Validating A Bio-Optical Measurement Technique in the Northern Gulf of Alaska


Benjamin Lowin

Understanding the small- to large-scale patterns of photosynthetic carbon production by microscopic marine algae (termed primary production) in the ocean is of utmost importance for goals ranging from maintaining marine food webs, to healthy fisheries, to sustainable food resources for humans. This understanding is currently impeded in highly dynamic regions such as the Northern Gulf of Alaska (NGA) by limitations in on-station sampling capabilities for primary productivity. NASA Ocean Color Satellite imagery can provide estimates of phytoplankton biomass and productivity on time and space scales that far exceed any in situ measurement, but the algorithms used to generate these estimates are based on global data sets with relatively poor representation from high-latitude regions. Validation of satellite-based estimates for a given region requires the acquisition of high-quality matchups with accurate in situ measurements, which inherently requires that a high volume of in situ measurements be made. Current sampling methods yield approximately 30-50 measurements of primary productivity each year, which given persistent cloud cover and issues relating to sun glint, results in few to no satellite matchups. In my PhD project, I am employing a novel bio-optical approach that utilizes a vessel’s underway seawater supply to compile a range of biological estimates (including primary productivity) at sub-kilometer spatial scales. These data can resolve changes in biological properties across hydrographic frontal systems and eddies, oceanographic features thought to drive many of the observed patterns in primary production. Importantly, by providing continuous estimates during an entire oceanographic expedition, this method will vastly improve our ability to obtain the high-quality satellite matchups required to begin testing and validating NASA Ocean Color data products.


Name: Benjamin Lowin, Graduate Student

Institution: University of Alaska Fairbanks

Mentor: William Burt,

Award: Research Grant

Funding Period: 2021 to 2022