Data consist of ice observations from U.S. Coast Guard vessels operating on the Great Lakes, and from Coast Guard shore stations reported via teletype messages and ice logging forms. Observations include ice thickness and concentration, weather conditions, and ice breaking activity. Data from 1961/1962 through 1966/1967 have been processed to a standard format and sorted by year and stations, and are available via FTP as ASCII files, one for each of the five lakes. These data were provided to NSIDC by the NOAA Great Lakes Environmental Research Laboratory (GLERL), along with documentation. The documentation, Great Lakes Environmental Research Laboratory Great Lakes Surface Ice Reports, 1961-1966, is included here. Data from 1970/1971 through 1993/1994 are available on microfilm. The original ice reporting forms for these years were filed as part of the ice operations files of the Ninth District U.S. Coast Guard Ice Navigation Center, Cleveland, OH. Data from 1994/1995 through 2003/2004 are available via FTP in a single .tar file for each ice season.
Note that no editing or quality control has been performed on this data set. Microfilmed records are difficult to use, as they are sorted by date and time only, and contain extraneous information. The electronic data from 1994/1995 forward are raw teletype reports. These are not in a consistent format, and also contain extraneous information. NSIDC obtained these data from a NOAA National Weather Service public FTP server. The National Weather Service obtained the data from the United States Coast Guard Headquarters. NSIDC was unable to locate a responsible party within NOAA who could provide NSIDC with a new source for the data. Therefore, the records end in 2004. Users may wish to contact the U.S. Coast Guard for information on obtaining the individual ship reports.
National Snow and Ice Data Center, compiler. 1995. Great Lakes surface ice reports from U.S. Coast Guard. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5BG2KW2
As a condition of using this data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.
|Data Format||ASCII, microfilm|
|Spatial coverage and resolution||Great Lakes region|
|Temporal coverage and resolution||1961-2004|
|File size||The digital portion of the data set is 5.99 Mb.|
Ice thickness, ice extent, maximum/minimum temperature
|Metadata access||View metadata|
|Data access||Data are available via FTP.|
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
Data consist of visual ice observations from U.S. Coast Guard vessels operating on the Great Lakes, and from Coast Guard shore stations reported via teletype messages and ice logging forms. Observations include ice thickness and concentration, weather conditions, and ice breaking activity.
Data from 1961/1962 through 1966/1967 have been processed to a standard format and sorted by year and stations, and are available via FTP as *.dat files, one for each of the five lakes. These data were provided to NSIDC by the Great Lakes Environmental Research Laboratory, along with documentation. The documentation, Great Lakes Environmental Research Laboratory (GLERL) Great Lakes Surface Ice Reports, 1961-1966, is reproduced below (in Detailed Data Description) in slightly edited form.
Teletype ice reports and weekly ice observation logs, from 1970/1971 irregularly through 1993/1994, are available on microfilm as follows (note gaps in 1878/1979, 1984/1985, and 1990/1991):
Data from 1970/1971 through 1977/1978 are available on 14 reels of 16mm microfilm. These 14 reels contain, in addition to ice conditions and meteorological observations, the Great Lakes ice operations files for the Ninth District U.S. Coast Guard Ice Navigation Center, Cleveland, OH. There is an index to the approximate film location of the surface ice reports (GLERL-1 through GLERL-14).
Data from 1979/80 through 1982/83 are available on 1 reel of 16mm microfilm (GLERL-15).
Data for 1980/81 exclusively are available on 1 reel of 16mm microfilm (GLERL-41).
Data for 1983/84 exclusively are available on 1 reel of 16mm microfilm (GLERL-44).
Data for 1991/92 through 1993/94 are available on 1 reel of 16mm microfilm (GLERL-46).
Data from 1994/1995 through the last ice season are available via ftp as .tar files for each ice season. These ice files are in the raw native format used by the USCG (i.e. teletype message format). These data have not been quality checked in any way at NSIDC and are provided to the user only in this raw form.
No Coast Guard shore station reports are available after 1991.
The information that follows is from documentation provided to NSIDC by Dr. Raymond A. Assel. It pertains to the 1961 to 1967 data that were given to NSIDC by Dr. Assel. The documentation provided by Dr. Assel has been reformatted but is otherwise unchanged.
The original data file from GLERL was split at NSIDC into five files corresponding to each of the Great Lakes. Lake St. Clair is included in the erie.dat file. The straits of Mackinac, following the convention from the station directory, are included in the huron.dat file.
No data on wind speed, wind direction, cloud type, cloud concentration, lake ice thickness, snow ice thickness, or slush thickness exist in the data file. These measurements were not recorded before the 1973-1974 ice season. These columns exist within the data files but are blank.
The convention -99 is used as an indicator for missing data.
The given location of the observation was checked against the list of stations in the Great Lakes Hydrometeorological Station Directory, NOAA data report ERL GLERL-22, Feb. 1983 and the list of Coast Guard stations in the United States Coast Pilot #6, Great Lakes, April 1982, U.S. Department of Commerce, NOAA. The ice reports were taken by both shore stations and ship reports. There is no factor which allows the user to tell from which observing platform each observation came from. A list of the U.S. Coast Guard stations within the Great Lakes is included, as are some selected Coast Guard light station locations. Many of the locations of observations map to known Coast Guard station locations, however some do not and the validity of long term measurements from these sites should be suspect. See Appendix A for the list of stations.
The following data is contained within each file of Great Lakes Surface Ice reports:
|Season||The winter season of the data reports.|
|Location||The location of the USCG data station.|
|Month||The month of the data report.|
|Day||The day of the data report.|
A term describing the size of the ice and if the ice is attached to the shore. Up to three ice types can be given to more fully describe the ice. See Appendix B for description of the ice types.
|Age||A term describing the stage of melting or thickness of the ice cover. See Appendix C for description of the ice age terms.|
|Surface||The surface condition of the ice. See Appendix D for list of definitions.|
|TI||Ice thickness in inches.|
|LI||Lake Ice thickness in inches (empty field).|
|SI||Snow Ice thickness in inches (empty field).|
|SL||Slush thickness in inches (empty field).|
|SN||Thickness of snow cover on the ice in inches.|
|CONC||The percent of total observed water surface area that is covered by ice.|
|NAVIG||A description of the type of navigation possible given the reported ice conditions. See Appendix E for definitions of terms.|
|HI||Maximum air temperature in degrees Fahrenheit recorded during the previous 24 hours.|
|LO||Minimum air temperature in degrees Fahrenheit recorded during the previous 24 hours.|
|The remaining fields; WS, WD, CT, and CC, are all empty as this data was not recorded until the winter of 1973-1974.|
|Alexandria Bay||44-19.9N 75-56.1W|
|Sodus Bay||43-16.4N 76-58.5W|
|Youngstown, Niagara R.||43-15.7N 79-03.8W|
|Cape Vincent LTSTA||44-07N 76-20W|
|Tibbets Point LTSTA||44-06N 76-22W|
|Detroit, Belle Is.||42-20.4N 82-57.7W *Detroit River|
|St. Clair Shores||42-28.4N 82-52.8W *Lake St. Clair|
|St. Clair Flats||42-33.1N 82-39.0W *St. Clair River|
|Port Huron||43-00.3N 82-25.3W|
|Harbor Beach||43-51.0N 82-38.6W|
|Saginaw River||43-38.1N 83-51.0W|
|East Tawas||44-15.3N 83-26.2W|
|St. Ignace||45-51.3N 84-42.2W *near Mackinac Straits|
|Thunder Bay LTSTA||45-02N 83-12W|
|Grand Haven||43-03.6N 86-14.8W|
|St. Joseph||42-06.8N 86-29.1W|
|Michigan City||41-43.4N 86-56.4W *near Indiana Harbor|
|Calumet Harbor||41-43.0N 87-31.6W|
|Two Rivers||44-08.8N 87-33.7W|
|Sturgeon Bay||44-47.7N 87-18.7W|
|Green Bay||44-32.2N 88-00.2W|
|Beaver Island LBSTA||45-45N 85-30W|
|Sault Ste. Marie||46-30.0N 84-20.3W|
|Grand Marais||46-40.6N 85-58.4W|
|Keweenaw Waterway||47-13.5N 88-37.4W|
|Whitefish Point LTSTA||46-46N 84-57W|
|North Manitou LTSTA||45-01N 85-57W|
|Appendix B - Ice Type Terms|
||An area of pack ice consisting of any size of floes which is greater than ten kilometers across.|
|PANCAK||Predominantly circular pieces of newly formed ice from three meters in diameter, and up to nine centimeters in thickness, with raised rims due to collisions.|
|FLOE||Any relatively flat piece of ice ten meters or more across. A floe may consist of a single unbroken fragment or many consolidated fragments.|
|CAKE||Any relatively flat piece of ice less than ten meters across. Cake implies a single unbroken fragment of ice.|
|BRASH||Accumulations of floating ice made up of fragments not more than 2 meters across, the wreckage of other forms of ice.|
|SLUSH||Snow which is saturated and mixed with water, a viscous floating mass in water after a heavy snowfall. It is an accumulation of ice crystals which may or may not be slightly frozen together. Slush has no degree of hardness.|
|FAST/SHORE||Stretches of unbroken ice which are fast to the shore.|
|Appendix C - Ice age terms|
||Fairly level, flat sheet of clear ice, blue appearance, may be fast.|
|WHITE||First stage of thawing or ice formed largely of snow.|
|ROTTEN||Honeycombed due to melting-needle ice.|
|Appendix D - Ice Surface Conditions|
||Ice which has been pressed into heavy ridges or layers by strong winds, often piled up against the shore or other obstruction.|
|JAMMED||(1) An accumulation of broken river ice in a narrow channel. (2) Fields of lake ice separated from the shores in early spring may be blown against the shore, exerting great pressures. Also, masses of broken-up ice may drift with the wind and produce jams on and against the shore.|
|Appendix E - Navigation Terms|
||From the Coast Guard documentation it is unclear whether this refers to Closed Craft, when navigation closed to small craft and craft with poor icebreaking hulls, or Closed, when all navigation is closed.|
|DIFF||Navigation possible by large vessels with fair to good icebreaking hull configurations. HP/L ratio less than 6:1.|
|STEAMR||This flag is undocumented within the Coast Guard documentation. The flag may refer to navigation only possible by large vessels constructed to withstand ice pressure and with fair to good icebreaking hull configurations. HP/L ratio 6:1 or greater.|
|ICEBKR||Navigation only possible with the assistance of icebreakers.|
1 USCG ICE REPORTS BY STATION: 1962-63 ASHTABULA " ----------------------------------------------------------------------------------------------- MO DA ICE TYPES AGE SURF TI LI SI SL SN C NAVIG HI LO WS WD CT CC " ----------------------------------------------------------------------------------------------- 12 15 SLUSH WHITE 0 0 0 UNOBST -99 -99 12 16 FAST PANCAK WHITE JAMMED 2 1 8 UNOBST 38 18 12 17 FAST FIELD ROTTEN 2 0 7 UNOBST 24 10 12 18 0 0 0 UNOBST -99 -99 12 19 0 0 0 UNOBST 52 20 12 20 0 0 0 UNOBST 44 26 12 22 FAST PANCAK WHITE JAMMED 3 0 10 CLOSED 31 18 12 23 DRIFT PANCAK ROTTEN 2 3 5 UNOBST 33 15 12 24 DRIFT PANCAK WHITE 1 1 1 UNOBST 27 16 12 25 FAST PANCAK WHITE 2 0 3 UNOBST 23 11
Assel, R. A. Great Lakes weekly ice cover statistics. NOAA Technical Memorandum GLERL-133. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 27 pp. (2005). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-133/
Assel, R. A. Computerized National Weather Service Great Lakes ice reports for winter seasons 1899-1970. NOAA Technical Memorandum GLERL-130. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 31 pp. (2004). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-130/
Assel, R. A. A Laurentian Great Lakes ice cover climatology. Proceedings of the 61st Annual Meeting of the Eastern Snow Conference, Portland, Maine, June 9-11, 2004. 2 pp. (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040027.pdf
Assel, R. A., F. H. Quinn, and C. E. Sellinger. Hydro-climatic factors of the recent drop in Laurentian Great Lakes water levels. Bulletin of the American Meteorological Society 85(8):1143-1151 (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040017.pdf
Assel, R. A., S. Drobot, and T. E. Croley, II. Improving 30-day Great Lakes ice cover outlooks. Journal of Hydrometeorology 5(4):713-717 (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040016.pdf
Assel, R. A., S. Drobot, and T. E. CROLEY, II. Improving monthly Great Lakes ice cover outlooks. NOAA Technical Memorandum GLERL-129. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 22 pp. (2004). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-129/
Assel, R. A. Lake Erie ice cover climatology -- basin averaged ice cover: winters 1898-2002. NOAA Technical Memorandum GLERL-128. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 15 pp. (2004). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-128/
US Coast Guard Ninth District Operation Plan 1 FY Annex X
Great Lakes Hydrometeorological Station Directory, NOAA data report ERL GLERL-22, Feb. 1983
US Coast Pilot #6; Great Lakes, April 82, US Department of Commerce, NOAA
Dr. Raymond A. Assel, NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, provided NSIDC with the data for 1961-1967, and with documentation for the data. This data set is maintained at NSIDC with support from the NOAA National Geophysical Data Center.
The information in Detailed Data Description was authored by Dr. Raymond A. Assel, GLERL. The original author of the documentation at NSIDC is unknown.
Jason Wolfe revised this document in October 1998 based on a review of NSIDC's data holdings. The document was edited again in July 2006 by Florence Fetterer to state why the data were no longer being updated. At this time the document was reformatted.