Page 23: of Marine Technology Magazine (September 2023)

phy relative to direct ocean measurements. In the open ocean, sea surface height (SSH) is connected to the distribution of temperature, salinity, and density, as well as ocean currents.

These properties must be measured with high vertical and temporal resolution to provide a ground truth for the satel- lite. The four Wirewalker moorings are part of an overall 11 mooring array, situated directly under the satellite ? ight path to gather snapshots of steric height for comparison with the measurements gathered from space. The Cal/Val moor- ings are designed to withstand all weather and provide high

Del Mar Oceanographic data density in the upper part of the ocean, where the den- www.delmarocean.com sity ? eld changes rapidly. Per experiment requirements, the

Del Mar Oceanographic (DMO) was established in 2015, Wirewalkers will pro? le the upper 500 m of each mooring, but its roots are deeper with the initial development of the using single CTDs to provide the data that would otherwise

Wirewalker, a wave-powered vertical pro? ling system de- be required from numerous instruments closely spaced in veloped by the Ocean Physics Group at Scripps Institution depth. A key innovation for Ca/Val is the development of a of Oceanography. Today Wirewalker is now produced com- robust mooring that enables real time communications from mercially by DMO under exclusive license from the Uni- both the Wirewalker and from numerous ? xed sensors. The versity of California. Systems are in the ? eld globally, sup- design combines a conventional taut mooring from the sea porting coastal pollution monitoring, aquaculture, coastal ? oor to a subsurface ? oat at 600 m depth. The Wirewalker ecology, basic science and climate research. is operational in the top 500m, producing vertical pro? les

In 2022, DMO secured funding from NASA’s Jet Propul- of density roughly every hour. Using inductive technology, sion Laboratory (JPL) to provide Wirewalker pro? lers to sensor data from throughout the entire water column are ground truth a new Surface Water and Ocean Topography transmitted in real-time. For Ca/Val, the Wirewalkers will (SWOT) satellite. Wirewalkers were installed on four deep- be equipped with CTDs. An initial test of the Cal/Val moor- ocean moorings off the coast of California for the calibra- ing concept was conducted during winter 2019-2020. This tion and validation (Cal/Val) of the new satellite. Onboard site was 300 km west of Monterey, California, in the heart the satellite, a next-generation altimeter using a wide-swath of the North Paci? c storm track, and at a water depth of ap-

Ka-band interferometer (KaRIn) will collect detailed glob- proximately 5 km. During this pre-launch ? eld campaign al measurements of Earth’s surface water and sea surface phase, the Wirewalker yielded about 3500 roundtrip pro? les height. The satellite launch was planned for November 2022 to 500m (~3500 km traveled), during its 86 days of deploy- and moorings have been in the water since March 2023. Cal- ment. The mooring allowed a full-ocean depth estimate of ibration and validation are critical to any satellite mission. SSH with an uncertainty of less than 1 cm, according to re-

For the SWOT, a portion of the Cal/Val activities include the sults published this year in the Journal of Atmospheric and assessment of the satellite estimates of sea surface topogra-

Oceanic Research by a team of institutions led by JPL.

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