Research Expedition to Explore Ocean Salinity, Climate - Briefing Materials
NASA-funded researchers are making final preparations at the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Mass., for an ocean-going campaign designed to shed new light on the link between ocean salinity and shifts in global precipitation patterns.
The research voyage is part of a multi-year mission called the Salinity Processes in the Upper Ocean Regional Study (SPURS). The new data also will help calibrate the salinity measurements NASA's Aquarius instrument has been collecting from space. SPURS scientists aboard the research vessel Knorr leave Sept. 6 from Woods Hole. The researchers will spend about three weeks deploying instruments and taking measurements before sailing to the Azores to complete the voyage on Oct. 9. For more information on SPURS, contact Steve Cole at email@example.com
or Stephanie Murphy at firstname.lastname@example.org
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- Raymond Schmitt, senior scientist, Woods Hole Oceanographic Institution
- Dave Fratantoni, associate scientist, Woods Hole Oceanographic Institution
- Eric Lindstrom, physical oceanography program scientist, NASA Headquarters
The Salinity Processes in the Upper Ocean Regional Study (SPURS) research cruise will study a spot known as the Atlantic surface salinity maximum, located halfway between the Bahamas and the western coast of North Africa.
One of the most worrisome impacts of climate change is a possible acceleration of the global water cycle leading to more frequent droughts and floods.
The ocean retains a better record of changes in precipitation than the land, and translates these changes into variations in the salt concentration of its surface waters.
The salty areas of the ocean are getting saltier, while fresh areas are getting fresher. This indicates a strong intensification of the water cycle over the last decades.
The changes in global ocean salinity are larger than what climate models can explain. SPURS is designed to investigate this discrepancy and examine the oceanic processes influencing surface salinity.
The Research Vessel Knorr will serve as a platform for temperature, salinity, and meteorological measurements in addition to transporting a large fleet of robotic vehicles to the SPURS site in the tropical Atlantic.
Researchers will deploy an array of three oceanographic moorings at the SPURS site for a year: the WHOI surface flux mooring will measure meteorological parameters and fluxes between the ocean and atmosphere, while two NOAA profiling crawler (“prawler”) moorings will obtain meteorological observations and serial profiles along the mooring wire.
Satellite-tracked surface drifters will track water movement. SPURS will deploy profiling floats, modified from those used in the global Argo program to measure near-surface salinity, wind speed, and rain rate, and Lagrangian (free-floating) drifters equipped with multiple sensors to accurately track three-dimensional water movement.
SPURS will use several types of autonomous underwater vehicles. Two propeller-driven IVER2/Ecomapper vehicles will conduct short-term and small-scale surveys of salinity features. Two buoyancy-driven Slocum Gliders equipped with microstructure sensors will observe the intensity of ocean mixing. Three high-endurance, buoyancy-driven Seagliders will measure temperature, salinity, and microstructure in a 93-mi (150-km) box surrounding the SPURS moorings for a year.
Three sun-powered wave gliders equipped to measure temperature, salinity, and meteorological conditions will occupy a 62-mi (100-km) region near the SPURS moored array for a year.
SPURS will use a nested observational strategy: expendable devices and ships-of-opportunity will collect temperature and salinity measurements over a wide geographic area in the central tropical Atlantic. Moorings and small fleets of robotic vehicles will provide a sustained year-long presence in a smaller observational area. During research cruises, ship-deployed platforms will make high-resolution measurements of even smaller oceanographic features.
The Aquarius / SAC-D mission provides weekly and monthly global maps of ocean surface salinity. The satellite model depicted in this animation is an artist rendition and intentionally exaggerated so as to remain visible as it flies around the globe. (Credit: NASA's Goddard Space Flight Center)
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NASA's Aquarius instrument has been collecting ocean surface salinity measurements from space since August 2011 and using data from Argo, a global array of thousands of drifting profiling floats measuring the temperature and salinity of the upper layers of the ocean, for comparison and validation.
The data collected by the SPURS devices will be relayed via satellite to shore and integrated with numerical ocean models and satellite observations.
Two years of simulated surface salinity from the HYCOM eddy-resolving numerical ocean model. The three panels show the evolution of surface salinity in successively smaller regions centered on the SPURS operational area. Yellow dots represent the position of SPURS moorings and an schematic of planned wave glider trajectories is shown as light white lines. (Credit:Dave Fratantoni, Woods Hole Oceanographic Institution)
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