Dehn Ice ChartsDehn Ice Charts, 1953-1986 | ARC Archives Catalog
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Administrative/Biographical History
The National Snow and Ice Data Center houses the collection of 6,896 paper ice charts of Alaska, the western Canadian Arctic and Bering Sea covering the years 1953 through 1986. This collection was compiled by William H. Dehn and his organization, Sea Ice Consultants, Inc., and donated to NSIDC/World Data Center for Glaciology, Boulder, by his estate after his death for use by the climate and global change research community. William H. Dehn was one of the first ice observers for the U.S. Navy, flying in the 1950s on ice reconnaissance flights. The charts show location and extent of sea ice cover, charted (depending on year in the series) from aerial reconnaissance, ship observations, and satellite imagery. For 1975-1986 charts, the collection comprises the entire realtime analysis/forecast activity of Sea Ice Consultants, Inc., including detailed analyses for Alaskan and western Canadian waters.
The charts in this collection are believed to contain much unique information. Many of the charts pre-date the regular ice charting activities of the NOAA/Navy/Coast Guard National Ice Center (formerly the Navy - NOAA Joint Ice Center), which began in the 1970s. Charts predate regular satellite observations as well. Applications for the data may include research on sea ice edge position for climate studies, fisheries research, and coastal processes research. For example, hindcast studies of wind and waves in Beaufort Sea show multi-decadal variability, with many high-ranking events in the 1950s to 1970s. Ice information for this period is needed to understand interplay of ice and weather, and is potentially important in understanding Alaska coastal erosion.
In 1992 the collection was examined by Don Barnett, a colleague of William Dehn and long-time ice analyst at the Navy - NOAA Joint Ice Center and its predecessor organizations. Mr. Barnett verified the quality and importance of the collection and provided a summary that is included as a reference in this documentation. There are two main impediments to deriving useful information from the Dehn charts: the spotty nature of the drawn ice features, especially on the earlier charts in the series, and incomplete understanding of the ice analysis code or notations used.
The chart analyses were drawn on eight base maps that NSIDC has named Mackenzie Bay (MAC), Bering Strait (BS), Point Barrow (B), Bering Sea (BER), Bering Sea East (BSE), Bering Sea West (BSW), Beaufort Sea (BFT), and Chukchi Sea (CHK).
Author: Florence Fetterer, Allaina Wallace Administrative Information
The National Snow and Ice Data Center/World Data Center for Glaciology, Boulder (NSIDC/WDC) holds a collection of charts depicting ice conditions in the seas off Alaska and western Canada coasts. Ice edge position and some ice concentration and other information are included, though the notations on the charts are often sparse and discontinuous in space and time, especially for older charts in the series.
The earliest chart is from January 1953, and the most recent is from December 1986. They range in number from about 80 to about 350 per year. A major change occurred in 1975, when the number of analyses roughly doubled. From 1975 on, Sea Ice Consultants, Inc. provided near real time analyses and forecasts. Charts from this period are extremely detailed and are believed to be the best available for Alaskan waters.
