## 3 Results and Discussion
### CDOM, \(S_{g}\), and DOC Climatology
Bear in mind in this analysis that OC3M-like algorithms for retrieving Chl have been shown to be strongly influenced by not only phytoplankton biomass, but also physiology (particularly in tropical and subtropical regions) as well as the presence of significant absorption by CDOM and non-algal particulates (\(a_{dg}\)) [68]. The results show that over much of the world's oceans--particularly at high latitudes, upwelling zones, and regions influenced by large river plumes--normalized CDOM and Chl diverge by as much as a factor of three. Interestingly, the regions shown by [PERSON] et al. (2013) to be most negatively impacted by \(a_{dg}\) in terms of empirical Chl retrievals are the same regions which are shown here to diverge most strongly in terms of the normalized CDOM and Chl residual, indicating that a similar pattern would be expected even when using Chl retrieval algorithms less susceptible to error induced by \(a_{dg}\). The pattern that emerges is that in open ocean regions characterized by strong seasonal blooms such as the North Atlantic and North Pacific, high primary productivity in the presence of lower CDOM (i.e., high residual) is followed after approximately a season by higher CDOM and a collapse in Chl (i.e., low residual). This can be seen in the boreal Spring-Summer transition in the N. Atlantic and Pacific, in the bloom and collapse associated with the reversal of the monsoons in the Arabian Sea between Summer and the following Winter/Spring, and in the Congo and Amazon river plumes over the same period where the residual often shifts by approximately a factor of six between seasons. This observed seasonal lag between peak Chl and peak CDOM helps explain why the two properties rarely covary, as described above for GOCAD, and in [13]. The lag may be explained by the time required for microbial degradation of the bloom's less labile particulate detrital material after the bloom has collapsed. Application of these algorithms also shows the Spring-Summer transition in the CDOM absorption (left column, Figure 12) as an increase in CDOM from major river outflows such as the Amazon and Congo following peak runoff [69], and in the upwelling region of the Arabian Sea induced by the southwesterly monsoon. In the case of the Amazon River, the CDOM in the distal plume can be seen well into the following season as it drifts slowly eastward across the Atlantic from the retroflection of the North Brazil Current [70], indicating that satellite retrievals of CDOM using the MLR can successfully track surface DOM as it evolves over time scales of weeks to years and over very long distances. The results shown in Figure 12 are broadly similar to those described in [13] for CDM at 440 nm retrieved using the GSM algorithm [71], and to the empirical algorithm of [PERSON] [31] for \(a_{g}\)(350) (their Figure 12), although we show generally higher absorption across the equatorial regions and some parts of the Southern Ocean. Longer time-scale variability in the Aqua-retrieved CDOM was also apparent from the roughly twelve years of monthly, 4 km satellite composites. An examination of the monthly CDOM anomaly (\(\Delta a_{g}(\lambda)\); the monthly \(a_{g}(\lambda)\) divided by the Aqua-era averages for each month) and slope anomaly, \(\Delta S_{g}(\lambda)\), revealed several regions characterized by sharp declines in CDOM during certain years, and elevations in others, as well as the expected inverse proportionality between CDOM and slope in the UV. Figure 13 shows an example of this from seasonal Aqua composites of \(\Delta a_{g}(380)\) and \(\Delta S_{g}(275)\) averaged over periods of El Nino (2002-2005) when surface temperatures are higher, inhibiting vertical nutrient transport and leading to lower primary productivity, and periods of La Nina (2007, 2008, 2010, 2011), which exhibit roughly the opposite dynamics.