On our way

Crew and scientists are looking back at Honolulu as the R/V Melville is leaving port. We are headed toward the point (30°N, 167.45°W) where leg 1 stopped measuring about a week ago. There we will pick up work to finish section P2 across the Pacific all the way to San Diego, covering the eastern portion of the North Pacific basin (hence the E!).

Why are we doing this? What makes a group of 28 scientists plus crew spend several weeks out at sea, often under adverse conditions? In short: We would like to understand more about how the ocean works, what drives it, how it changes and what causes these changes.

Section P2 across the North Pacific at nominally 30°N is part of the U.S. CLIVAR and Carbon Repeat Hydrography Program that consists of several trans-ocean sections intended to be measured approximately every 10 years. The P2 section was last occupied in 2004 and prior to that in 1993/1994.

The CLIVAR (Climate Variability and Prediction) aspect of the program aims at understanding climate variability in the oceans. How much of the global warming is transferred to the deep ocean? Does this change circulation patterns of the oceans and are there potential consequences for the atmosphere, so-called feedbacks? The Carbon Program is concerned with how the increasing amount of CO₂ in the atmosphere – one of the most prominent CO₂ measuring stations is actually right in Hawaii near the top of Mauna Loa - affects the ocean and how much of it is transferred to and stored in the ocean. These are just a few of the key questions that oceanographers and atmospheric scientists would like to answer, and we will introduce more during the upcoming weeks.

To answer many of these questions, high-quality ocean data are needed. There are satellites that supply a large amount of data from the ocean surface, but they can not look into the ocean interior, i.e. below the surface. In recent years, autonomous instruments have been deployed all over the globe to measure the upper 2000 meter of the world's oceans. They do an excellent job at this, but most of them do not go to greater depths and they do not carry sensors for all of the ocean properties we are interested in. Thus, scientists (like us) still have to go out to sea to collect water sample data from a ship the good old way.

Here on the R/V Melville, several groups are measuring physical and biogeochemcial properties of the ocean such as salinity, temperature, velocity, oxygen, dissolved carbon, nutrients and many more. Hopefully, there will be a chance to meet all of the groups on this blog as our trip continues!

Looking back at Honolulu

by Gunnar Voet and Sabine Mecking