Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
High-resolution remote sensing identification of thermokarst lake dynamics in a subarctic peat plateau complex
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
2010 (English)In: Canadian journal of remote sensing, ISSN 0703-8992, E-ISSN 1712-7971, Vol. 36, no 1, S26-S40 p.Article in journal (Refereed) Published
Abstract [en]

Methods to quantify the dynamics of thermokarst lake margins in subarctic permafrost peatlands have been examined using historical aerial photographs and QuickBird imagery from the Hudson Bay Lowlands in west-central Canada, spanning a time period of 52 years (1954-2006). The goal of this study was to develop a method for detection of metre-scale changes in thermokarst lake extent using a time series of high resolution imagery. The method should be applicable to a variety of lake forms, transferable to other locations and sufficiently robust as to support different data types. Semi-automatic remote sensing techniques such as unsupervised and supervised classification and texture and high-pass filtering were tested, evaluated and rejected. According to an experiment of manual digitalization of shorelines by multiple operators the relative uncertainty for lakes surrounded by peat plateau was ±1.5 m. The uncertainty was reduced to ±0.6 m when binary encoding of transects perpendicular to the shoreline was used to refine the manual delineation. This proved to be the most accurate method to detect small-scale changes in lake extent. An increased understanding and quantification of thermokarst dynamics in permafrost peatlands is important for predicting future scenarios of greenhouse gas emissions from these ecosystems under changing climatic conditions and our method supports such goals.

Place, publisher, year, edition, pages
2010. Vol. 36, no 1, S26-S40 p.
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:su:diva-42152DOI: 10.5589/m10-010ISI: 000282371000004OAI: oai:DiVA.org:su-42152DiVA: diva2:344194
Available from: 2010-08-18 Created: 2010-08-18 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Temporal and spatial dynamics in subarctic peat plateaus and thermokarst lakes
Open this publication in new window or tab >>Temporal and spatial dynamics in subarctic peat plateaus and thermokarst lakes
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Permafrost peatlands are widespread at high northern latitudes and are important soil organic carbon reservoirs. A future warming in these areas, as suggested by global climate models, can cause thawing and increased ground subsidence (thermokarst), resulting in changes in surface hydrology and ecosystem functioning. The aim of this thesis is to increase our knowledge of temporal and spatial dynamics in subarctic peat plateaus with interspersed thermokarst lakes in order to better understand how these ecosystems respond to climate change. Detailed plant macrofossil and carbon/nitrogen ratio analyses of two peat plateaus located in the continuous and northern discontinuous permafrost zones in west-central Canada show that permafrost conditions have been stable since permafrost developed around 5600–4500 cal yr BP. Peat plateaus act as carbon sinks over time. The lack of wet phases since the plateaus formed, despite several local fires, suggests that this type of peatlands have been negligible as methane sources throughout most of their history, representing a negative net radiative forcing on climate. Thermokarst lakes are common features in peat plateaus across the northern permafrost region. A time-series analysis of aerial photographs and high resolution satellite images in three peat plateau/thermokarst lake complexes along a climatic and permafrost gradient shows that where the mean annual air temperature (MAAT) is below -5ºC and ground temperatures are -2ºC or colder, only minor changes in thermokarst lake extent have occurred from the mid 1970s until the mid 2000s. During the same time interval extensive lake drainage and new lake formation has taken place where the MAAT is ca -3ºC and the ground temperature is close to 0ºC. In a future progressively warmer and wetter climate, permafrost degradation can cause significant impacts on landscape pattern and greenhouse gas exchange also in the vast peat plateaus presently experiencing stable permafrost conditions.

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography and Quaternary Geology (INK), Stockholm University, 2010. 36 p.
Series
Dissertations from the Department of Physical Geography and Quaternary Geology, ISSN 1653-7211 ; 23
Keyword
Peatlands, permafrost, subarctic, peat plateau, thermokarst lake, macrofossil analysis, carbon/nitrogen ratio, peat accumulation, carbon accumulation, remote sensing, binary encoding, time-series analysis
National Category
Natural Sciences
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-42115 (URN)978-91-7447-106-9 (ISBN)
Public defence
2010-10-01, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript.Available from: 2010-09-09 Created: 2010-08-17 Last updated: 2011-12-27Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Sannel, A. Britta K.Brown, Ian A.
By organisation
Department of Physical Geography and Quaternary Geology
In the same journal
Canadian journal of remote sensing
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 110 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf