From Sailors to Satellites: A Curated Database of Bioluminescent Milky Seas Spanning 1600-Present

Milky seas are a rare, historically fabled form of marine bioluminescence. Characterized by their steady, non-flashing, eponymous white glow; milky seas are capable of illuminating over 100,000 ${\text{km}}^2$ of the nocturnal ocean surface for months at a time. Eyewitnesses have compared the experience of sailing through a milky sea to a snowy plain at night, the “Twilight Zone,” and even the biblical apocalypse. Despite centuries of scientific research into milky seas very little is known about the physical and biogeochemical processes which govern their formation, longevity, and size. Scientific inquiry into milky seas has historically been held back due to the paucity of data, and the remote, ephemeral nature of the phenomenon. Through combining centuries of first-hand eyewitness accounts with modern satellite-based low-light imagers such as the Day/Night Band we present the first extant database of milky sea eyewitness accounts in over 30 years. We also present the first statistical comparison between milky seas and coupled atmosphere-ocean phenomena such as the El Niño Southern Oscillation and the Indian Ocean Dipole to elucidate connections between milky seas and potential sources of predictability within the coupled earth system.