Global distribution of photosynthetically available radiation on the seafloor.

A 21-year (1998-2018) continuous monthly data set of the global distribution of light (photosynthetically available radiation; PAR) reaching the seabed is presented. It uses ocean colour and bathymetric data to estimate benthic irradiance, offering critical improvements on a previous data set (Gattuso et al., 2006). The time series is 4 times longer (21 vs 5 years), the spatial resolution is better (pixel size of 4.6 vs 9.3 km at the equator) and the bathymetric resolution is also better (pixel size of 0.46 vs 3.7 km at the equator). The paper describes the theoretical and methodological bases and data processing. This new product is used to estimate the surface area of the sea floor where (1) light does not limit the distribution of photosynthetic benthic organisms and (2) net community production is positive. The complete data set is provided as 14 netCDF files available on PANGAEA ( https://doi.pangaea.de/10.1594/PANGAEA.910898 ). The R package CoastalLight, available on Github ( https://github.com/jpgattuso/CoastalLight.git ), allows (1) to download geographical and optical data from PANGAEA and (2) to calculate the surface area that receives more than a given threshold of irradiance in three regions (non polar, Arctic and Antarctic). Such surface areas can also be calculated for any sub-region after downloading data from a remotely and freely accessible server. [ABSTRACT FROM AUTHOR]