POSTER Session 1

Extracting inherent optical properties and depth profiles for Jerlov water types from the World-wide Ocean Optics Database

We have made new discoveries about Jerlov water types by using the World-wide Ocean Optics Database (WOOD), and we have open sourced our approach so others can apply it to their own research. Jerlov water types classify the world’s oceans by their near-surface clarity. They are quantified by their downwelling diffuse attenuation coefficient, Kd, but for some applications it is necessary to know the corresponding inherent optical properties – namely the absorption and scattering coefficients (a and b).We therefore turned to WOOD, which is a geographically diverse source of measured data for a range of ocean parameters. We grouped measured Kd data by time and location, and tagged them with the closest Jerlov water type. We then identified measured a and b data from the same time and location, which could adopt the same Jerlov tag. The result was a spectral profile of a and b for six Jerlov water types, significantly improving upon existing models. As the Jerlov water types are only defined in the first 10 meters of ocean depth, we also used a similar technique to characterise the typical depth profile of clarity for each Jerlov water type. We linked the Jerlov-tagged near-surface Kd measurements to Kd measurements taken at the same time and location but at deeper depths, down to 200 meters. Our approach can be applied to any of the 41 parameters within WOOD, and we have provided open access to our source code to allow others to apply it to their own applications.

Craig Williamson, Defence Science and Technology Laboratory (Dstl), United Kingdom, https://orcid.org/0000-0002-0115-0428

Richard Hollins, Defence Science and Technology Laboratory (Dstl), United Kingdom

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