Chlorophyll a: Source: Yoder, J. and Kennelly, M. (2005) "Live Access to US JGOFS SMP Data: Global SeaWiFS chlorophyll". http://usjgofs.whoi.edu/las?dset=Ocean+Color/Global+SeaWiFS+chlorophyll+1997-2004.SST: Source: ICOADS2° dataset (NOAA/OAR/ESRL PSD), http://www.esrl.noaa.gov/psd/data/gridded/data.coads.2deg.html.SSS: Source: Good, S. A., Martin, M. J., and Rayner, N. A. (2013) "EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates", Journal of Geophysical Research, Oceans 118: 6704-6716. UKMO EN4.0.2 analysis, http://www.metoffice.gov.uk/hadobs/en4/index.html.