that InSAR can provide ALT estimates over large areas at high spatial resolution. Key Points Thawing of active layer causes surface subsidence Surface subsidence from InSAR can be used to estimate active layer thickness Our active layer thickness estimates closely match ground measurements