Bioluminescence in a complex coastal environment: 1. Temporal dynamics of nighttime water-leaving radiance

Nighttime water‐leaving radiance is a function of the depth‐dependent distribution of both the in situ bioluminescence emissions and the absorption and scattering properties of the water. The vertical distributions of these parameters were used as inputs for a modified one‐dimensional radiative transfer model to solve for spectral bioluminescence water‐leaving radiance from prescribed depths of the water column. Variation in the water‐leaving radiance was consistent with local episodic physical forcing events, with tidal forcing, terrestrial runoff, particulate accumulation, and biological responses influencing the shorter timescale dynamics. There was a >90 nm shift in the peak water‐leaving radiance from blue (∼474 nm) to green as light propagated to the surface. In addition to clues in ecosystem responses to physical forcing, the temporal dynamics in intensity and spectral quality of water‐leaving radiance provide suitable ranges for assessing detection. This may provide the information needed to estimate the depth of internal light sources in the ocean, which is discussed in part 2 of this paper.