What Is Deep Argo?

The scientific community agrees that a systematic sampling of the full ocean depth is needed to close the planetary budgets of heat and freshwater, and the global sea level budget. The strength and variability of the large-scale ocean circulations that extend from the sea surface to the ocean bottom play significant roles in the uptakes and transports of heat and freshwater, and melting of sea ice. Since the implementation of the Argo program, profiling floats were limited to the top half of the sea (0-2000 m) and the accuracy of sensors was similarly limited to upper ocean levels of temperature and salinity variability. A new generation of autonomous floats called Deep Argo will sample the full ocean volume. Deep Argo float models include the Deep SOLO and Deep APEX capable of reaching 6000 m, and the Deep ARVOR and Deep NINJA designed to sample to 4000 m. Regional Deep Argo arrays in the Southwest Pacific Basin, South Australian Basin, Australian Antarctic Basin, and North Atlantic Ocean are leading the way forward to implement a standing Deep Argo array of 1228 floats. An exciting transition to systematic full-depth global ocean observations is happening.

Technology challenges

One of the challenges facing Deep Argo is that the CTD sensor used on standard Argo floats was not designed to go below 2000 m depth. Therefore, SeaBird has been working to develop a new CTD sensor that will be accurate down to 6000 m. This new CTD, named the SBE-61, has not yet achieved its aspirational goals of (± .001C, ±.002 psu, and ± 3 dbar) but is progressing relative to those goals.  To see the Deep Argo float models, click here.

Pilot arrays

Deep Argo Task Team

Links to related papers

Gasparin, F., M. Hamon, E. Rémy, and P.-Y. L. Traon, 2020: How Deep Argo Will Improve the Deep Ocean in an Ocean Reanalysis. Journal of Climate, 33, 77-94, https://doi.org/10.1175/JCLI-D-19-0208.1

Johnson, G. C., S. G. Purkey, N. V. Zilberman, and D. Roemmich, 2019: Deep Argo Quantifies Bottom Water Warming Rates in the Southwest Pacific Basin. Geophysical Research Letters, 46, 2662-2669, https://doi.org/10.1029/2018GL081685

Roemmich, D., J. T. Sherman, R. E. Davis, K. Grindley, M. McClune, C. J. Parker, D. N. Black, N. Zilberman, S. G. Purkey, P. J. H. Sutton, and J. Gilson, 2019: Deep SOLO: A Full-Depth Profiling Float for the Argo Program. Journal of Atmospheric and Oceanic Technology, 36, 1967-1981, https://doi.org/10.1175/JTECH-D-19-0066.1

Zilberman, N, Roemmich D., 2017. The Argo Program samples the deep ocean. US CLIVAR Variations, 2(15):29-33

Jayne, S. R., D. Roemmich, N. V. Zilberman, S. C. Riser, K. S. Johnson, G. C. Johnson, and S. R. Piotrowicz, 2017: The Argo Program: Present and Future. Oceanography, 30, 18-28, http://dx.doi.org/10.5670/oceanog.2017.213

Zilberman, N. V., 2017: Deep Argo: Sampling the Total Ocean Volume in State of the Climate in 2016. Bull. Am. Meteorol. Soc., 98, S73-S74, https://doi.org/10.1175/2017BAMSStateoftheClimate.1

Le Reste, S., V. Dutreuil, X. André, V. Thierry, C. Renaut, P.-Y. L. Traon, and G. Maze, 2016: “Deep-Arvor”: A New Profiling Float to Extend the Argo Observations Down to 4000-m Depth. Journal of Atmospheric and Oceanic Technology, 33, 1039-1055, http://dx.doi.org/10.1175/JTECH-D-15-0214.1

Johnson, G. C., J. M. Lyman, and S. G. Purkey, 2015: Informing Deep Argo Array Design Using Argo and Full-Depth Hydrographic Section Data. Journal of Atmospheric and Oceanic Technology, 32, 2187-2198, http://dx.doi.org/10.1175/JTECH-D-15-0139.1

Kobayashi, T., 2013: Deep NINJA collects profiles down to 4,000 meters. Sea Technology, 54, 41-44, https://www.sea-technology.com/features/2013/0213/deep_ninja.php

Kobayashi, T., 2013: A realization of a profiling float for deep ocean observation. Engineering Materials, 61, 67-70,

Kobayashi, T. and M. Tachikawa, 2013: An introduction of a domestic deep float, DEEP NINJA, and its deep/bottom layer observations in the Southern Ocean. JOS News Letter, 3,