Presenter: Jinghui Wu (Lamont Doherty Earth Observatory at Columbia University)

Description:
For the past three decades, polar-orbiting ocean color satellites have afforded the means to obtain local, regional to global scale estimates of oceanic net primary production that have greatly aided studies on ocean carbon cycling, food web dynamics and climate change. Despite considerable progress, the full potential of ocean color satellites to provide accurate estimates of daily ocean productivity has not been realized because polar-orbiting satellites are unable to account for variations in carbon fixation rates that are caused by changing incident irradiance levels over the course of the day. Here for the first time, we have attempted to exploit the unique short-temporal measurements possible by the Korean Geostationary Ocean Color Imager (GOCI), to obtain hourly measurements of surface- and euphotic-column integrated Net Primary Productivity (NPP). These estimates are based on the Absorption Based Productivity Model (AbPM) and are advantaged by a comprehensive bio-optical database of photo-physiological rate parameters measured at different times of the day during the Korea-US (KORUS) cruise in May-June 2016. Limited on-deck photo-physiological rate estimates that varied across different water types encountered around the Korean Peninsula were scaled using dynamic optical-biogeochemical (O-BGC) provinces. Daily and weekly integrated NPP satellite estimates of NPP compared against in-situ measurements, clearly underscore the superiority of geostationary over polar-orbiting ocean color satellites, which stems from their ability to account for short-term changes in phytoplankton light absorption and incident irradiance fields that fluctuate greatly over the course of the day.