Service Interruption

The NSIDC Web site and data services are currently having intermittent problems and may be unavailable. We are working to restore these services as soon as possible and apologize for any inconvenience this may cause. Please contact NSIDC User Services for assistance.

File format and structure:

Canadian Geothermal Data Collection - Deep permafrost temperatures and thickness of permafrost

Modified by Alan E. Taylor from the scheme of Dr. Alan M. Jessop

The attached scheme is a hierarchic structure for organizing temperature data from deep permafrost wells along with the associated metadata. This is based on the scheme developed in 1996 by Dr. Alan M. Jessop for the digital Canadian Geothermal Database.

Overview of file structure

The primary file is the SITE FILE, giving location and other data pertinent to the site. This data does not change between various measurements made on a site or well. In digital form, these files have filenames such as S123-4, where the "S" indicates a site file, and the "123-4" refers to site number 123, subsite 4 (i.e. borehole 4 at site 123).

The secondary file is the LOG FILE, identifying by dates the set of temperature measurements undertaken on the well specified in the SITE file. These files contain details (dates, accuracies) of each log. In digital form, these have filenames such as L123-4.

The tertiary files are the OBSERVATION FILES, giving the actual measurements or observations taken, at the site specified in the SITE file and on the dates specified in the LOG file. While Jessop's scheme has a variety of observation files, for the purposes of CAPS, only temperature files (in digital form filenames such as T123-4), site topography file (TOP123-4) and site description file (D123-4) are provided. These, respectively, give the temperature observations at that site, a digital topography (as available) and general site description (as available). All sites have at least a temperature file. Other Observation files may be added later.

Finding data for sites of interest

The GSC file numbers (e.g. 123) are keys to the database. Maps (Figures 1-9) and Table 1 facilitate locating sites of interest. A user then need only to note the site number (e.g. 123) and get the Sxxx file, Lxxx and Txxx files (and other files that may be available).

The following describes the data presented and their format in each of the file sets described above: Formats used for the "Canadian Geothermal Data Collection - Deep permafrost temperatures and thickness of permafrost" database

(modified from scheme of Dr. A.M. Jessop, 1996)

Quantity            format              first     length

SITE FILE.......................................................

Line 1:
Site number         NNNNN               1         5
Well number         NN                  7         2
Site name           48A                 10        48
Industry name       48A                 59        48
Latitude            NNN-NN.N            114       8
Longitude           NNNN-NN.N           123       9
UTM                 NN NNNNNN NNNNNN    (not used)
Location accuracy   NNNN      (m)       (not used)
Ground elev'n ASL   NNNNNN    (m)       169       6
KB above ground     NNN       (m)       176       3
Total Depth TD (gnd)NNNNNN    (m)       180       6
Date of drill start yymmdd              187       6
Date drilling end   yymmdd              194       6
Date well abandonmt yymmdd              201       6

LOG FILE........................................................

Site number         NNNNN               1         5
Well number         NN                  7         2
Log number          NNN                 10        3
Type of log16A14         16
Date of log         yymmdd              31        6
Depth accuracy      N.NN                38        4
Units (m or %)      A                   43        1
Temp. accuracy      N.NN                45        4
Comments            100A                50        100

.....Note that this format allows many logs per site, each identified with
a date, etc.

TEMPERATURE FILE................................................

Site number         NNNNN               1         5
Well number         NN                  7         2
Log number          NNN                 10        3
Measured depth      NNNN.N (m)          14        6
Vertical depth      NNNN.N (m)          21        6
Temperature         NNN.NNN (oC)        28        7

.....Note that this format accommodates many logs on various dates (key
the "log number" to the LOG file for date).

SITE TOPOGRAPHY FILE.....(FIRST LINE)...........................

(N.B. Parameters here are those used in the "Topo correction" known to terrestrial heat flow researchers; these parameters construct a rough digital topography surrounding the well. See, Jaeger, J.C., 1965. Application of the theory of heat conduction to geothermal measurements. In, W.H.K. Lee, ed., Terrestrial heat flow, Geophysical monograph series vol. 8, AGU, Washington, DC. NOTE THAT THIS FILE CONSISTS OF A "FIRST LINE" AND "SUBSEQUENT LINES"...

Site number         NNNNN               1         5
Well number         NN                  7         2
Log number          NNN                 10        3
Increment of radius NNNN.N (m)          14        6
Inc'mt of elevation NNNN.N (m)          21        6
Inc'mt of azimuth   NNN    (degrees)    28        3
Collar height 
     above datum    NNNN.N (m)          32        6
Measured thermal 
     gradient       N.NNNN (mK/m)       39        6
Lapse rate          N.NNNN (mK/m)       46        6
Collar temperature  NNN.NN (oC)         53        6 (note change)
Water temperature   NNN.NN (oC)         60        6
Age of water body   NNN.N (kyear)       66        5


Site number         NNNNN               1         5
Well number         NN                  7         2
Log number          NNN                 10        3
Azimuth             NNN (degrees)       14        3
Starting radius
     increment      NNN (increments)    18        3
Elevation data
     25 per line    b,NN.N (x25 inc'mt) 26        125

SITE DESCRIPTION FILE...........................................

Site number         NNNNN               1         5
Well number         NN                  7         2
Site description    140A                11        140
     (as many lines as needed)

N.B. This file can contain any information or description that does not seem to fit elsewhere (e.g. metadata).