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R. Romeiser et al.
optimised ATI satellites for ocean applications could permit vector current measurements at an effective spatial resolution of 100 m and with improved spatial and
temporal sampling characteristics. The technology for such instruments is readily
available. Further development in this field must be driven by user demand and
should include dedicated validation campaigns. In the following we discuss promising applications. Some text and figures have been adapted from Romeiser and Runge
(2008).
5.4.1 Global Oceanography
Chapron et al. (2005) have demonstrated the generation of global surface current
maps at a spatial resolution on the order of 100 km from ENVISAT ASAR Wave
Mode data. Johannessen et al. (2008) have shown that ASAR Wide Swath data
can reveal large surface currents of the Agulhas Current that are not detected by
altimeters.
Both capabilities can be very useful for global circulation studies as well as for
studies on the dynamics of strong mesoscale current features in certain areas. The
potential spatial resolution improvement of the ATI technique by more than one
order of magnitude can be useful for studies on small-scale current features that have
a strong larger-scale effect on the upper-ocean circulation as well as on chemical and
biological processes.
For example, McGillicuddy et al. (2007) describe a stimulation of mid-ocean
plankton blooms by eddy/wind interactions. Some of the eddies of interest can be
seen in altimeter data, but an analysis of high-resolution current fields from singleantenna Doppler anomaly or ATI measurements, ideally in combination with water
colour and temperature data from other sensors, would be highly desirable for more
detailed investigations and improved model developments in this field.
5.4.2 Coastal Oceanography
The general circulation patterns in coastal seas are often well known and reproducible by numerical circulation models. Furthermore, many HF radars have been
installed within the last decade for a continuous monitoring of currents, waves,
and ship traffic in coastal regions (e.g. Gurgel and Schlick, 2007). However, quasigeostrophic dynamic processes on spatial scales of 1–10 km are still not entirely
understood, and they may be of interest for scientists and other users who are
unable to install coast-based remote sensing systems or to perform extensive in-situ
measurements. Such processes include the formation of mesoscale eddies, fronts,
internal waves, the response of upper layer dynamics to rapid changes in the wind
field, or effects of changes in bottom topography, river discharges, or other boundary conditions that are not well known and difficult to predict with purely theoretical
approaches. Despite the coarse temporal sampling, repeated high-resolution current
measurements from space can be valuable for basic research and routine monitoring
in such regions.
R. Romeiser et al.
optimised ATI satellites for ocean applications could permit vector current measurements at an effective spatial resolution of 100 m and with improved spatial and
temporal sampling characteristics. The technology for such instruments is readily
available. Further development in this field must be driven by user demand and
should include dedicated validation campaigns. In the following we discuss promising applications. Some text and figures have been adapted from Romeiser and Runge
(2008).
5.4.1 Global Oceanography
Chapron et al. (2005) have demonstrated the generation of global surface current
maps at a spatial resolution on the order of 100 km from ENVISAT ASAR Wave
Mode data. Johannessen et al. (2008) have shown that ASAR Wide Swath data
can reveal large surface currents of the Agulhas Current that are not detected by
altimeters.
Both capabilities can be very useful for global circulation studies as well as for
studies on the dynamics of strong mesoscale current features in certain areas. The
potential spatial resolution improvement of the ATI technique by more than one
order of magnitude can be useful for studies on small-scale current features that have
a strong larger-scale effect on the upper-ocean circulation as well as on chemical and
biological processes.
For example, McGillicuddy et al. (2007) describe a stimulation of mid-ocean
plankton blooms by eddy/wind interactions. Some of the eddies of interest can be
seen in altimeter data, but an analysis of high-resolution current fields from singleantenna Doppler anomaly or ATI measurements, ideally in combination with water
colour and temperature data from other sensors, would be highly desirable for more
detailed investigations and improved model developments in this field.
5.4.2 Coastal Oceanography
The general circulation patterns in coastal seas are often well known and reproducible by numerical circulation models. Furthermore, many HF radars have been
installed within the last decade for a continuous monitoring of currents, waves,
and ship traffic in coastal regions (e.g. Gurgel and Schlick, 2007). However, quasigeostrophic dynamic processes on spatial scales of 1–10 km are still not entirely
understood, and they may be of interest for scientists and other users who are
unable to install coast-based remote sensing systems or to perform extensive in-situ
measurements. Such processes include the formation of mesoscale eddies, fronts,
internal waves, the response of upper layer dynamics to rapid changes in the wind
field, or effects of changes in bottom topography, river discharges, or other boundary conditions that are not well known and difficult to predict with purely theoretical
approaches. Despite the coarse temporal sampling, repeated high-resolution current
measurements from space can be valuable for basic research and routine monitoring
in such regions.