The Scripps Institution of Oceanography research vessel Melville returned to San Diego after a two-and-one-half year expedition. Nearly 50 research projects in the western Pacific Ocean were completed in that time. KPBS Reporter Ed Joyce was onboard the vessel as it docked in Point Loma.
The UC San Diego research vessel Melville travelled more than 100,000 nautical miles on the trip. The vessel was used in 47 research missions - including one to understand how Earth's geomagnetic field works. Scripps geophysicist Jeff Gee launched and recovered unmanned aerial vehicles at sea. The vehicles provided data that allowed Gee to map fluctuations in the Earth's magnetic field.
Gee: Well this is how we tell the age of the seafloor and that in turn tells us how plates have moved around. So we can reconstruct how plates have moved around by looking at these magnetic, what are called magnetic anomalies.
He says the most recent observations show a lessening of the magnetic field's intensity.
The Earth's magnetic field has been weakening since 1845 when scientists first started tracking it. Research shows a weak field would leave Earth vulnerable to geomagnetic storms that could disrupt electrical grids and widen the ozone holes in the atmosphere.
Gee says it's important to study the ocean floor because it helps us understand more about our planet.
Gee: We were in a part of the Pacific that has been, there there was virtually no data there before. So we discovered some trends in sort of the fabric of the seafloor that were a bit different than we thought would be there.
Some of the other projects included observing a deep-sea volcanic eruption and measuring the physical properties of sound traveling through the ocean.
The Melville is the oldest active ship in the U.S. academic research fleet. It heads out again next Tuesday for a cruise off the California coast to document the ecosystem of the California ocean current system.
Ed Joyce, KPBS News.
