Salinity Processes in the Upper Ocean Regional Study (SPURS): Salinity Processes in the Upper-Ocean Regional Study: Part Two!August 10th, 2016 by Eric Lindstrom
By Eric Lindstrom
I am writing this while on a plane headed toward Honolulu to join the Research Vessel (R/V) Roger Revelle for six weeks at sea in the Pacific Ocean. It feels great to be heading to sea again. This NASA field campaign will last more than a year, with intense shipboard work near the beginning and end of the year. A web of sensors will be deployed to monitor one oceanic region over an entire year.
As Physical Oceanography Program Scientist at NASA Headquarters for nearly 20 years, my primary job is supporting our satellite missions related to measuring physical characteristics of the ocean (principally, temperature, salinity, sea level, and winds) and supporting the oceanographers that generate knowledge from such data. True understanding requires our fully appreciating the variations of the satellite data in the context of ocean physics. And that requires getting out there and getting wet from time to time!
R/V Revelle (home port: Scripps Institution of Oceanography, San Diego, California) leaves Honolulu on 13 August 2016 and returns to Honolulu on 23 September. The central location of the field work is about 8 days voyage southwest of Hawaii at 10N, 125W. Details of the expedition plans are available here. I hope to bring you a steady stream of expedition blog posts between now and the end of September 2016, including why NASA is focusing attention on this particular spot in the open ocean.
Since NASA’s launch in June 2011 of the Aquarius instrument to measure ocean surface salinity from space, the agency has embarked on field campaigns to understand surface salinity in great detail. This work has illuminated new ways of thinking about the ocean’s role in the global water cycle. Our field campaign, dubbed Salinity Processes in the Upper Ocean Regional Study-2 or SPURS-2, is the latest work to link the remote sensing of salinity with all the oceanic and atmospheric processes that control its variation.
The ocean is the primary source of moisture for the atmosphere. Evaporation of water from the sea surface leaves the ocean saltier (more saline). Precipitation over the ocean leaves the ocean fresher (less saline). The global pattern of average salinity at the sea surface approximately represents the balance of evaporation and precipitation at any locale (other factors such as river runoff, ice melt, and ocean motion and mixing complicate the picture). Many details of the interaction between ocean and atmosphere that lead to moisture transfer and signatures in ocean salinity are poorly understood. SPURS-2 is particularly focused on how, in one of the rainiest places on Earth, rainwater enters and impacts the ocean. Through this blog during the coming month, you will hear more about how and why oceanographers focus on such a problem.
The first SPURS campaign, which took place in the North Atlantic Ocean in 2012-2013, focused on the study of ocean processes where evaporation dominates the salinity of the surface ocean. I blogged during the September 2012 work from R/V Knorr. Among other things, we learned that surface salinity variations in that part of the world can be directly connected with precipitation patterns over the nearby continents. I’ll discuss that scientific finding and others in this blog over the coming month.
At the opposite extreme from SPURS-1, SPURS-2 focuses on an oceanic regime where precipitation dominates the salinity characteristics of the surface ocean. The two extremes call for significantly different approaches to measuring and studying the upper ocean. We will uses many of the same tools from SPURS-1 (instrumented moorings, profiling floats, surface drifters, and gliders) but deployed in new and novel ways.
The crew and scientific party on R/V Revelle will be more than 50 in all. As you read future blog entries you will get some sense of what its like for such a group to work closely together for six weeks in the confined space of an oceanographic research vessel. Seasickness? Food? Watches? Sleep? Drama? Boredom? Sea life? You’ll find out soon and get a sense of how some oceanographers go about their work, what technologies are involved, what is discovered, and how all this impacts lives, including yours, and what you might experience if you were aboard.