f2964575-indicator-ocean-chlorophyll-concentrations-seawifsmodisa-process

The file used to make the image was created from ~300 individual NetCDF SeaWiFS/MODIS-A monthly data files. Each file was a monthly average grid of values-by-year (1998-m01, 1998-m02, ... , 1998-m03, 1999-m01, ..., ) at 9 km resolution. These (9km) were translated into 1/4-degree (~25 km) resolution to create a single annual average value (all months for all years). Some higher latitude areas have less than 12 months due to winter data loss (Alaska and higher). SeaWiFS data are used for 1998 to 2001. SeaWiFS and MODIS-A data are averaged together during years when both datasets exist: 2002 to 2010. MODIS-A data are used for 2011 to 2014. For the map, data plotted are for the time range January 1, 1998 to December 31, 2014. For each regional bar chart, percent differences were calculated between the annual average concentration and the 1998-2012 average concentration for the region, over the period 1998 to 2014. Trend lines were calculated. The data was accessed March 27, 2015.

This activity resulted in the following :

• image f2964575-7891-4cc8-85d0-92f9518b72f6 was derived from dataset MODIS Aqua Level 3 Global Monthly Mapped 4 km Chlorophyll a
• image f2964575-7891-4cc8-85d0-92f9518b72f6 was derived from dataset SeaWiFS Global Monthly Mapped 9 km Chlorophyll a