Thermokarst Formation

This map represents the proportion of the landscape where thermokarst (depression from soil collapse due to permafrost thaw) could initiate and expand under warming climate at a 1km resolution. The general hypothesis underlying the development of this model is that thermokarsts occur in lowland peatland with ice rich permafrost.

The predisposition of an area to thermokarst depends of: (1) the presence of permafrost, (2) the ice content of the permafrost, (3) the physiography of the area (lowland versus upland), and (4) the presence of histels.

Predisposing factors Permafrost distribution and ice content were assessed from two different sources for Alaska (Jorgenson et al. 2008) and Canada (Brown et al. 1997). Both sources are polygon shapefiles describing permafrost extent and ice content in several discontinuous classes. The classes describing permafrost extent can be related to a range of percent cover. Both sources have similar classification of permafrost extent and ice content but different spatial resolution. The average polygon sizes are 323 km2 and 10,330 km2 in Alaska and Canada respectively. The mosaic of both maps was resampled at a 1km resolution.

Lowland were defined as follow: (1) the lower point within each watersheds was identified; (2) from this point, lowland was defined as the area connected to this point with a slope <= 4 degree. Data source used to construct the lowland map at a 60m resolution are described in page 4 of the model description (PredispModelDesc.pdf, included in data download). This map has been resampled at a 1km resolution by converting the 60m presence/absence of lowland into percent cover.

The distribution of histel has been assessed from the northern circumpolar soil carbon database from Hugelius et al. 2013. This map is a polygon shapefile giving the percent cover of histel. The average size of the polygons is 436 km2. This map has been resampled at a 1km resolution.

Thermokarst model: In areas with high to moderate ice content, the proportion of the area (1km pixel) predisposed to thermokarst is the maximum percent cover among histel, lowland and permafrost percent cover. In areas with low or variable ice content, the proportion of area predisposed is 10% of the maximum percent cover among histel, lowland and permafrost percent cover.

Data and Resources

Additional Info

Spatial resolution

1000 meters

Temporal extent

Start date: June 2014

End date: June 2014

Credits

The following people worked on producing this data set:

  • Helene Genet
  • David McGuire
  • ATM Group
  • Yujin Zhang
  • This research is funded by the Arctic Landscape Conservation Cooperative, Western Alaska Landscape Conservation Cooperative, and Northwest Boreal Landscape Conservation Cooperative (LCCs) and the Alaska Climate Science Center.
Field Value
Source http://data.snap.uaf.edu/data/IEM/other/thermokarst/
Maintainer Hélène Genet
Version 1.0.0
access_constraints []
bbox-east-long -111.25894
bbox-north-lat 71.34142000000001
bbox-south-lat 51.34819553970801
bbox-west-long -173.49206
contact-email hgenet@alaska.edu
coupled-resource []
credits ["Helene Genet", "David McGuire", "ATM Group", "Yujin Zhang", "This research is funded by the Arctic Landscape Conservation Cooperative, Western Alaska Landscape Conservation Cooperative, and Northwest Boreal Landscape Conservation Cooperative (LCCs) and the Alaska Climate Science Center."]
dataset-reference-date [{"type": "creation", "value": "2014-06-26T00:00:00"}]
download-url http://data.snap.uaf.edu/data/IEM/other/thermokarst/
frequency-of-update asNeeded
graphic-preview-description thumbnail
graphic-preview-file IEM_monthly_temp_hist_s.png
graphic-preview-type png
guid e7ca8856-d272-4953-9e80-46097196d06e
licence []
license Creative Commons Attribution 4.0
license_url http://creativecommons.org/licenses/by/4.0/
metadata-date 2016-12-12T13:36:48
metadata-language
progress
resource-type
responsible-party [{"name": "Institute of Arctic Biology", "roles": ["pointOfContact"]}]
spatial {"type": "Polygon", "coordinates": [[[-173.49206, 51.3481955397], [-111.25894, 51.3481955397], [-111.25894, 71.34142], [-173.49206, 71.34142], [-173.49206, 51.3481955397]]]}
spatial-data-service-type
spatial-reference-system 3338
spatial-resolution 1000
spatial-resolution-units meters
spatial_harvester true
temporal-extent-begin 2014-06-26T00:00:00
temporal-extent-end 2014-06-26T00:00:00