A. Valente et al.: A compilation of global bio-optical in situ data 
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”kd NOMAD ® kd SeaBASS ® kd MERMAID ® tsm COASTCOLOUR ® tsm MERMAIF 
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Figure 15. Global distribution of diffuse attenuation coefficient for downward irradiance (“kd””) and total suspended matter (“tsm’””) per 
data set in the final table. The “tsm”” and “kd” points from MERMAID overlap each other in west Black Sea (- 40° N, 30° E) and Arctic 
(70° N. 120° W). 
MAID and SeaBASS). The relation between the sum of 
“aph” and “adg” at 443 nm and “rrs” at 443 nm (Fig. 16b) 
shows a dispersion similar, except for some scattered points, 
‘Oo an equivalent analysis on the IOCCG report 5 (IOCCG, 
2006; see their Fig. 2.3). Again, the scattered data were re- 
:ained in the final table to preserve the NOMAD data set. 
A total of 1112 points exists for which these three vari- 
ables are available (97 % from NOMAD). The relation be- 
:ween the ratio rrs(490) / rrs(555) and kd(490) (Fig. 16c) 
shows a good agreement with the NASA KD2S standard 
algorithm (https://oceancolor.gsfc.nasa.gov/atbd/kd/, last ac- 
cess: 18 December 2022). A total of 2280 points exists for 
which these three variables are available (93 % from NO- 
MAD). The relation between the ratio rrs(490) / rrs(555) and 
“bbp” at 555 nm (Fig. 16c) shows a good agreement with the 
‚elation suggested by Tiwari and Shanmugam (2013). A to- 
tal of 365 points exists for which these three variables are 
available (89 % from NOMAD). 
4 Data availlabilitv 
Information about the data availability can be found in Ap- 
pendix B. 
5 Summary and conclusions 
In this work, a compilation of bio-optical in situ data is 
presented, resulting from the acquisition, homogenization, 
and unification of several sets of data obtained from differ- 
ent sources. The compiled data have a global coverage and 
span the period from 1997 to 2021, which corresponds to 
che period of a continuous satellite ocean colour data record. 
Minimal changes were made on the original data, other than 
conversion to standard format. data reductions in time and 
attos://doi.org/10.5194/essd-14-573 /-2UZ, 
space, and quality control. In situ measurements of the fol- 
lowing variables were compiled: remote-sensing reflectance, 
chlorophyll-a concentration, algal pigment absorption coeffi- 
cient, detrital and coloured dissolved organic matter absorp- 
tion coefficient, particle backscattering coefficient, diffuse at- 
tenuation coefficient for downward irradiance, and total sus- 
pended matter. 
The final set of data consists of a substantial number of 
in situ observations, available in a simple text format, and 
processed in a way that is used directly for the evaluation 
of satellite-derived ocean colour data. The major advantages 
of this compilation are that it merges six commonly-used 
data sources in ocean colour validation (MOBY, BOUS- 
SOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID), 
four data sources developed for ocean colour applications 
(AWI, COASTCOLOUR, TPSS, and TARA), and 17 ad- 
ditional sets of chlorophyll-a concentration data (AMT. 
ICES, HOT, GeP&CO, ARCSSPP, BARENTSSEA, BATS, 
BIOCHEM, BODC, CALCOFTI, CCELTER, CIMT, ESTOC, 
[MOS, MAREDAT, PALMER, SEADATANET) free of du- 
plicated observations. This data set was initially created with 
the intention of evaluating the quality of the satellite ocean 
colour products from the ESA OC-CCI project, but it can 
also be used for other purposes, including the validation of 
retrievals from recent satellite missions such as Landsat 8 
and Sentinel 2. It may also be useful in the preparation of fu- 
ture sensors like NASA PACE. In addition, it is likely one of 
the largest collections of chlorophyll-a concentrations ever 
assembled, making it useful for the climate and biological 
scientific communities. The objective of publishing the com- 
pilation is to make it easily accessible for the broader com- 
munity. 
In comparison with previous versions, the main advan- 
tage of the present version (version 3) is that it includes 
more recent data (especially from 2016 onwards). These new 
Earth Syst. Sei. Data, 14. 5737-5770. 2022