Monthly Average Ice Cover Metadata ================================== File Names for monthly averaged ice cover for the 105 winters: 1898-2002 ------------------------------------------------------------------------ dec.txt - for December jan.txt - for January feb.txt - for February mar.txt - for March apr.txt - for April ------------------- These files contain ------------------- 1. modeled data for winters 1898-1972 2. Canadian Ice Service data for winters 1973-1988 3. National Ice Center data for winters 1996-2002 4. An average of CIS and NIC data, based on daily data, for winters 1989-1995 ---------------------------------------------------------------------------- If the user wants the original cis and nice files for winters 1989-1995 they are available as well in the following files: ---------------------------------------------------------------------------- cec-cis.txt - Canadian Ice Service ice data for December jan-cis.txt - Canadian Ice Service ice data for January feb-cis.txt - Canadian Ice Service ice data for February mar-cis.txt - Canadian Ice Service ice data for March apr-cis.txt - Canadian Ice Service ice data for April dec-nic.txt - National Ice Center ice data for December jan-nic.txt - National Ice Center ice data for January feb-nic.txt - National Ice Center ice data for February mar-nic.txt - National Ice Center ice data for March apr-nic.txt - National Ice Center ice data for April ------------------------------------------------------------------------------ There is one record for each winter season in each of the files listed above. ------------------------------------------------------------------------------ Record Format:(i5,4(1x,f5.1)) ----------------------------- Information in each record -------------------------- field 1. winter season field 2. monthly average L. Erie ice concentration field 3. monthly average west basin ice concentration field 4. monthly average center basin ice concentration field 5. monthly average east basin ice concentration -------------------- Units of measurement -------------------- Monthly spatial average ice concentration for a given winter expressed as a percent of the surface area covered by ice. Ice Code for missing data: -1.0 If a month had less than 25 days of data the code for missing data was entered for that month. ------------------------------------------------------------------------------------ Modeled data are based on information abstracted from Assel (1990). Observed data were calculated from data on daily ice cover grids given in Assel (2003). Assel, R.A., 1990. An ice-cover climatology for Lake Erie and Lake Superior for the winter seasons 1897-98 to 1982-83, International Journal of Climatology, 10:731-748. Assel, R.A., 2003. NOAA Atlas, An Electronic Atlas of Great Lakes Ice Cover winters 1972-2003. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, Michigan 48105. Data Set Created December 2003 ------------------------------ Raymond Assel NOAA/GLERL 4840 S. State Rd. Ann Arbor, MI email: Ray.Assel@noaa.gov