Science: SPURS

Since August 2011, NASA’s satellite instruments have revealed how sea surface salinity changes over time with unprecedented detail. This new perspective of our ocean provided the scientific motivation for the Salinity Processes in the upper-Ocean Regional Study (SPURS), a coordinated field campaign to understand causes behind the patterns and variations of salinity at the ocean’s surface.

Salty areas are getting saltier, fresh areas are getting fresher, indicating a strong intensification of the water cycle.
Durack and Wijffels (2010), Journal of Climate; Durack, Wijffels and Mercer (2012), Science

Studies indicate that, over the past 50 years, high-salinity regions (subtropics) have been getting saltier and the low-salinity regions (tropical rain belts) have been getting fresher. This is consistent with a warmer world where the atmosphere holds more water vapor. To learn more about the processes behind such salinity trends, SPURS-1 and -2 activities have been conducted in representative “salty” and “fresh” areas of our ocean, respectively (see table below).

SPURS has been designed to examine the salinity balance in the upper ocean through observation of salinity and ocean circulation at various time scales (annual, daily, minutes) and spatial scales (ocean basin, mesoscale, microstructure). The combined analysis of satellite and SPURS in situ data is intended to improve salinity-related computer models. Such information is critical in modeling the dynamics of many ocean phenomena. It also sheds light on the future of our water cycle, one of the most critical issues of climate change facing society.

Focus High evaporation Heavy rain
Region Subtropical N. Atlantic E. Tropical Pacific
Mooring location 25°N / 38°W 10°N / 125°W
Cruise dates Sep-Oct 2012
Mar-Apr 2013
Sep-Oct 2013
Aug-Sep 2016
Oct-Nov 2017
Research vessels Endeavor-1 and -2
Sarmiento de Gamboa
Lady Amber

Additional Resources


Zippel, S., Farrar, J.T., Zappa, C., Miller, U., St. Laurent, L., Ijichi, T., Weller, R., McRaven, L., Nylund, S., and Le Bel, D. (2021).
Moored Turbulence Measurements using Pulse-Coherent Doppler Sonar
, J. Atmos. Ocean. Technol., doi: 10.1175/JTECH-D-21-0005.1.
Wills, S.M., Cronin, M.F., and Zhang, D. (2021).
Cold Pools Observed By Uncrewed Surface Vehicles in the Central and Eastern Tropical Pacific
, Geophys. Res. Lett., 48 (10), e2021GL093373, doi: 10.1029/2021GL093373.
SPURS study areas
SPURS-2 data tool
The SPURS-2 Data Tool (shown above) allows you to browse datasets collected during the SPURS-2 Field Campaign.

In Situ Instruments

[Click on the main image to learn more]

  • Underway CTD
  • Microstructure profiler
  • Conductivity, temperature, and depth (CTD) rosette
  • Acoustic doppler current profiler
  • Surface flux mooring
  • Prawler mooring
  • Lagrangian drifter
  • Surface drifter
  • Profiling float
  • IVER 2/Eco-Mapper
  • Slocum glider
  • Seaglider
  • Wave glider