Hyperspectraldownward sky leaving radiance observed at 45° zenith angle (Lsky) observed during RV METEOR cruise M187

Hyperspectral radiometric quantities were observed at a 5-minute sampling interval in the South Atlantic Gyre and Benguela Upwelling System during a scientific field campaign aboard research vessel (RV) Meteor. The research cruise began on January 25, 2023 from Walvis Bay, Namibia, and ended on March 01, 2023 in Walvis Bay, Namibia. A radiometer setup with one TriOS RAMSES-ACC hyperspectral cosine irradiance meter to measure incoming solar irradiance and two TriOS RAMSES-ARC hyperspectral radiance meters to measure total upward sea surface leaving radiance (Lsfc) at 45° nadir and sky-leaving radiance (Lsky) at 45° zenith angle, was installed using a custom-made frame at the bow of RV METEOR. Data logging of raw and calibrated radiometric quantities was automated using TriOS MSDA XE version 8.9.2 software. Further processing was done using R software (R Core Team (2023)). Processed data was interpolated to 1 nm spectral resolution using linear interpolation in R between 320 and 950 nm. Quality control involved retaining the Lsfc observations with lowest values (Garaba et al., 2012; Garaba et al., 2015) and corresponding Ed and Lsky observations. Raw data is available on request.