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Circumpolar Active Layer Monitoring (CALM) Program Network, Version 1

Metadata Updated: December 1, 2022

The CALM network includes 168 active sites in both hemispheres with 15 participating countries. This network represents the only coordinated and standardized program of observations using standard measurement protocols designed to observe and detect decadal changes in the dynamics of seasonal thawing and freezing in high-latitude soils. The Intellectual Merit of this study lies in the need for long-term time series of active layer depth, ground temperature, and thaw settlement measurements at the same locations and across diverse terrain types and regions in order to identify scales of spatial variation, establish trends, and validate models.

The active layer thickness is measured by physical probing on grids ranging in size from 100 to 1000 meters, by probing at a single point or along transects or from permanently installed frost tubes and soil temperature cables. Sites include several coastal to inland transects in North America, a longitudinal array of sites across Eurasia, and individual sites in several mid-latitude, mountainous regions. The majority of the sites are in arctic tundra regions consisting of fine grained sediments. Bouldery and rocky sites in mountains are being added to the network primarily in Europe as part of the EC Permafrost and Climate in Europe (PACE) project. CALM is being considered as the part of the Global Climate Observing System (GCOS).

CALM is closely affiliated with the International Permafrost Association (IPA), several IPA working groups, and the International Tundra Experiment (ITEX). The current protocol for observing the active layer thickness is given in the published ITEX Manual and on the ITEX and IPA Web sites. These activities are part of the IPA Global Geocryological Database (GGD).

A map on the CAPS CD-ROM illustrates the locations of the 130 sites. A comprehensive metadata file for all sites is available. The CAPS CD-ROM contains detailed metadata and summary data and can be ordered from the Order Data Button and the data can be obtained from the Order External Data Button.

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

Downloads & Resources


Metadata Created Date November 12, 2020
Metadata Updated Date December 1, 2022

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date November 12, 2020
Metadata Updated Date December 1, 2022
Publisher National Snow and Ice Data Center
Identifier C1386246340-NSIDCV0
Data First Published 1991-01-01
Language en-US
Data Last Modified 2018-02-21
Category geospatial
Public Access Level public
Bureau Code 026:00
Metadata Context
Metadata Catalog ID
Schema Version
Catalog Describedby
Citation Circumpolar Active Layer Monitoring (CALM) Program Network, Version 1. Version 1. Archived by National Aeronautics and Space Administration, U.S. Government, National Snow and Ice Data Center.
Harvest Object Id 57b39596-594b-44ac-a195-49bce8741c81
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL
Metadata Type geospatial
Program Code 026:001
Source Datajson Identifier True
Source Hash 2b63cde8aabbb09f868b4b0348f8ebff9eea9ec4
Source Schema Version 1.1
Spatial 160.6 -78.51667 166.76667 -74.03333
Temporal 1991-01-01T00:00:00Z/2022-01-17T00:00:00Z

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