Click this image for an interactive introduction to the North Atlantic Bloom

Just as there are seasons on land, there is a seasonal cycle in the ocean, both physically and biologically. In the North Atlantic, this annual cycle produces phytoplankton blooms that feature the explosive growth of diatoms in concentrated areas. Observed each spring, the North Atlantc Bloom (NAB) is a phenomenon so large it can be observed from ocean-color sensing satellites in space.

The phytoplankton in this bloom play a significant ecological role as part of the carbon cycle, taking carbon dioxide from the atmosphere and starting the process of storing it in the ocean. In 2008, Dr. Mary Jane Perry and researchers from the University of Washington Applied Physics Laboratory, Woods Hole Oceanographic Institute, and Dalhousie University in Nova Scotia set out to better understand the mechanics and importance of this seasonal event.

For this project, traditional ship-based instruments were supplemented with new autonomous platforms, including Seagliders and Lagrangian Floats, and innovative sensors to detect chlorophyll fluorescence, optical backscattering, beam attenuation, oxygen and nitrogen (in addition to the standard temperature, conductivity, and pressure measurements). In all, over 60 data channels were sampled to give a time-space resolved picture of physical, biological, and chemical properties.

"What we're learning about eddies is that they're a critical part of life in the ocean. They shape ocean ecosystems in countless ways."-Mary Jane Perry

Traditionally thought to be triggered by a combination of increased sunlight and warming ocean waters, researchers from the NAB experiment recently co-authored a paper in Science offering up another cause. When the data from the NAB cruises was compared to 3-dimensional physical models, it was observed that blooms are initiated by eddies, even before this increased warming occurs. Eddies that form when colder northern water slips under lighter (and less dense) warm water from the south help the phytoplankton get to and remain at the surface of the ocean.