Great Lakes Ice Climatology Update: Winter 2006-2011. Description of the Digital Ice Cover Dataset.

摘要

A 6-winter digital ice cover data set consisting of 389 ice charts of total ice concentration (the fraction of a unit of surface area covered by ice), was downloaded from the National Ice Center (NIC) website, http://www.natice. noaa.gov/products/ great-lakes.html. This report updates GLERLs 33-winter ice climatology dataset for total ice concentration (Assel 2003, Assel 2005). Data processing and quality control procedures, file structure, format, and naming conventions are described. The data are available as fixed formatted ASCII grids (2.55 km for winter 2006 and 1.275 km for winters 2007-2011) and has been converted to ArcMap feature classes for GIS users. Temporal distributionof the ice charts is summarized in tables. A planned companion report will contain an analysis of these data including spatial patterns of dates of first ice, last ice, ice duration, and ice concentration anomalies (relative to a 30-winter (1973-2002) base period) for each lake by winter season. It will also contain lake averages of total ice cover concentration that portray the seasonal progression of ice cover each winter. Since the last updated ice atlas (Assel 2005), there has been significant change in ice cover on the Great Lakes. This update of the ice atlas should be useful to the research community as well as others who rely on Great Lakes ice data for planning purposes. The technical memorandum that updated the ice atlas for winters 2003, 2004, and 2005 (Assel 2005) did not include ArcGIS feature classes, so those are included here.