Permafrost

	The properties of frozen ground react sensitively to climate and environmental changes in high-latitude and high-altitude regions. This includes the temperature distribution in the permafrost layer and the depth of the overlying active layer where seasonal freezing and thawing occur. Changes in these quantities have important impacts on terrain stability, coastal erosion, surface and subsurface water, the carbon cycle and vegetation development.
	Domain:	Terrestrial
	Subdomain:	Cryosphere
	Scientific Area:	Snow and Ice
	ECV Steward:	Philippe Schoeneich
	Products:	Permafrost Temperature (PT); Active Layer Thickness (ALT); Rock Glacier Velocity (RGV)

Permafrost Temperature Evolution

Figure: Permafrost temperature evolution at 20 m depth at selected borehole sites: Left: Permafrost sites in Norway and the European Alps. Right: Permafrost temperature along the Qinghai-Xizang Highway on the Tibetan Plateau.

Source: BAMS report 2019 (in prep.)

ECV Products and Requirements

These products and requirements reflect the Implementation Plan 2022 (GCOS-244).

The requirements are found in the complete 2022 ECVs Requirements document as well: ECV Permafrost.

Products	°C		Permafrost Temperature (PT)
	(*)	Unit	Values
Horizontal Resolution	G	N/A (Spatial distribution of boreholes)	Regular spacing
	B		Transects / various settings
	T		Characterization of bioclimate zones
Vertical Resolution: Borehole depth	G		Deeper than ZAA
	B		Down to ZAA
	T		Below permafrost table
Vertical Resolution: Sensor spacing along borehole for continuous monitoring	G	m	Above ZAA: 0.2
	B
	T		Above ZAA: 0.5
Vertical Resolution: measuring interval for manual measurement	G	m	Below ZAA: 5 to 10
	B
	T		Below ZAA: >10
Temporal Resolution	G		Active layer: 1h; Down to ZAA: 1d; Below ZAA: 1 month
	B		Active layer: 1d; Down to ZAA: 1 month; Below ZAA: 1 year
	T		Active layer: 1 month; Down to ZAA: 1 year; Below ZAA: 5 years
Timeliness	G		Weekly /real time
	B		1 year
	T		5 years
Required Measurement Uncertainty	G	°C	0.01
	B		0.1
	T		0.2
Stability	G	°C	0.01
	B		0.05
	T		0.1

Products	cm		Active Layer Thickness (ALT)	m y-1	Rock Glacier Velocity (RGV)
					Spatial distribution of selected rock glaciers	Spatial resolution of the measurem ent. 1 value per selected rock glacier unit
	(*)	Unit	Values	Unit	Values	Values
Horizontal Resolution	G	m	Regular spacing		Regional coverage	Flow field
	B		Transects		Multiple sites in a defined regional context	Few discrete points
	T		sufficient sites to characterize each bioclimatic subzone		Isolated site	Velocity value at a point
Vertical Resolution	G	cm	2
	B		10
	T		20
Temporal Resolution	G	y	1 (at end of thawing period)	y (Frequency and Observation time window)	1 and 1
	B				1 and <1
	T		1 (at end of thawing period)		2-5 and >1
Timeliness	G	y	1	month	3
	B
	T		1		12
Required Measurement Uncertainty (2-sigma)	G	cm	1/5	%	5
	B				10
	T		2/15		20
Stability	G	cm	1	y	with overlap several years
	B		5		with overlap 1 year
	T		10		without overlap

(*) Goal (G): an ideal requirement above which further improvements are not necessary. Breakthrough (B): an intermediate level between threshold and goal which, if achieved, would result in a significant improvement for the targeted application. The breakthrough value may also indicate the level at which specified uses within climate monitoring become possible. It may be appropriate to have different breakthrough values for different uses. Threshold (T): the minimum requirement to be met to ensure that data are useful.

Data Sources

This list provides sources for openly accessible data sets with worldwide coverage for which metadata is available. It is curated by the respective GCOS ECV Steward(s). The list does not claim to be complete. Anyone with a suitable dataset who wishes it to be added to this list should contact the GCOS Secretariat.

Global Terrestrial Network for Permafrost (GTN-P) Database