Two stations were visited in the western tropical Pacific Ocean: The South-East Asia Time-series Station (SEATS) in the northern South China Sea (SCS) and station F2 in the Philippine Sea, ~230 km to the northeast of the Luzon Strait. Water samples were taken aboard the R/V Dong-Fang-Hong 2 in July and August 2017 from 13 depths between 5 m and 3800 m at SEATS and 11 depths between 5 m and 3200 m at F2 using Niskin bottles mounted on a SeaBird 911 conductivity-temperature-depth (CTD) rosette sampler. Lab irradiation experiments of samples from different sampling depth were carried out. The samples were irradiated for 6 days under a SUNTEST XLS+ solar simulator equipped with a 1.5 kW xenon lamp and a special UV filter to remove radiation at wavelengths <290 nm. The samples before and after irradiation were defined as 'unirradiated samples' and 'irradiated samples', respectively. This table lists the chemical and optical properties of dissolved organic matter at different sampling depth before and after 6-d irradiation.