Global particulate matter pool temporal variability over the SeaWiFS period (1997–2007)

[1] Major patterns of temporal variability associated with marine particulate backscattering coefficient at 490 nm (bbp(490), an indicator of the particulate organic carbon concentration) and particle backscattering spectral dependency γ (a proxy for the relative proportion between small and large particles) are investigated with a 10-year SeaWiFS series. Generally, the contribution of the seasonal cycle to the series variance has a similar spatial pattern for γ and the chlorophyll a concentration (Chla). The spatial distribution of significant monotonic changes for γ and Chla (reaching up to ±5% yr−1) is also comparable with opposite signs of the slope, indicating that inter-annual changes in Chla and average particle size are often positively correlated. Conversely, spatial patterns of seasonality and trend found for bbp(490) often differ from those of Chla and γ. Particularly, large seasonal signals for bbp(490) are seen poleward of 45° while high seasonality for Chla and γ is found in two mid-latitude zonal belts (∼20°–40° latitude). Significant changes in bbp(490) over the considered decade are much fewer and usually not significant in areas where strong positive or negative changes in Chla have been detected. This suggests that the changes in phytoplankton have not been translated in terms of overall particle stock.