High-frequency radar observations of ocean surface currents
In: Carlson, C.A.; Giovannoni, S.J. (Ed.) (2013). Ann. Rev. Mar. Sci. 5. Annual Review of Marine Science, 5. Annual Reviews: Palo Alto. ISBN 978-0-8243-4505-1. 569 pp., more
In: Annual Review of Marine Science. Annual Reviews: Palo Alto, Calif. ISSN 1941-1405; e-ISSN 1941-0611, more
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| Keyword |
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| Author keywords |
HF radar, ocean remote sensing, search and rescue, sea echo |
| Abstract |
This article reviews the discovery, development, and use of high-frequency (HF) radio wave backscatter in oceanography. HF radars, as the instruments are commonly called, remotely measure ocean surface currents by exploiting a Bragg resonant backscatter phenomenon. Electromagnetic waves in the HF band (3–30 MHz) have wavelengths that are commensurate with wind-driven gravity waves on the ocean surface; the ocean waves whose wavelengths are exactly half as long as those of the broadcast radio waves are responsible for the resonant backscatter. Networks of HF radar systems are capable of mapping surface currents hourly out to ranges approaching 200 km with a horizontal resolution of a few kilometers. Such information has many uses, including search and rescue support and oil-spill mitigation in real time and larval population connectivity assessment when viewed over many years. Today, HF radar networks form the backbone of many ocean observing systems, and the data are assimilated into ocean circulation models. |
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