Strong currents off the coast of California are pulling cold, deep currents up from the sea floor to the surface. Called upwelling, these nutrient-rich waters are a boon to sea life, such that they support thriving populations of microscopic marine plant life. On March 16, 2004, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) captured these images of phytoplankton blooming in an upwelling area in the Pacific Ocean off the California coast.
Phytoplankton can be seen from space when they grow in large colonies. Chlorophyll in the plants tints the water green in true-color satellite imagery, such as the top image. Here, natural variations in the water color are caused either by different phytoplankton communities or the same communities growing at different depths in the ocean. The lower image shows chlorophyll concentrations in bright colors. The highest concentrations, shown in red and black, are near the coast.