waves, impacting a coral reef. Internal wave packets, propagating toward the west,
refract around the Dongsha coral atoll, a national park located in the South China
Sea (Zhao et al. 2008). These waves have been measured and determined to have
amplitudes exceeding 50 m. Cold water intrusions resulting from these waves can
lead to temperature decreases of 8 °C, variations in dissolved oxygen, and
increases in chlorophyll concentration, all of which can significantly impact the
coral reef ecosystem (Wang et al. 2007).
Waves Coastal wave information is useful for safety of recreational and commercial boating and fishing, coastal barge and ferry transportation, and activities
such as surfing, diving and ecotourism. For coral reef management, information on
the distribution and intensity of waves is important for monitoring mechanical
wave action during bleaching events or destructive storms. Figure 13.12 depicts an
experimental swell wave product generated from a RADARSAT-1 Single Look
Complex (SLC) image showing swell wave variations in the Alenuihaha Channel
between the Hawaiian islands of Maui and Hawaii. SLC images contain both
amplitude and phase information needed by the wave algorithm. This twodimensional depiction of the wave field provides valuable information regarding
coastal changes in wave height, wavelength, and wave direction. In this case, the
maximum swell significant wave height is about 3 m in the channel. While there
are no ocean wave buoys in the region shown by the image to corroborate this
estimate, an open ocean buoy, 51202, located to the west of this image at 21.417°N
and 157.608°W reported a significant wave height of 3.8 m at 16:00 UT on this
day (buoy data are available from the NOAA National Data Buoy Center:
www.ndbc.noaa.gov).
Vessel monitoring Vessel impacts to coral reefs include destruction of coral
from anchoring or running aground, introduction of invasive species, and marine
pollution from oil or other chemical releases (Franklin 2008). Although at the
present time obtaining SAR imagery with sufficient frequency to continuously
monitor ship traffic in coral reef management areas is prohibitively expensive, it
can be used to spot check AIS non-compliance, as well as to periodically monitor
sensitive and restricted regions. For example, Fig. 13.13 indicates the presence of
a ship within the Papaha ¯naumokua ¯kea Marine National Monument, a 1,530 km
long chain of coral atolls and islands stretching northwest of the main Hawaiian
Islands. Monitoring ship traffic within the Monument is important to enforce
areas closed to fishing and boating, as well as to monitor ship traffic and possible
oil spills from vessels sailing along the island chain or transiting the shipping
corridor that cuts through the Monument between Pearl and Hermes Atoll and
Lisianski Island (Franklin 2008). Linking of slicks and vessel targets provides
insight as to whether a slick might be an intentional release of oil or a natural
surfactant slick.
13 Radar Applications
361
refract around the Dongsha coral atoll, a national park located in the South China
Sea (Zhao et al. 2008). These waves have been measured and determined to have
amplitudes exceeding 50 m. Cold water intrusions resulting from these waves can
lead to temperature decreases of 8 °C, variations in dissolved oxygen, and
increases in chlorophyll concentration, all of which can significantly impact the
coral reef ecosystem (Wang et al. 2007).
Waves Coastal wave information is useful for safety of recreational and commercial boating and fishing, coastal barge and ferry transportation, and activities
such as surfing, diving and ecotourism. For coral reef management, information on
the distribution and intensity of waves is important for monitoring mechanical
wave action during bleaching events or destructive storms. Figure 13.12 depicts an
experimental swell wave product generated from a RADARSAT-1 Single Look
Complex (SLC) image showing swell wave variations in the Alenuihaha Channel
between the Hawaiian islands of Maui and Hawaii. SLC images contain both
amplitude and phase information needed by the wave algorithm. This twodimensional depiction of the wave field provides valuable information regarding
coastal changes in wave height, wavelength, and wave direction. In this case, the
maximum swell significant wave height is about 3 m in the channel. While there
are no ocean wave buoys in the region shown by the image to corroborate this
estimate, an open ocean buoy, 51202, located to the west of this image at 21.417°N
and 157.608°W reported a significant wave height of 3.8 m at 16:00 UT on this
day (buoy data are available from the NOAA National Data Buoy Center:
www.ndbc.noaa.gov).
Vessel monitoring Vessel impacts to coral reefs include destruction of coral
from anchoring or running aground, introduction of invasive species, and marine
pollution from oil or other chemical releases (Franklin 2008). Although at the
present time obtaining SAR imagery with sufficient frequency to continuously
monitor ship traffic in coral reef management areas is prohibitively expensive, it
can be used to spot check AIS non-compliance, as well as to periodically monitor
sensitive and restricted regions. For example, Fig. 13.13 indicates the presence of
a ship within the Papaha ¯naumokua ¯kea Marine National Monument, a 1,530 km
long chain of coral atolls and islands stretching northwest of the main Hawaiian
Islands. Monitoring ship traffic within the Monument is important to enforce
areas closed to fishing and boating, as well as to monitor ship traffic and possible
oil spills from vessels sailing along the island chain or transiting the shipping
corridor that cuts through the Monument between Pearl and Hermes Atoll and
Lisianski Island (Franklin 2008). Linking of slicks and vessel targets provides
insight as to whether a slick might be an intentional release of oil or a natural
surfactant slick.
13 Radar Applications
361