Springtime brings increased sunlight, bursts of nutrients, and changing water conditions to the Gulf of Alaska. The combination promotes massive blooms of phytoplankton—microscopic, plant-like organisms that turn sunlight into food and then become fodder for some of the richest fisheries on the planet.
The top image shows the southern Alaska coast and the Gulf of Alaska on May 2, 2014. It is a composite knitted together from several orbits of the Aqua satellite and its Moderate Resolution Imaging Spectroradiometer (MODIS). Two comma-shaped cloud formations (image center and far left) dominate the skies over the North Pacific Ocean. These clouds were likely moving around and ahead of a low-pressure system, showing some cyclonic circulation. Dark green traces of a phytoplankton bloom are just visible off of the Alaska coast at top center.
The second image shows a tighter MODIS view of the Gulf on May 9, 2014, when a substantial bloom of phytoplankton colored the waters south of Prince William Sound with green, chlorophyll-rich life. Closer to the coast, the water has a tan tint, a sign of sediment in the water—likely runoff from snowmelt-swollen rivers dumping their excess into the sea.