Journal Article

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

Zhang, Tingjun, Wahr, John, Schaefer, Kevin, Liu, Lin

2012

Overview

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

• Publisher: Blackwell Publishing Ltd,American Geophysical Union
• Subject: 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