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antennae arrays of up to 300 m along the coastline posing aesthetic and regulatory
obstacles. These remote ocean sensing systems operate at lower power, typically
below 30 W per antenna, and can consist of arrays of up to 12 individual antennae.
In addition to ocean surface current mapping, HF radar can be used to locate and
track vessels at sea, to make wind and wave measurements, and, under the proper
conditions, to detect oncoming tsunami waves (Paduan and Washburn 2013).
Lagrangian Current Observation Lagrangian observations are of moderate use
for coastal applications since the spatial scope of water bodies within convoluted
coastlines restricts effective coverage to short distances, tens or hundreds of meters
in the very nearshore to mid-distances measured in tens of kilometers. Drift of a
Lagrangian buoy outside of such a radius of interest can occur within hours to weeks
making further data of decreasing usefulness to the question at hand and requiring
buoy retrieval and redeployment unless the buoy is purposely expendable. Nevertheless, Lagrangian drifter measurements, coupled to Eulerian measurements and
tidal predictions, find useful application for validation of high frequency radar
coastal surface current mapping (e.g., Corredor et al. 2011). Dedicated surf zone
Fig. 2.6 Radial vector returns from a single antennae emplacement
2.2 Electronic Sensors and Instruments for Ocean Observing