On June 9, 2019, four Saildrone Explorer uncrewed surface vehicles (USVs) were deployed from Honolulu, HI, for a mission in the Central Equatorial Pacific. The 2019 TPOS Mission was the third of three missions funded by the NOAA Office of Oceanic and Atmospheric Research (OAR)/CPO/GOMO and NOAA/OMAO as a pilot study for the Tropical Pacific Observing System (TPOS)-2020 project.

Each vehicle carried an Acoustic Doppler Current Profiler (ADCP) in addition to the Saildrone metocean sensor package. The core CTDs were RBR instruments mounted in the flowthrough tunnel in the keel and a pumped SBE37 at the outflow of the flowthrough tunnel. SD-1066 and SD-1067 also carried an ASVCO2 carbon flux and pH system, a SPN1 shielded shortwave radiometer, and an Eppley longwave radiometer. Carbon system data, including its Prawler conductivity, temperature, depth (CTD) data, are served through a separate repository.

After performing ADCP bottom track testing on Penguin Bank, the vehicles proceeded to the WHOTS mooring for an intercomparison study. On June 17, 2019, SD-1067 returned to shore for servicing. After SD-1067’s ADCP bottom tracking was performed again, all four vehicles began their transit to the Tropical Atmosphere/Ocean (TAO) mooring at 9°N, 140°W, on June 20, 2019, and then sailed south towards the equator.

In addition to intercomparisons against the 0°N, 140°W TAO buoy, several experiments were performed to survey scales of variability in the equatorial region and the structure of the cold tongue front. An experiment in the InterTropical Convergence Zone (ITCZ) was performed before returning to Hawaii for a final intercomparison against the WHOTS mooring. The mission concluded on December 20, 2019. All four saildrones were recovered in Honolulu in early January 2020.

The principal investigators were Meghan Cronin (NOAA PMEL), Dongxiao Zhang (UW Joint Institue for the Study of Atmosphere and Ocean [JISAO]), Adrienne Sutton (NOAA PMEL), and Christian Meinig (NOAA PMEL). Samantha Wills (UW JISAO) was a postdoctoral fellow with the project, acting as a PI and mission manager during this mission.

This data set is hosted by NOAA PMEL and contains the delay-mode data from the Saildrone core. These data have not been quality controlled. ADCP and carbon data is not included. This data set is one year of a multi-year mission 2017–ongoing. Additional data sets can be downloaded directly from NOAA PMEL.