Physical oceanographers will sometimes point out that the ocean has weather and seasons, much like the atmosphere. Masses of water with different temperatures, salinities, and nutrient levels clash and mix like warm and cold fronts in the air. Different plant-like species—phytoplankton—bloom, spread, and die back with the different conditions. Ocean currents swirl in turbulent fronts and eddies—much like tornadoes and hurricanes, though far more productive than destructive.

Springtime in the North Atlantic Ocean is a time of great change, turbulence, and productivity. Increasing sunlight, nutrient runoff from land and upwelling from the deep, and changeable atmospheric weather all conspire to color the ocean surface with interesting patterns. The composite image above shows the northwest Atlantic Ocean on May 14, 2015, with the New England and Canadian Maritimes in the background. The image was constructed from data acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Suomi NPP satellite. Colors were enhanced to make the blooms more visible.

On the left side of the image, several circular patterns are traced out by the light green phytoplankton near the surface. These rings are likely eddies that have spun off of the Gulf Stream, which turns east toward Europe in this region. The underwater plateau known as Georges Bank is also made visible (indirectly) by the plankton. The Labrador Current and the Gulf Stream meet in this area, and the relatively shallow water promotes an abundant crop of phytoplankton, marine plants, shellfish, finfish, and marine mammals, all the way up the food chain. The bank is marked by bright swirls of color in the image.

Patches and swirls of phytoplankton continue to the north and east from the bank, indicating regions where there are significant nutrients near the surface and other water conditions that promote blooms. Though it is very difficult to identify the genus and species of phytoplankton from a satellite, researchers working from ships in the North Atlantic confirmed that at least some of the phytoplankton blooming in May were diatoms, including Guinardia delicatula.

The Gulf of Maine and Georges Bank have historically been some of the most productive fishing grounds on the planet. Overfishing and pollution brought significant declines in the late 20th century, though regulation and changes in fishing practices may now restore some of the abundance in the local waters. Researchers from the Woods Hole Oceanographic Institution, North Carolina State University, and NOAA have been regularly monitoring the region with ship-based studies, ocean models, and automated, moored instruments in order to keep track of phytoplankton and algae species, particularly those that lead to toxic algae blooms.

NASA image by Norman Kuring, NASA Ocean Color group. Caption by Mike Carlowicz, with image interpretation from Norman Kuring (NASA) and Dennis McGillicuddy, Don Anderson, and Heidi Sosik (Woods Hole Oceanographic Institution).