Project Title:  Surface Water and Ocean Topography

PI Lead:  Oscar Schofield

Funding Agency: CIT – NASA Jet Propulsion Lab

Partners: Moss Landing Marine Labs

Period of Performance:4/22/2019 – 2/28/2020

Total Budget: $98,584

Project Summary:

Surface Water and Ocean Topography (SWOT) is a radar interferometry mission making SSH measurement over a swath 120 km wide. There is a nadir gap of 20 km where the error from interferometry is not meeting the science requirement, therefore, it is critical to constrain the sea surface height (SSH) measurement errors at 15-150 km wavelengths. Slocum gliders have been demonstrated to be a robust platform to maintain a sustained presence at sea. Gliders are autonomous underwater vehicles that collect vertical profiles of data by moving through the water column by changing their buoyancy.  When used in a station-keeping mode, the glider can stay within 0.5 km around the targeted location, which is smaller than the radius of the mooring watch circle that is on the order of the water depth in a region. Using the temperature and salinity data, the glider can reliably reproduce the upper ocean (0-300m) dynamic (steric) height signals obtained by moorings as demonstrated in the SWOT pilot effort conducted in 2017.

For the upcoming field season, we propose to improve our ability to calibrate/validate the future SWOT mission, by deploying a G2 Slocum glider in the energetic offshore waters along the California coast.  The goals will be to demonstrate the ability to help overcome the 20 km nadir gap of SWOT, and developing glider flight strategies for maintaining a tight watch circle in these currents that are more powerful then encountered in the 2017 effort.  The glider to be deployed will be outfitted with a propeller, providing extra maneuverability to address the strong currents.  The system will be outfitted with a lithium long duration battery pack, this will allow the system to conduct a several month mission.  During the deployment the glider piloting team will be experimenting with energy optimization to prolong mission lifetimes to ensure future deployments can be sustained for sufficient duration that the missions can be sustained throughout the burn in calibration/validation phase after the SWOT launch.