Focal point: Jerry Brown
temperature reflects integrated changes in ground surface
energy balance, in turn reflecting possible climate
refers to earth materials that remain at or below 0°C
for at least two consecutive years. In the Northern Hemisphere,
permafrost regions occupy approximately 23 million km2,
with permafrost underlying between 12 and 17 million km2.
These areas include large regions of Canada, China, Mongolia,
Russia and Alaska, and with smaller permafrost areas at
higher elevations in mountain chains of many other countries
in both the Northern and Southern Hemispheres. The thickness
of permafrost can exceed 600 m in the high latitudes. Southward,
permafrost thins and becomes discontinuous. Unlike snow
and ice covers, permafrost is not easily observed remotely,
and requires in situ observations to define its extent and
of permafrost and active layer
monitoring is conducted mainly through ground-based, point
measurements. Permafrost thermal state (i.e. ground temperature)
and active layer thickness are the key permafrost variables
identified for monitoring under the GCOS/GTOS programmes.
The Global Terrestrial Network for Permafrost (GTN-P), approved
in 1999 and coordinated by the International Permafrost
Association (IPA), comprises two international monitoring
networks: Thermal State of Permafrost (TSP) and Circumpolar
Active Layer Monitoring (CALM). More than 15 countries participate
in these networks.
temperature data are essential for detecting the terrestrial
climate signal in permafrost terrain. The temperature signal
in permafrost provides an indication of integrated changes
in the ground surface energy balance, that in turn may reflect
changes in climate. Many permafrost temperature records
are of short duration and discontinuous, but some sites
have continuous time series 20 to 30 years long.
extent and plans
majority of the monitoring sites are located in the high
latitude and high altitude regions of the Northern Hemisphere.
Existing and new sites in Antarctica and the subantarctic
are being added. The GTN-P is largely composed of regional
networks, including the Mackenzie region in Canada; an Alaskan
transect and deep boreholes in northern Alaska; the Permafrost
and Climate in Europe (PACE) programme of boreholes, largely
in alpine permafrost; and regional networks in China, Russia
125 sites, in both hemispheres contribute to CALM, which
has operated for the last decade. The more recently established
TSP has identified over 550 boreholes that can potentially
contribute to GTN-P. Metadata and site information are available
for many of these candidate boreholes (see GTN-P Web site).
Both TSP and CALM are included in the International Polar
Year (IPY) programme Permafrost Observatory Project (#50).
Permafrost temperature measurements at many sites are planned
for 2007–2008 to obtain a “snapshot” as
a contribution to the IPY.
commitment, however, is required to establish a permanent
network of permafrost observatories as part of GTN-P.
products and coordination
international funding is available explicitly for data management,
and so this has been done largely on a voluntary basis.
Management and dissemination of active layer data for CALM
is currently supported through a grant from the U.S. National
Science Foundation. Data management for TSP is partially
supported by the Geological Survey of Canada through its
research programmes. Both CALM and TSP contribute soil temperature
and moisture data to the Terrestrial Ecosystem Monitoring
Sites (TEMS) database. Several IPY proposals are pending,
and, if funded, will provide additional resources for producing
a comprehensive retrospective and contemporary database
on the state of permafrost. IPA coordinates GTN-P activities
with other international programmes, including the World
Climate Research Programme - (WCRP-CliC) and the Integrated
Global Observing Straregy – Cryosphere (IGOS - Cryo).
GTN-P Site selection criteria
selected meet the GCOS/GTOS hierarchical system for surface
observations, of the Global Hierarchical Observing Strategy
as well as meeting the following criteria:
1. Site data well documented
and freely available.
Well-documented methodologies employed.
Reasonable assurance for long-term measurements.
Sites in under-represented areas have priority.
Readily accessible sites with long-established research
and funding commitments preferred.
Participation in the GCOS/GTOS networks will facilitate
use of the data by international organizations such as the
Intergovernmental Panel on Climate Change (IPCC)
and the Arctic Climate Impact Assessment (ACIA),
and improve justification for national and multi-national
funding. The initial role of the IPA permafrost network
is to organize the systematic collection and distribution
of standardized data. The Geological
Survey of Canada is providing the international
data management for the GTN-P borehole temperature monitoring
programme and maintains the GTN-P
web site on its Permafrost internet
site. Metadata for network sites will be accessible
as well as regularly submitted summary data. GTN-P data
would be subsequently archived through the National
Snow and Ice Data Centre, Boulder, Colorado,
as part of the IPA's Global Geocryological Database. Summaries
and interpretations of data will be prepared every five
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