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Note: This data set was first published on the 1998 CAPS CD.
The text for this document was taken unchanged from that CD.

See also Description of Data Files.

Seasonal and annual dynamics of frozen ground, central highland of Iceland

Thora Ellen Thorhallsdottir
Institute of Biology, University of Iceland

Location: Thjorsarver, Central Highland, Iceland
Latitude: 63o 30' N
Longitude: 18o 40' W

The results of a "... 9-year study ... to investigate the seasonal and annual dynamics of frozen ground and explore the relationship with environmental factors. The presence/absence of frozen ground and active layer thickness were recorded three times over the growing season (4-7 July, 1-4 August, and 20-24 August) at 51 permanent points in different plant communities and on 12 palsas." (Thorhallsdottir 1996, p. 237)

Frozen ground and active layer depth data, with monthly thawing and freezing degree days, precipitation and snow depth, for 1983-1991. Here are the total numbers of permanent stations where measurements were made: 33 stations in 1983, 59 stations in 1984, 63 stations in 1985-91. For the active layer depth they were divided into palsa tops (2 in 1983 but 12 after that) and all other (including several different plant communities, 51 stations for most years).


Thorhallsdottir, T.E. 1996. Seasonal and annual dynamics of frozen ground in the central highland of Iceland. Arctic and Alpine Research, 28(2), p. 237-243.

Data are in text format.
Column headings are:

kjuly = proportion of stations with frozen ground 4-7 July
kjulaug = ditto on 1-4 August
kaugust = ditto on 20-24 August
aldjulyo = mean active layer depth (cm) on 4-7 July, palsas excluded
sejulyo = standard error of the mean for the above
aldjulyp and sejulyp are as above but for palsas only
aldjao = active layer depth (cm) on 1-4 August, palsas excluded
sealdjao = s.e. of above
aldjap and sealdjap are as above but for palsas only
aldaugo = mean active layer depth (cm) on 20-24 August, palsas excluded
sealdaugo = s.e. of above
aldaugp and sealdaugp are as above but for palsas only
kyrbefore = proportion of stations with frozen ground in late August 
     of the year before; months are signified by numbers, such that 
     5 = May, 6= June etc (56 means May+June)
dd5, dd6, dd7 and dd8 are monthly degree days above zero (thawing)
precip56, precip7.....etc precipitation (mm)
snow9....snow12 is snowdepth in cm for those months
frdd is frost degree days, i.e. below zero

Please cite these data as follows:

Thorhallsdottir, T.E., 1998. Seasonal and annual dynamics of frozen ground, central highland of Iceland. In: International Permafrost Association, Data and Information Working Group, comp. Circumpolar Active-Layer Permafrost System (CAPS), version 1.0. CD-ROM available from National Snow and Ice Data Center, Boulder, Colorado: NSIDC, University of Colorado at Boulder.