Attenuation coefficient of usable solar radiation of the global oceans

TitleAttenuation coefficient of usable solar radiation of the global oceans
Publication TypeJournal Article
Year of Publication2016
AuthorsLin J.F, Lee Z., Ondrusek M., Kahru M
JournalJournal of Geophysical Research-Oceans
Volume121
Pagination3228-3236
Date Published2016/05
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000383466500023
Keywordscolor; irradiance; matter; models; natural-waters; optical-properties; par; sea; surface
Abstract

Usable solar radiation (USR) represents spectrally integrated solar energy in the spectral range of 400-560 nm, a domain where photons penetrate the most in oceanic waters and thus contribute to photosynthesis and heating at deeper depths. Through purely numerical simulations, it was found that the diffuse attenuation coefficient of downwelling USR (K-d(USR), m(-1)) is nearly a constant vertically in the upper water column for clear waters and most turbid waters. Subsequently an empirical model was developed to estimate Kd(USR) based on the diffuse attenuation coefficient at 490 nm (Kd(490), m(-1)). We here evaluate this relationship using data collected from a wide range of oceanic and coastal environments and found that the relationship between Kd(490) and Kd(USR) developed via the numerical simulation is quite robust. We further refined this relationship to extend the applicability to "clearest" natural waters. This refined relationship was then used to produce sample distribution of Kd(USR) of global oceans. As expected, extremely low Kd(USR) (similar to 0.02 m(-1)) was observed in ocean gyres, while significantly higher Kd(USR) (similar to 5.2 m(-1)) was found in very turbid coastal regions. A useful application of Kd(USR) is to easily and accurately propagate surface USR to deeper depths, potentially to significantly improve the estimation of basin scale primary production and heat fluxes in the upper water column.

DOI10.1002/2015jc011528
Short TitleJ Geophys Res-Oceans
Student Publication: 
No