Salinity Processes in the Upper Ocean-Regional Study (SPURS)-2 is the second of NASA’s SPURS field campaigns. As part of a six-month Tropical Pacific Observing System (TPOS)-2020 pilot study in the eastern tropical Pacific, two Saildrone unmanned surface vehicles (USVs) were launched from Saildrone’s headquarters in Alameda, CA, and transited to the SPURS-2 field study region at 10°N, 125°W where they performed data calibration measurements with the NOAA ship Roger Revelle and Woods Hole Oceanographic Institution (WHOI) SPURS-2 buoy.
A primary objective of the mission was to evaluate Saildrone USV as a platform for observing tropical air-sea interaction and compare measurements with field-proven technology. The mission also demonstrated the ability of the saildrone to navigate challenging low-wind, strong-current conditions in the Intertropical Convergence Zone (ITCZ).
The global hydrological (water) cycle and how it could change in the future is one of the most important issues facing society (SPURS-2 Planning Group, 2015). Sea surface salinity (SSS) is a key indicator of water exchange between the atmosphere and the ocean. NASA’s Aquarius mission measured salinity with satellites, but in situ observations are necessary to better understand the processes modulating salinity and its role in the hydrological cycle.
A paper published in a special issue of Oceanography on SPURS-2 reports that the saildrone-ship-buoy comparisons “provide enhanced understanding of measurements by various platforms in a rapidly changing subsynoptic weather system” and indicates that the Saildrone USV could provide important contributions to the Global Ocean Observing System (GOOS).