The three-component model is often used to invert the phytoplankton size class (PSC) concentration globally, especially in open oceans. Limited by the three-component model’s assumption, new efforts were made to explore PSC in different water environments. Mass global cruise data sets were gathered and classified into coastal, mixed, and open ocean data sets depending on the variation in bathymetric depth. A new power three-component model was established for coastal water samples (<50 m), where the determination coefficient (R2) were 0.99, 0.51, and 0.38 for micro- (Micro), nano- (Nano), and picophytoplankton (Pico), respectively. We also updated the coefficients of the exponential three-component model in open ocean (>200 m) and found that the PSC verification results performed better in the north of −40°N oceans (R2: 0.83, 0.70, and 0.64, respectively). A smooth function for the samples in mixed ocean waters (50–200 m) was designed to obtain PSC by different weights between the power and exponential three-component models with relatively low accuracy (R2: 0.84, 0.37, and 0.14, respectively), indicative of the complex conditions in these regions. We assessed the published models’ performance in coastal and open ocean samples and found an apparent underestimation of the Nano and Pico chlorophyll concentrations when their concentrations were larger than 0.2 mg m-3. The PSC proportion distribution was consistent with existing knowledge. This study evaluated the preliminary consideration of the assumption of the exponential three-component model and found that it may fail in the South Ocean, based on the global open ocean data set.

The packaging effect of phytoplankton pigments is sometimes capable of accounting for over half of the variability in the phytoplankton absorption coefficient (aph) in oceanic waters. Given the significance of aph in many marine biogeochemical and environmental processes, exploring the packaging effect on absorption properties thus becomes a crucial task. In the present study, two pigment compensation models for quantifying the packaging effect are developed for Case I and Case II waters, respectively, based on high-performance liquid chromatography (HPLC)-derived pigments and aph data from the NOMAD and the marginal seas of China. As a critical quantity in developing our models, phytoplankton “missing” absorption is derived by subtracting the reconstructed aph without the packaging effect from the measured aph. Our proposed models use the established relationships between “missing” absorption and specific absorption coefficients of pigment groups without the packaging effect to quantify pigment group concentrations. Validation using independent in situ data sets demonstrates that great improvements are achieved for the quantification of the packaging effect, especially for waters under abnormal packaging effect conditions. Applying the proposed models to satellite data displays the spatial distributions of the packaging effect in the Atlantic Ocean and the marginal seas of China, as delegates of Case I and II waters, respectively. The generated spatial distribution demonstrates a rule that the packaging effect intensity positively covaries with chlorophyll-a distribution. The findings of this study exhibit a capability of mapping a spatial distribution of the packaging effect from satellite observations for the first time.