Elevated Chlorophyll in Micronesia

Something unusual was happening in the ocean around Micronesia during October, 2013. Ribbons of higher chlorophyll water extended roughly 500 kilometers east of Chuuk Lagoon and of the Senyavin Islands by mid month (see the image at right and the two images below). Earlier data from the same Aqua-MODIS instrument indicate that the visibly increased phytoplankton biomass began near Chuuk Lagoon in late September and to the east of Pohnpei about the beginning of October. Comparison of the positions of a distictive feature near the easternmost end of the Senyavin plume in the two images below yields a rough current estimate of about a half a meter per second toward the east, which is consistent with how far the eastern end of the plumes have extended from their respective island groups over the course of half a month.

The reason for calling this event unusual is that no similar event appears in any of the previously collected Aqua-MODIS data. Below the chlorophyll color scale you will find an animation showing chlorophyll concentrations around this part of Micronesia for each of the 136 months that Aqua-MODIS has been in operation so far. The long plumes only appear in October of 2013.

Further investigation would be needed to discover possible causes of this event.

chlorophyll concentrations around the Senyavin Islands on 11 October 2013

11 October 2013

chlorophyll concentrations in Micronesia on 12 October 2013

12 October 2013

chlorophyll concentrations in Micronesia on 13 October 2013

13 October 2013

Note that heavy sun glint contamination over the western portion of the above image reduces the accuracy of the chlorophyll estimates. Differences in background chlorophyll concentrations from the previous day's image are most likely not real.

chlorophyll concentration color scale
animation of 136 monthly chlorophyll composites over Micronesia

Monthly Aqua-MODIS chlorophyll composites: July 2002 through October 2013

A quick examination of SeaWiFS monthly composites (not shown) also reveals no features similar to the October 13, 2013 event. The SeaWiFS record extends back to September of 1997 when we first started collecting global ocean color data.