Ice Observations, 1955/56 to 1996/97 at NOAA/NOS Great Lakes Water Level Gauge Sites

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).

The data are available via FTP and you can also view the Metadata.

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.

  1. Gauge number 1060, Alexandria Bay, was moved across the river in June 1983. NOAA/NOS changed its number to 1062, the data set retains the number 1060.
  2. Gauge number 4090, Mouth of the Black River, Port Huron, Michigan, has two reports for some years. 4090A is the Black River itself, 4090B is the St. Clair River.
  3. Gauge number 4098, Ft. Gratiot, has two reports for some years. 4098A is the lake above the gauge site, 4098B is the river below the gauge site.
  4. Gauge number 5098, Detour, was moved one-half mile to Detour Village in November 1977. NOAA/NOS changed the gauge number to 5099, the data set retains the number 5098.
  5. Gauge number 7078, Green Bay, had a new containment building constructed in September 1979. NOAA/NOS changed the gauge number to 7079, the data set retains the number 7078.
  6. Gauge number 9016, Marquette, was moved one-quarter to one-half mile in January 1980 and NOAA/NOS changed its number to 9018. The data set retains the number 9016.
  7. Gauge number 9064, Duluth, has several reports for most years. Through 1980/81, the observations are: 9064 = gauge site; 9064A = canal toward harbor; 9064B = canal; 9064C = canal toward lake. Beginning with 1980/81, the observations are: 9064A = into harbor; 9064B = canal; 9064C = lakeward.
  8. Gauge number 6060, U.S. Slip, has multiple observations for some years. the codes are: 6060 = below the locks; 6060A = inside the lock approach; 6060B = from lock to Topsail Island; 6060C = below the locks.

F. Instructions to ice observers for recording ice conditions

  1. Ice records are to be prepared by water level gauge observers during the cold weather season beginning on 1 November of each year and continuing through 30 April of the following year. The records will contain daily observations of ice conditions at the locations specified in the observers' contracts according to the instructions provided in paragraph 2, below, recorded on the calendar page forms provided by the National Snow and Ice Data Center, Boulder, Colorado.
  2. On each day beginning 1 November and continuing through 30 April, record on the corresponding calendar date space a letter code indicating the ice condition, and any appropriate comments. The following tabulation shows the letter code to be used:
    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.
    
  3. Use a single letter "A" if no ice is observed for that day. Use the appropriate single letter code if there is a single, uniform ice condition at the time of observation. Two or more codes may be used when two or more ice conditions are present at the time of the observation. Short additional comments may be added if necessary to clarify the use of two or more codes.

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
e-mail: nsidc@nsidc.org

H. Citations

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.