This dataset was produced using measurements extracted from the NASA SeaBASS database and collected during three Atlantic Meridional Transect cruises (https://www.amt-uk.org/) and it is described in more details in Graban et al., (2020). The dataset consists of chlorophyll-a concentrations estimated from particulate absorption coefficients (chl-ACS) using the line-height method (Boss et al., 2007) and de-biased using HPLC Total Chlorophyll data (chl-HPLC) as described in Graban et al (2020). The dataset also contains the latitude, longitude, UTC timestamp and the name of the research expeditions during which each point was collected. Finally, the dataset contains the collocated particulate beam-attenuation coefficients at 620 nm to 710 nm interpolated every 2 nm that were used in Graban et al. (2020). To allow the user to assess the accuracy of the chl-ACS data before debiasing, for each cruise separately we also provide plots of the comparison between line height (L=chl-ACS*0.014, see Eq 1 in the paper) and chl-HPLC, parameters and their 95% confidence intervals of the fit to the equation chl-HPLC = a*L^b, plots, median biases (\delta) and robust standard deviations (\sigma) of the relative residuals (i.e., chl-ACS/chl-HPLC-1), as well as the total number of points (N) used in the comparison. References E. S. Boss, R. Collier, G. Larson, K. Fennel, and W. S. Pegau, “Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR,” Hydrobiologia574, 149–159 (2007)." S. Graban, G. Dall'Olmo, S. Goult, and R. Sauzède (2020) "Accurate deep-learning estimation of chlorophyll-a concentration from the spectral particulate beam-attenuation coefficient" Optics Express, https://doi.org/10.1364/OE.397863