Ocean color

The subtle shifts in the sea’s color seen from space, from deep blue to green. Those tints reveal what’s in the water — mostly microscopic plant life, sediment, and dissolved material.

Why it matters

Ocean color tracks phytoplankton, the base of the marine food web that also draws down carbon dioxide, so it underpins studies of fisheries, harmful algal blooms, and the ocean’s role in climate.

Where you’ll meet it

• PACE is NASA’s newest ocean-color mission, with its OCI sensor measuring many wavelengths to identify plankton types.
• MODIS and VIIRS provide the long-running global ocean-color record.
• SeaWiFS, an earlier mission, pioneered routine ocean-color monitoring from space.

In plain terms

It’s like reading the sea’s mood by its color — clear blue water is nearly empty of life, while a greener tint means it’s teeming with tiny floating plants.