@sciam declining phytoplankton in ocean

sciam

Plant Strife: Satellite measurements show declining phytoplankton in ocean currents http://bit.ly/dLwNAD

http://www.scientificamerican.com/

How green is Earth? That's a question that NASA's Sea-viewing Wide Field-of-view-Sensor Project, known as SeaWiFS, has been asking for the past 13 years. This image shows SeaWiFS' average measurements from 1998 to 2010.

SeaWiFS, on board the OrbView 2 (aka SeaStar) satellite measures the wavelengths of light reflected by phytoplankton (microscopic marine plants) and algae that use chlorophyll for photosynthesis. Over the oceans, SeaWiFS data indicate the concentration of phytoplankton floating on the surface. Scanning land, the sensor calculates the density of vegetation as a normalized difference vegetation index (NDVI). An NDVI of 0 means no green leaves, whereas an NDVI near 1.0 indicates a thick forest.