National Oceanic and Atmospheric Administration

Atlantic Oceanographic and Meteorological Laboratory

Physical Oceanography Division

RAPID-MOCHA-WBTS array suggests that the Atlantic circulation has changed

AOML oceanographers Christopher Meinen and Molly Baringer participated in the development of a new thirteen-year-long record of the daily Atlantic ocean overturning that has recently been released. This project is a collaboration between a large team of researchers at NOAA, at the University of Miami ,and at the National Oceanography Centre in Southampton, United Kingdom. This time series, which is widely considered to be one of the "Gold Standard" observing systems for the meridional overturning circulation (MOC), has led to numerous publications since the trans-basin measurement array (picture below) was first deployed in 2004. These important data are made available freely on the web, and a publication based on the latest update of the record was recently published.

The manuscript "The North Atlantic Ocean Is in a State of Reduced Overturning", led by Dr. David Smeed in Southampton and involving the contributions of many members of the international team including Drs. Meinen and Baringer, was recently published in the journal Geophysical Research Letters. The study documents how the transport associated with the Atlantic MOC appears to have decreased in 2009, and it appears that the transport has remained roughly stable at this reduced level in the years since 2009. Variations in the MOC are known to be associated with variations in sea level, precipitation patterns, and extreme weather including heat waves and hurricane intensification, so the observed change in the MOC may have significant implications for the broader climate system and human society.

Diagram illustrating the RAPID-MOCHA-WBTS array at 26.5°N in the North Atlantic (Courtesy D. Rayner).

Smeed, D.A., Josey, S.A., Beaulieu, C., Johns, W.E., Moat, B.I., Frajka‚ÄźWilliams, E., Rayner, D., Meinen, C.S., Baringer, M.O., Bryden, H.L. and McCarthy, G.D., 2018. The North Atlantic Ocean is in a state of reduced overturning. Geophysical Research Letters. [Link to Manuscript]