Great Lakes Regions
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Click on the region you wish to view to get the most recent ice analysis.
Due
to varying system properties, please consult your imaging software manual
for printing instructions.
++To
improve the visual quality of our weekly analysis, our files are now produced
in PDF Format. Please contact NIC Liaison
if you have any questions.++
All NIC regional sea ice, Great Lakes, and Chesapeake
Bay analyses are derived from near real-time integration of remotely sensed
and in-situ oceanographic/meteorological observations. These analyses
are produced following standard analysis procedures, which optimize the
use of data that vary widely in availability, scale, and resolution. These
operational data sources can be grouped into the following categories:
satellite-derived data, aerial ice reconnaissance, ship/shore stations
observations, drifting buoy reports, meteorological guidance products,
ice prediction model output, climatology and sea ice information obtained
from international partners such as foreign ice services. Documentation
recording the percentages of each data types used in each analysis can
be found in a weekly metadata narrative.
NIC Great Lakes analysis and forecast guidance products are
produced on regional and tactical scales. These products are disseminated
in both digital and analog formats.
GREAT LAKES CURRENT ICE SEASON PRODUCTS
The
NIC Great Lakes ice season begins on or about the 1st of December by producing
a 90 day
seasonal outlook and a 30
day forecast of ice conditions valid March 1st and January 1st respectively.
The 90 day outlook is produced once per ice season, while the 30 day forecast
is produced the 1st and 15th of every month from December to March. The
NIC also produces a five lake composite chart twice a week starting when
the first lasting ice develops on the lakes. This is usually during the
first week of December. The Great lakes ice season ends when the last observed
or analyzed ice melts, usually around the beginning of May. The dates of
starting and ending vary based on the severity of the ice year. The weekly
tactical scale analyses, which were Green Bay Duluth, Detroit/St. Clair
rivers, St. Mary’s river, and the Straits of Mackinaw, have been removed
from the NIC product suite. Tactical scale products will be produced as
needed for US. Coast Guard support in the form of annotated Radarsat images.
Images in JPEG File Interchange Format (*.jpg) will be produced for non-government
users without the Radarsat image in the background.
HISTORY
The
National Ice Center (NIC) began producing ice charts for the Great Lakes
in 1983. Prior to 1983, charts were produced by the National Weather Service.
The NIC maintains a record of NWS charts for the Great Lakes back to the
early 1970’s. Initial NIC charts analyzed yearly surface water temperatures
and winter ice cover. By 1985 NIC was responsible for analyzing the seasonal
ice in the Great Lakes. NIC charts cover all five lakes and two sub-sectors
which highlight the Detroit / St. Claire rivers and the St. Mary’s river.
The highlighted areas are key junctions between different Lakes that are
vital to commercial traffic. These areas were added to provide a more detailed
look of ice conditions for safe navigation. This format of coverage was
maintained on paper charts until the 1995-1996 ice season, at this time
the paper charts were replaced by digital charts produced on a Geographical
Information System (GIS) known as GRASS. During the following season (1996-1997)
the highlighted regions were increased in number to cover other significant
navigational problem spots. The addition of highlighted regions was made
possible by the RADARSAT satellite, which offers higher resolution imaging
capabilities.
Great Lakes Digital products include:
1. Ice analyses in JPEG File Interchange Format (*.jpg) which can be viewed
with almost any web browser and/or graphics viewer.
2. Geographical Information System (GIS) ARC/INFO coverages.
JPEG charts are labeled using the World
Meteorological Organization (WMO) international sea/freshwater ice symbology
known colloquially as the "egg
code". ARC/INFO coverages are produced in Universal Transverse Mercator
(UTM). All ARC/INFO sea ice attribute information are coded in a modified
text strings derived from the WMO digital sea ice standard known as SIGRID.
All NIC digital ice products use this attribute standard to describe analyzed
sea ice parameters.
