CONUS (Great Lakes, Chesapeake Bay, and Delaware
Bay Regions)
Click
on the Lake or Bay you wish to view to get the most recent
ice analysis. To view the most recent black
and white ice analysis for the Chesapeake Bay, Delaware Bay,
Potomac River, and C and D Canal, please click on the "Chesapeake
and Delaware Bay Products" drop down menu. To view products
from past seasons for the Great Lakes, please click on the "Archive" drop
down menu. To view products from past seasons for the Chesapeake
Bay, Delaware Bay, Potomac River, and C and D Canal, please
click on the "Chesapeake and Delaware Bay Products" drop
down menu. 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.++
GREAT LAKES PRODUCT GENERATION
Tuesday's composites analyzed by
the Canadian Ice Center (CIS)
(Naming convention: cisyymmdd yy=year mm=month dd=day)
Friday's composites analyzed by the National Ice Center (NIC)
(Naming
convention: elyymmdd Eastern Great Lakes)
(Naming convention: wlyymmdd Western Great Lakes)
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.
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.
Clair 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 and Chesapeake Bay Digital products include:
1. Ice analyses in Portable Data Format (*.pdf) which can be
viewed with almost any web browser and/or graphics viewer.
2. Geographical Information System (GIS) ARC/INFO coverages.
Ice 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.
