InSAR time series analysis of seasonal surface displacement dynamics on the Tibetan Plateau
<p>Climate change and the associated rise in air temperature have affected the Tibetan Plateau to a significantly stronger degree than the global average over the past decades. This has caused deglaciation, increased precipitation and permafrost degradation. The latter in particular is associa...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2020-05-01
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Series: | The Cryosphere |
Online Access: | https://www.the-cryosphere.net/14/1633/2020/tc-14-1633-2020.pdf |
Summary: | <p>Climate change and the associated rise in air temperature have
affected the Tibetan Plateau to a significantly stronger degree than the
global average over the past decades. This has caused deglaciation,
increased precipitation and permafrost degradation. The latter in particular
is associated with increased slope instability and an increase in
mass-wasting processes, which pose a danger to infrastructure in the
vicinity. Interferometric synthetic aperture radar (InSAR) analysis is well
suited to study the displacement patterns driven by permafrost processes, as
they are on the order of millimeters to decimeters. The Nyainqêntanglha
range on the Tibetan Plateau lacks high vegetation and features relatively
thin snow cover in winter, allowing for continuous monitoring of those
displacements throughout the year. The short revisit time of the Sentinel-1
constellation further reduces the risk of temporal decorrelation, making it
possible to produce surface displacement models with good spatial coverage.
We created three different surface displacement models to study heave and
subsidence in the valleys, seasonally accelerated sliding and linear creep
on the slopes. Flat regions at Nam Co are mostly stable on a multiannual
scale but some experience subsidence. We observe a clear cycle of heave and
subsidence in the valleys, where freezing of the active layer followed by
subsequent thawing cause a vertical oscillation of the ground of up to a few
centimeters, especially near streams and other water bodies. Most slopes of
the area are unstable, with velocities of 8 to 17 mm yr<span class="inline-formula"><sup>−1</sup></span>. During the
summer months surface displacement velocities more than double on most
unstable slopes due to freeze–thaw processes driven by higher temperatures
and increased precipitation. Specific landforms, most of which have been
identified as rock glaciers, protalus ramparts or frozen moraines,
reach velocities of up to 18 cm yr<span class="inline-formula"><sup>−1</sup></span>. Their movement shows little
seasonal variation but a linear pattern indicating that their displacement
is predominantly gravity-driven.</p> |
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ISSN: | 1994-0416 1994-0424 |