Annual Average Ice Cover Metadata ================================= File ann1898-2002.txt covers the 105 winters 1898-2002 and it contains ---------------------------------------------------------------------- 1. modeled data for winters 1898-1972 2. Canadian Ice Service (CIS) data for winters 1973-1988 3. National Ice Center data (NIC) 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 nic files for winters 1989-1995 they are available as well in cis-ann.txt and nic-ann.txt. File cis-ann.txt contains original cis data for winters 1989-1995 File nic-ann.txt contains original nic data for winters 1989-1995 ------------------------------------- Record Format:(i5,4(2x,f8.1,1x,f5.1)) ------------------------------------- Information in each record -------------------------- field 1. winter season field 2. the sum of L. Erie daily average ice cover for a given winter field 3. the sum of L. Erie average daily ice cover for the winter divided total number of days (182) in a winter season 182. field 4. same as field 2 except for west basin of lake field 5. same as field 3 except for west basin of lake field 6. same as field 2 except for center basin of lake field 7. same as field 3 except for center basin of lake field 8. same as field 2 except for east basin of lake field 9. same as field 3 except for east basin of lake ------------------------------ Number of records in each file ------------------------------ Ann1898-2002.txt 105 cis-ann.txt 7 nic-ann.txt 7 -------------------- Units of measurement -------------------- Daily spatial average ice concentration for a given winter expressed as a percent of the surface area covered by ice. ------------------------------------------------------------------------------------ Note on modeled ice cover data ------------------------------------------------------------------------------------ These data are based on information from Assel (1990): An ice-cover climatology for Lake Erie and Lake Superior for the winter seasons 1897-98 to 1982-83, published in International Journal of Climatology, 10:731-748. ------------------------------------------------------------------------------------------------- Note on observed cis and nic data ------------------------------------------------------------------------------------------------- These data were based on daily ice cover grids given in Assel (2003): NOAA Atlas, An Electronic Atlas of Great Lakes Ice Cover: Winters 1973-2002. Great Lakes Environmental Research Laboratory, Ann Arbor, MI. ------------------------------ Data Set Created December 2003 ------------------------------ Raymond Assel NOAA/GLERL 4840 S. State Rd. Ann Arbor, MI email: Ray.Assel@noaa.gov