Spring Has Sprung in the Northwest Atlantic

Meteorological spring has arrived in the Northern Hemisphere. It also appears to have arrived off the northeastern coast of the United States.

In the early afternoon on March 29, 2026, the Ocean Color Instrument (OCI) on NASA’s Plankton, Aerosol, Cloud, Ocean Ecosystem (PACE) satellite captured a natural-color view of the Atlantic Ocean splashed with shades of green and milky blue from Norfolk to Cape Cod. While some of the color could be due to outflows from coastal rivers and sediment churned up by spring storms, at least some of the greens and light blues offshore are phytoplankton blooms. PACE observes ocean color in more than 100 wavelengths precisely so that it can detect such blooms and discern what species are in them. 

The map below affirms the presence of phytoplankton. Using the lens of near-real time (NRT) chlorophyll-a data from OCI, we can see rough estimates of the amount of sunlight-capturing pigment in the water – a proxy for detecting phytoplankton. Reds, oranges, and yellows delineate areas with higher levels of chlorophyll.

Phytoplankton are to the ocean what grasses and ground cover are to land: primary producers, a basic food source for other life, and the main carbon recycler for the marine environment. Diatoms, coccolithophores, algae, and other forms of phytoplankton are floating, plant-like organisms that soak up sunshine, sponge up nutrients, and create their own food (energy).

As springtime brings increasing hours of sunlight to the North Atlantic, phytoplankton populations surge back from winter lows. Like terrestrial plants, phytoplankton need sunlight and nutrients to thrive. Springtime brings both. The Gulf Stream, which makes many of the rings and swirls in the chlorophyll image, also helps churn the sea and capture cold water masses that usually carry nutrients.

The image pair below shows the significant increase in chlorophyll levels in the region from the end of February 2026 to the end of March.