Monthly average non-algal Supended Particulate Matter concentrations

Spatially gridded, monthly average of non-algal Suspended Particulate Matter (SPM). Based on satellite derived Ifremer OC5 algorithm (Gohin et al. 2011). Interpolated and merged data from SeaWiFS, MODIS, MERIS and VIIRS satellite sensors.

Based on Gohin et al. (2005) OC5 algorithm that jointly estimates the load of Chlorophyll and non-algal suspended particulate matter. This algorithm has been validated against in-situ coastal observations for the English Channel and Bay of Biscay (Gohin, 2011) and modified to merge multiple sensors (Saulquin et al. 2011): SeaWiFS from 1998-2002; MODIS + MERIS, January 2003-March 2012 and MODIS + VIIRS from April 2012 to the present.

The daily products generated from multiple sensors and interpolated to 1.1 km were extracted from ifremer’s ftp site: ftp://ftp.ifremer.fr/ifremer/cersat/products/gridded/ocean-color/atlantic/EUR-L4-SPIM-ATL-v01/. The data extends from 13°W to 12°E and 36°N to 60°N. This covers the continental shelf in UK waters to the exception of the Faroe-Shetland channel North of 60°N.

The daily images of non-algal SPM from 1/1/1998 to 31/12/2015 were averaged into 12 monthly means for the 18 years (216 fields). These were used to calculate a climatological average (Figure 7) as well as a climatological monthly averages (see Appendix A). The yearly anomaly was calculated as the difference between the yearly average and the climatological mean (see Appendix B).

The several satellites have been cross calibrated but caution should be used when comparing average values from SeaWiFS (1998-2002) with more modern sensors (Gohin, pers. comm.).