Studying permafrost and active layer dynamics in Tibet and Arctic by multi-temporal radar interferometry
Ph.D. Permafrost, extremely ice-rich permafrost, is vulnerable to thawing and degradation under continuous climatic warming. Generally, in permafrost region the ground surface subsides/uplifts seasonally as a result of the volumetric contraction/expansion due to moisture phase transition between the...
| Other Authors: | , , |
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| Format: | Text |
| Language: | English Chinese |
| Published: |
2019
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| Online Access: | https://julac.hosted.exlibrisgroup.com/primo-explore/search?query=addsrcrid,exact,991039874558103407,AND&tab=default_tab&search_scope=All&vid=CUHK&mode=advanced&lang=en_US https://repository.lib.cuhk.edu.hk/en/item/cuhk-2399172 |
| Summary: | Ph.D. Permafrost, extremely ice-rich permafrost, is vulnerable to thawing and degradation under continuous climatic warming. Generally, in permafrost region the ground surface subsides/uplifts seasonally as a result of the volumetric contraction/expansion due to moisture phase transition between the frozen and unfrozen soil in the active layer. In addition, the thawing of excess ground ice in the uppermost permafrost layer might trigger secular subsidence and/or the formation of thermokarst landforms. The dynamic processes between the active layer and underlying permafrost interacts with local and regional hydrological, ecological, and geomorphological processes, leading to changes in ground thermal regime and the energy exchanges between the land surface and the atmosphere. Furthermore, permafrost thaw subsidence can severely damage buildings and infrastructure stability. However, permafrost and active layer dynamics remains poorly quantified or understood both in Tibet and Arctic. The aim of this thesis is to map and quantify the gradual elevation changes in permafrost environment using multi-temporal radar interferometry and ground measurements. To achieve this goal, I selected three study sites with different permafrost landforms in Tibet and Arctic. Thermal erosion gullies, typical thermokarst landforms, are well developed on a north-facing slope of Eboling Mountain near the northern edge of Tibet. I introduced the piecewise elevation change model that includes the seasonal elevation changes and the linear subsidence trends. I incorporated the model into the developed persistent scatterer interferometry approach to exploit all repeat ALOS-1 SAR acquisitions at a fine spatial resolution of about 7 m. I found that the gradual permafrost thaw subsidence occurs both inside and around the thermal erosion gullies between 2006 and 2011. The subsidence trends were up to 3 cm/yr inside and around the thermal erosion gullies, suggesting that 28% of the study area experiences permafrost thaw processes, which is ... |
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