The National/Naval Ice Center (NIC) has concluded that the 2009 sea ice minimum occurred between the 16th and 23rd of September, 2009. The NIC is an operational command, and monitors all known sea ice, regardless of concentration and/or ice type in the evaluation of ice extent. According to available NIC data sources and analysis, the lowest extent of 2009 was estimated to have covered 5.84 million square kilometers.
NIC analysts produce a daily ice edge using a variety of imagery sources ranging from 100 meter to 12km resolution. It is from this daily ice edge that the total sea ice extent is calculated. Because the NIC uses a variety of data sources and includes all known ice including areas of water surrounding the ice, NIC sea ice extent numbers are generally higher than organizations using passive microwave imagery sources or applying lower resolutions.
As a joint interagency organization of the U.S. Navy, National Oceanic and Atmospheric Administration (NOAA), and U.S. Coast Guard, the NIC runs NOAA’s Interactive Multi-sensor Snow and Ice Mapping System (IMS). Relatively new to the NIC, this system also applies multiple source (Visible sensors, Passive Microwave instruments, Scatterometry instruments, Synthetic Aperture Radar) imagery, and Ship Observations, but produces an ice edge product with a constant resolution of 4km. Because of this constant resolution, the IMS product is presently used as an operational input into several NWS computer weather prediction models as well as several other governmental agencies.
Data from IMS estimated the 2009 sea ice minimum to have covered 4.88 million square kilometers. IMS does not include areas of water surrounding ice in its calculation, so the number represents area covered by ice rather than total extent. This figure closely mirrors NIC’s 100% ice boundary (8/10ths or more sea ice), estimated at 4.6 million square km.
The National Ice Center is a tri-agency operational center represented by the United States Navy (Department of Defense), the National Oceanic and Atmospheric Administration (Department of Commerce), and the United States Coast Guard (Department of Homeland Security). The National Ice Center mission is to provide the highest quality strategic and tactical ice services tailored to meet the operational requirements of U.S. national interests and to provide specialized meteorological and oceanographic services to United States government agencies.
For more information, please contact:
National Ice Center
Naval Ice Center
Liaison Branch
Voice: 301-394-3100
E-mail: National Ice Center Liaison
