202
10.1
Introduction
C. BERTOIA, J. FALKINGHAM, F. FETTERER
Many polar nations, including Canada, the United States, Russia, and the Baltic countries, support shipping and other maritime activities in ice-encumbered waters. Visual reconnaissance from aircraft was initially used to map sea ice distribution but this
method suffered from extremely limited range and subjective interpretation techniques. Imaging radar became available in the early 1970S when real aperture side-looking airborne radars (SLAR) were deployed to complement and extend the range oftraditional visual observations. Canada was the first nation to routinely deploy synthetic
aperture radar (SAR) for operational ice surveillance when it commissioned an X-Band
SAR on a high-flying jet aircraft. The European Space Agency's ERS-l was the first satellite to provide SAR data on a sufficiently regular basis for operational ice surveillance.
Canada's RADARSAT was specifically designed with operational ice surveillance as one
of its major objectives.
Within the operational community to date, SAR has mainly been used as an imaging
tool. The images created from the SAR data have been interpreted manually by human
analysts to create maps portraying the distribution of sea ice concentration, type and
floe size. The data volumes that will be provided by RADARSAT, however, will preclude
sole reliance on manual techniques. Close cooperation with the science community has
led to the development of several ice classification and ice motion algorithms suitable
for operational implementation.
10.2
Operational Requirements for Ice Information
The presence of sea ice affects virtually every aspect of Arctic operations. Since the earliest days of Arctic exploration, sea ice has affected the ability of a ship to easily reach
its destination. A captain's ice product requirements vary with the ship's ice operating
capabilities or limitations. Though accurate spatial depiction of ice conditions is
important to the mariner, temporal accuracy is of much greater importance. Generally, a ship's captain requires interpreted rather than raw images, since expert ice interpreters are found at the various national ice centers and generally not aboard ships.
The challenge to the ice centers is to process the raw data, interpret it, and disseminate
ice products to their customers within 3-12 h of data acquisition. Captains of non-icestrengthened vessels require ice edge and iceberg limit information in order to plan
their routes to avoid all known ice. Captains of vessels with some degree of ice capability require information detailing ice thickness and its associated concentration distribution. Even the most capable icebreakers use information on leads and polynyas to
choose the path of least resistance in order to achieve greatest fuel economy.
In order to effectively describe the sea ice cover, nations with Arctic interests have
developed a set of common terminology to describe the nature of sea ice and its behavior. The first compendium of internationally accepted ice terminology and symbology
was developed by representatives from the USA, USSR, Federal Republic of Germany,
and Denmark. A much broader collection of terms was compiled as interest in Arctic
operations and exploration increased; this set of revised and expanded terminology
was adopted by the World Meteorological Organization in 1968. This terminology was
10.1
Introduction
C. BERTOIA, J. FALKINGHAM, F. FETTERER
Many polar nations, including Canada, the United States, Russia, and the Baltic countries, support shipping and other maritime activities in ice-encumbered waters. Visual reconnaissance from aircraft was initially used to map sea ice distribution but this
method suffered from extremely limited range and subjective interpretation techniques. Imaging radar became available in the early 1970S when real aperture side-looking airborne radars (SLAR) were deployed to complement and extend the range oftraditional visual observations. Canada was the first nation to routinely deploy synthetic
aperture radar (SAR) for operational ice surveillance when it commissioned an X-Band
SAR on a high-flying jet aircraft. The European Space Agency's ERS-l was the first satellite to provide SAR data on a sufficiently regular basis for operational ice surveillance.
Canada's RADARSAT was specifically designed with operational ice surveillance as one
of its major objectives.
Within the operational community to date, SAR has mainly been used as an imaging
tool. The images created from the SAR data have been interpreted manually by human
analysts to create maps portraying the distribution of sea ice concentration, type and
floe size. The data volumes that will be provided by RADARSAT, however, will preclude
sole reliance on manual techniques. Close cooperation with the science community has
led to the development of several ice classification and ice motion algorithms suitable
for operational implementation.
10.2
Operational Requirements for Ice Information
The presence of sea ice affects virtually every aspect of Arctic operations. Since the earliest days of Arctic exploration, sea ice has affected the ability of a ship to easily reach
its destination. A captain's ice product requirements vary with the ship's ice operating
capabilities or limitations. Though accurate spatial depiction of ice conditions is
important to the mariner, temporal accuracy is of much greater importance. Generally, a ship's captain requires interpreted rather than raw images, since expert ice interpreters are found at the various national ice centers and generally not aboard ships.
The challenge to the ice centers is to process the raw data, interpret it, and disseminate
ice products to their customers within 3-12 h of data acquisition. Captains of non-icestrengthened vessels require ice edge and iceberg limit information in order to plan
their routes to avoid all known ice. Captains of vessels with some degree of ice capability require information detailing ice thickness and its associated concentration distribution. Even the most capable icebreakers use information on leads and polynyas to
choose the path of least resistance in order to achieve greatest fuel economy.
In order to effectively describe the sea ice cover, nations with Arctic interests have
developed a set of common terminology to describe the nature of sea ice and its behavior. The first compendium of internationally accepted ice terminology and symbology
was developed by representatives from the USA, USSR, Federal Republic of Germany,
and Denmark. A much broader collection of terms was compiled as interest in Arctic
operations and exploration increased; this set of revised and expanded terminology
was adopted by the World Meteorological Organization in 1968. This terminology was