Ocean surface features and currents measured with synthetic aperture radar interferometry and HF radar

Hans C Graber, Donald R. Thompson, Richard E. Carande

Research output: Contribution to journalArticle

80 Citations (Scopus)

Abstract

This paper describes the results of the first quantitative comparison between high-resolution ocean surface current fields extracted from interferometric synthetic aperture radar (INSAR) measurements and those from an high-frequency (HF) ocean surface current radar (OSCR) system. Data from each of these radar systems along with supporting measurements from shipboard and buoy-mounted sensors were collected during the High-Resolution Remote Sensing Experiment (High-Res) on June 20, 1993, on the continental shelf off the coast of Cape Hatteras, North Carolina. Both components of the surface current were obtained from the INSAR system at roughly 10-m resolution from two orthogonal flight legs over the region separated in time by about 30 min. The OSCR system measured two-dimensional surface current vectors at about 1-km resolution over this same region, while the USNS Bartlett was collecting hydrographic samples and near-surface current measurements. Two-dimensional wave spectra as well as meteorological and additional current measurements were collected at two buoys within the experimental area. We discuss in the paper two techniques for eliminating the effect of surface wave motion on the INSAR current estimates. One method relies on some knowledge of the local wind and wave field and the use of a microwave scattering model. The other method makes use of a few in situ current measurements spaced at different range locations across the INSAR image. Using either of these techniques, we find that the agreement between the INSAR and OSCR current estimates is generally very good. Furthermore, the INSAR current and magnitude imagery show the presence of undulating, surface features where abrupt changes in the current speed and direction occurred. The ship surveys indicate that these features were caused by the collision of water masses of different density. We show for the first time in this paper a high-resolution, area-extensive vector surface current map derived from the INSAR of the two-dimensional flow in the vicinity of these features. Our results demonstrate convincingly that high-resolution oceanic surface current vectors can be derived from INSAR current measurements and that these measurements may be very beneficial for detailed studies of the dynamics of small-scale surface features in regions of strong current divergences or shears.

Original languageEnglish (US)
Pages (from-to)25813-25832
Number of pages20
JournalJournal of Geophysical Research C: Oceans
Volume101
Issue numberC11
StatePublished - 1996

Fingerprint

radar interferometry
ocean surface
synthetic aperture radar
Synthetic aperture radar
Interferometry
radar
sea surface
interferometry
Radar
Electric current measurement
Radar systems
Radar measurement
vector currents
high resolution
two-dimensional flow
wave spectrum
wave field
Buoys
wind field
surface wave

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Earth and Planetary Sciences (miscellaneous)
  • Atmospheric Science
  • Geochemistry and Petrology
  • Geophysics
  • Oceanography
  • Space and Planetary Science
  • Environmental Science(all)
  • Astronomy and Astrophysics

Cite this

Ocean surface features and currents measured with synthetic aperture radar interferometry and HF radar. / Graber, Hans C; Thompson, Donald R.; Carande, Richard E.

In: Journal of Geophysical Research C: Oceans, Vol. 101, No. C11, 1996, p. 25813-25832.

Research output: Contribution to journalArticle

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AB - This paper describes the results of the first quantitative comparison between high-resolution ocean surface current fields extracted from interferometric synthetic aperture radar (INSAR) measurements and those from an high-frequency (HF) ocean surface current radar (OSCR) system. Data from each of these radar systems along with supporting measurements from shipboard and buoy-mounted sensors were collected during the High-Resolution Remote Sensing Experiment (High-Res) on June 20, 1993, on the continental shelf off the coast of Cape Hatteras, North Carolina. Both components of the surface current were obtained from the INSAR system at roughly 10-m resolution from two orthogonal flight legs over the region separated in time by about 30 min. The OSCR system measured two-dimensional surface current vectors at about 1-km resolution over this same region, while the USNS Bartlett was collecting hydrographic samples and near-surface current measurements. Two-dimensional wave spectra as well as meteorological and additional current measurements were collected at two buoys within the experimental area. We discuss in the paper two techniques for eliminating the effect of surface wave motion on the INSAR current estimates. One method relies on some knowledge of the local wind and wave field and the use of a microwave scattering model. The other method makes use of a few in situ current measurements spaced at different range locations across the INSAR image. Using either of these techniques, we find that the agreement between the INSAR and OSCR current estimates is generally very good. Furthermore, the INSAR current and magnitude imagery show the presence of undulating, surface features where abrupt changes in the current speed and direction occurred. The ship surveys indicate that these features were caused by the collision of water masses of different density. We show for the first time in this paper a high-resolution, area-extensive vector surface current map derived from the INSAR of the two-dimensional flow in the vicinity of these features. Our results demonstrate convincingly that high-resolution oceanic surface current vectors can be derived from INSAR current measurements and that these measurements may be very beneficial for detailed studies of the dynamics of small-scale surface features in regions of strong current divergences or shears.

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