GP15 by the numbers

plastic prison
Inside the main lab’s bubble, some of GP15’s scientists found it necessary to create reminders that time was indeed passing. Image: Alex Fox

Days at sea: 67

People on board: 59 (37 science party; 22 crew)

Stops between Seattle, WA (departed 9/18/18) and Papeete, Tahiti (arrived 11/25/18):

1 (Hilo, Hawaii 10/21/18-10/25/18)

gp15 track edit

Stations sampled: 36

Winds gusting up to 40 knots peeled spray off the tops of the waves near Alaska. Image: Alex Fox

Largest waves: ~15-foot swell near Alaska

Chief Scientist Greg Cutter of Old Dominion University prepares to release a confused seabird. Image: Alex Fox
Birds rescued: 4

Flying fish landed on deck: Countless

oceanic whitetip winner
The crystal clear waters of the South Pacific offer a virtually unobstructed view of this oceanic white-tip shark. Image: Alex Fox

Sharks sightings: ~6

4 dolphins portside kc cropped
Pacific white-sided dolphins off the coast of British Columbia, Canada. Image: Kevin Cahill

Dolphin sightings: 1

Whale sightings: 0 (unless nobody told me)

Leave it to the Co-chief Scientists to create a GEOTRACES GP15 themed jack-o-lantern. Image: Alex Fox

Holidays at sea: 2

Midterm elections at sea: 1

Toaster repairs: 3

Internet data usage: 450 gigabytes

pumps ahoy
One of the pumps comes back on board the R/V Roger Revelle at sunset. Image: Alex Fox

Liters of seawater filtered by the pumps sampling system: 491,819

glassy ctd1
Calm waters offer a unique view of the non-trace metal CTD rosette entering the Pacific. Image: Alex Fox

Seawater collected by the non-trace metal CTD rosette: 34,200 liters

gtc drip
The trace metal CTD rosette gets hauled back on board. Image: Alex Fox

Seawater collected by the trace metal CTD rosette: 20,736 liters


dr buck
Clifton Buck of the Skidway Institute of Oceanography with his equipment for sampling air and rainwater on GP15. Image: Alex Fox

Volume of air sampled for aerosol trace elements: 315,882 cubic meters

fuzzy erin
Tubes awaiting samples in the hydro-lab of the Roger Revelle. Scripps ODF Chemistry Technician Erin hunt monitors her samples in the background. Image: Alex Fox

Nutrient measurements performed on board: 21,712

B L Van
Trace metal CTD rosette Super Technicians Laramie Jensen of Texas A&M University and Brent Summers of the University of South Florida. Image: Alex Fox

From trace metal CTD rosette Super Techs Laramie Jensen and Brent Summers:

  • Sample bottles filled: 15,758
  • GoFlo bottles racked inside lab van: 1,700
  • Bottle rinses: 47,274
  • Longest work day: 39 hours
  • GoFlo bottles lost to sea: 1  (RIP #45);
  • Pallets filled with seawater samples: 12.5

A selection of mechanical issues encountered at sea:

Slip ring repair
Left to right: CTD technician Kyle McQuiggan, Research Technician Keith Shadle and multi-talented Data Analyst Joseph Gum work together to repair the trace metal CTD rosette’s connection to the ship. Image: Alex Fox
  • The trace metal CTD rosette’s electrical connection to the ship via its cable failed. Learn more.
  • During the rough weather encountered in the northern portion of the expedition, the surface sampling system, called the fish, had considerable problems.
    • The fish’s torpedo is designed to keep it submerged and away from the ship, but in big swell it began breaching. This required numerous adjustments of its fin angles and countless hours of nervous observation.
  • During station 11, the motor on the A-frame, used to angle the trace metal CTD rosette into the sea, seized up.
    • The ship’s electrician Harry Smith rebuilt the motor, which worked well for the rest of the expedition.
Co-chief Scientist Phoebe Lam of the University of California, Santa Cruz and others removed the pump’s damaged section of cable from the winch.  Image: Alex Fox
  • At Station 16, a winch operator error damaged the cable used to lower the pump sampling system. The cable was so damaged it wasn’t clear it could hold the pumps without breaking.
    • After many hours applying temporary repairs (Scotch coat and electrical tape), pump operations resumed for the next 2 stations.
    • During GP15’s port stop in Hilo, Hawaii, the team cut off the thousands of feet of damaged cable.
    • Co-chief Scientist Phoebe Lam arranged for a replacement cable to be flown in from UC Santa Cruz.
    • A technician from Cortland Cable, the manufacturer, flew in to splice on a ~12,000-foot section of new cable to the remaining ~10,000 feet of undamaged cable.

You can find an archive of blog posts created during this expedition here.

Blog posts created or edited by Alex Fox.

Follow GEOTRACES GP15 on

Funding for this research is provided by NSF Chemical Oceanography.



GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.

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