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Latest Revision: 19 October 1998
A. The files in this directory contain daily visual ice observations taken at National Oceanic and Atmospheric Administration/National Ocean Service water level gauge sites in the Great Lakes Basin from 1955 to the 1997. Observations are made by cooperative observers who record ice observations while logging water level gauge data for the National Ocean Service, November 1 - April 30 of each year. Please see section F for the instructions on recording the ice conditions. Ice reports were first tabulated by the US Army Corps of Engineers Lake Survey Center in Detroit, then by the Lake Survey Center as part of ESSA, then by the Great Lakes Environmental Research Laboratory of NOAA, and now by the National Snow and Ice Data Center (NSIDC).
B. The format of the data files is as follows:
Column 1-2 blank (X2) Column 3-4 Area number (I2) Column 5-6 blank (X2) Column 7-11 Gauge number (A5) Column 12-13 blank (X2) Column 14 Latitude direction (A1) Column 15-19 Latitude (I5.2) Column 20 Filler slash (A1) Column 21 Longitude direction (A1) Column 22-26 Longitude (I5.2) Column 27-28 blank (X2) Column 29-36 Date (CCYYMMDD) (I8) Column 37-38 blank (X2) Column 39 Ice type code (A1) A = open water, no ice within vision B = solid ice, little or no signs of deterioration C = honeycombed ice, full of holes and showing evidence of deterioration D = windrowed ice, ice heaped up and frequently driven below water due to wind E = slush ice, broken or crushed ice usually extending well below surface F = drifting ice, large areas of ice which have broken off from larger fields and are drifting with the current G = ice gorge, an ice accumulation which wedges in and blocks the river X = date of first reported ice for the season Z = date of last reported ice for the season 0 = date of first or last ice observation for a season during which no ice was observed at the gauge site Column 40 number of missing reports (I1) 1 = One report missing before first reported ice or after last reported ice 2 = two reports missing before first reported ice or after last reported ice 3 = three or more reports missing before first reported ice or after last reported ice
C. A list of files in the *complete* data set is as follows:
ice_gage.txt = Documentation (this file) 1.dat = data for area 01, St. Lawrence River. 2.dat = data for area 02, Lake Ontario. 3.dat = data for area 03, Niagara River. 4.dat = data for area 04, Lake Erie. 5.dat = data for area 05, Detroit River. 6.dat = data for area 06, Lake St. Clair. 7.dat = data for area 07, St. Clair River. 8.dat = data for area 08, Lake Huron. 9.dat = data for area 09, St. Marys River. 10.dat = data for area 10, Lake Michigan. 11.dat = data for area 11, Lake Superior. extract_gage.template = example Fortran routine that can be used to extract records for a given gauge number ice_gage.tar = Unix tar' file containing the complete data set names.dat = list of area and gauge names and numbers summary_chart.dat = list of gauge locations and numbers, with reporting years summary.dat = all records for ice type = X, ice type = Z, or icetype 0, duplicated from the data files listed above. This file gives the first and last dates of reported ice for all gauge sites, for all years. summary.txt = documentation file for summary.dat
D. Examples of record format for dates of first and last reported ice:
02 2058 N43.26/W77.62 19781115 B = Solid ice on 11/15/78. 02 2058 N43.26/W77.62 19781115 X = Date of first reported ice of the season; all "A" reports before this date. 02 2058 N43.26/W77.62 19791128 F = Drifting ice on 11/28/79. 02 2058 N43.26/W77.62 19791128 X1 = Date of first reported ice of the season; there is no report for the 1 day previous. 02 2058 N43.26/W77.62 19801115 E = Slush ice on 11/15/80. 02 2058 N43.26/W77.62 19801115 X2 = Date of first reported ice of the season; there are no reports for the 2 days previous. 02 2058 N43.26/W77.62 19811231 B = Solid ice on 12/31/81. 02 2058 N43.26/W77.62 19811231 X3 = Date of first reported ice of the season; there are no reports for the 3 or more days previous. 02 2058 N43.26/W77.62 19820328 F = Floating ice on 3/28/82. 02 2058 N43.26/W77.62 19820328 Z3 = Date of last reported ice of the season; there are no reports for 3 or more days following 28 March. All reports (if any) following the 3+ day gap are "A", open water. 02 2058 N43.62/W77.62 19831101 0 = Date of first report when no ice is observed during the entire season. 02 2058 N43.26/W77.62 19840501 0 = Date of last report when no ice is observed during the entire season.
E. Water level gauge location history and explanation of gauge number/letter codes:
Several gauge locations have been changed during the time ice observations have been collected. The information given here was obtained from NOAA National Ocean Service and is as complete as possible.
F. Instructions to ice observers for recording ice conditions
Code Description ----- ----------- A Open Water, no ice within vision. B Solid Ice, little or no signs of deterioriation. C Honeycombed Ice, full of holes and showing evidence of deterioration. D Windrowed Ice, ice heaped up and frequently driven below water due to wind. E Slush Ice, broken or crushed ice usually extending well below surface. F Drifting Ice, large areas of ice which have broken off from larger fields and are drifting with the current. G Ice Gorge, an ice accumulation which wedges in and blocks the river.
G. Questions about the format or content of this data should be addressed to:
NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
Citations in reference lists accompanying published work should be stated:
National Snow and Ice Data Center. 1995. Great Lakes daily ice observations at NOAA water level gauge sites. Boulder, CO: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5PN93HT
Sharing your data with NSIDC
The International Council of Scientific Unions, in Resolution 8 of its 22nd General Assembly, recommended that "...all ICSU members support the fundamental principle of open exchange of data and information for scientific purposes." In the spirit of this resolution, NSIDC/WDC for Glaciology, Boulder encourages users of data distributed online and in other forms by NSIDC/WDC for Glaciology, Boulder to consider contributing their own published data to NSIDC/WDC for Glaciology, Boulder archive.
If you have published data that you wish to archive and make available to the scientific community, please contact NSIDC User Services to initiate a discussion of the content, form and size of the data set. A list of guidelines for submitting data in electronic form is available.