A. Valente et al.: A compilation of global bio-optical in situ data 
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www.earth-syst-sci-data.net/8/235/2016/ 
Earth Syst. Sci. Data, 8, 235-252, 2016 
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Figure 4. Ranges of remote-sensing reflectance band ratios 
(412 :443 and 490: 555) for all data. The points from the NOMAD 
dataset are shown in blue for reference. The total number of points is 
divided between MOBY (4513), AERONET-OC (17 293), BOUS- 
SOLE (3533), NOMAD (3120), SeaBASS (432) and MERMAID 
(677). To maximise the number of ratios per dataset, a search win 
dow of up to 12 nm was used when the four wavelengths (412, 443, 
490, 555 ) were not simultaneously available. The effect of different 
search windows was negligible in the ratio distribution. 
Figure 6. Comparison of coincident observations of chloro 
phyll a concentration derived with different methods (chla_fluor 
and chla_hplc). The data were transformed prior to regression anal 
ysis to account for their log-normal distribution. 
Figure 5. Global distribution of remote-sensing reflectance per 
dataset in the final table. The data sources are identified with dif 
ferent colours. Points show locations where at least one observa 
tion is available. Crosses show sites from where time series data of 
remote-sensing reflectance are available. 
Figure 7. Number of observations per chlorophyll a concentration 
acquired with different methods ( chla_fluor and chla_hplc). 
MERMAID (3711), ICES (5421), HOT (559) and AMT 
(164). The total number of chla_hplc observations is 13 918, 
ranging from 0.006 to 99.8 mg m -3 (Fig. 7), with contribu 
tions from NOMAD (1309), SeaBASS (5920), MERMAID 
(707), ICES (2994), HOT (153), GeP&CO (1536), BOUS 
SOLE (397) and AMT (902). The combined chlorophyll 
dataset (all chlorophyll data considered, but for a given sta 
tion HPLC data were selected if available) has a total of 
39 849 observations, with 11, 41 and 48 % from oligotrophic 
(<0.1mgm -3 ), mesotrophic (0.1-1 mg m -3 ) and eutrophic 
(> 1 mg m -3 ) waters, respectively. When compared with the 
proportions of the world ocean in these trophic classes, i.e. 
56 % oligotrophic, 42 % mesotrophic and 2 % eutrophic (An- 
toine et ah, 1996), oligotrophic waters are under-represented 
and eutrophic waters are over-represented in the compila 
tion. The combined chlorophyll dataset is evenly distributed 
between each month of the year in the Northern Hemi 
sphere, but in the Southern Hemisphere there are relatively 
few data points dining the winter months compared with 
the rest of the year (Fig. 3). The spatial distribution of the 
chlorophyll values for the combined dataset (Fig. 8) shows a 
good agreement with known biogeographical features, such 
as low chlorophyll values in the subtropical gyres and high 
values in temperate, coastal and upwelling regions. Many re 
gions show a good spatial coverage (e.g. Atlantic and Pacific 
oceans), while others are poorly sampled (e.g. Southern and