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A. Valente et al.: A compilation of global bio-optical in situ data 
Earth Syst. Sei. Data, 8, 235-252, 2016 
www.earth-syst-sci-data.net/8/235/2016/ 
adg(443)/adg(490) 
adg(412)/adg(443) 
aph(490)/aph(443) 
aph(412)/aph(443) 
_dlb_ 
1 I 
i i ■ 
= 1 
: -kd- 
f- 
■ -HUH— 
1123 
1116 
1276 
1269 
0 0.5 1 1.5 2 2.5 3 3.5 4 
Figure 13. The distribution of absorption coefficient band ratios: 
adg(443) / adg(490), adg(412) / adg(443), aph(490) / aph(443) and 
aph(412) / aph(443). Data within 2nm of the wavelengths were 
used. The graphical convention is identical to Fig. 2. The vertical 
dashed lines show the lower and upper thresholds used for quality 
control in the IOCCG report 5 (IOCCG, 2006). The total number of 
points are divided between NOMAD (93-96 %), MERMAID (3- 
6 %) and SeaBASS (1%). 
Figure 14. Global distribution of observations of inherent optical 
properties (algal pigment absorption coefficient aph, débitai plus 
CDOM absorption coefficient adg and particle backscattering coef 
ficient bbp) in the final table. 
Figure 15. Global distribution of diffuse attenuation coefficient for 
downward irradiance (kd) per dataset in the final table. 
ness, an examination of bio-optical relationships is provided 
(Fig. 16). The relation between aph at 443 nm and chloro 
phyll a (Fig. 16a) agrees with the relation proposed by 
Bricaud et al. (2004). A total of 1070 points exist with these 
two variables available (93 % from NOMAD). The relation 
between the sum of aph and adg at 443 nm and rrs at 443 nm 
(Fig. 16b) shows a similar dispersion, with the exception 
of some scattered points, to an equivalent analysis on the 
IOCCG report 5 (see their Fig. 2.3). Again, the scattered 
data were retained in the final table to preserve the NOMAD 
dataset. A total of 1112 points exist for which these three 
variables are available (97 % from NOMAD). The relation 
between the ratio rrs(490) / rrs(555) and kd(490) (Fig. 16c) 
shows a good agreement with the NASA KD2S standard al 
gorithm (http://oceancolor.gsfc.nasa.gov/cms/atbd/kd_490). 
A total of 2280 points exist for which these three variables 
are available (93 % from NOMAD). The relation between the 
ratio rrs(490) /rrs(555) and bbp at 555 nm (Fig. 16c) shows 
a good agreement with the relation suggested by Tiwari and 
Shanmugam (2013). A total of 357 points exist for which 
these three variables are available (91 % from NOMAD). 
vations, from NOMAD (2266), SeaBASS (118) and MER 
MAID (70). Data distribution of kd at 44X and 55 A nm for 
each dataset is shown in Fig. 12g and h. No kd data at these 
wavelengths were available for the SeaBASS dataset (only 
at 490 nm). Median values of kd at 44X am span between 
0.08 m“ 1 (NOMAD) to 0.1m“ 1 (MERMAID), whereas at 
55X nm the kd values are approximately 0.1 m“ 1 (NOMAD 
and MERMAID). NOMAD provides the best geographic 
coverage (Fig. 15), with a higher coverage in the Atlantic, 
compared with other oceans. With the exception of the 
coastal regions of North America and the Japan Sea, most 
coastal regions are not sampled. In the Northern Hemisphere, 
kd is distributed roughly evenly across all months of the year, 
but in the Southern Hemisphere there are few data points dur 
ing the austral winter and none at all in September (Fig. 3). 
Although most of the stations with concurrent vari 
ables are mainly from the NOMAD dataset, for complete- 
4 Conclusions 
A compilation of bio-optical in situ data is presented in this 
work. The compiled data have global coverage and span from 
1997 to 2012, covering the recent period of ocean-colour 
satellite observations. They resulted from the acquisition, ho 
mogenisation and integration of several sets of data obtained 
from different sources. Minimal changes were made to the 
original data, except for those necessary for conversion to 
standard format and quality control. In situ measurements of 
the following variables were compiled: remote-sensing re 
flectance, chlorophyll a concentration, algal pigment absorp 
tion coefficient, detrital and coloured dissolved organic mat 
ter absorption coefficient, particle backscattering coefficient 
and diffuse attenuation coefficient for downward irradiance. 
The final set of data consists of a substantial number of in 
situ observations, available in a simple text table, and pro 
cessed in a way that could be used directly for the evaluation