Optical Variability in the Ocean

Prediction of the optical properties of the upper ocean is of central importance in oceanography. These properties regulate the reflection from and the penetration of visible radiation in the sea with important ramifications for physical and biological oceanographic processes as well as planetary climate changes. For example, the ocean is "dark" as compared to the terrestrial surface, and the solar radiation absorbed in the upper layers heats and stabilizes the ocean. Variability in the rate of attenuation of visible radiation consequently plays a strong role in the development of upper ocean thermal structure and dynamics. A fraction of the absorbed radiation is responsible for driving the photosynthetic process on which life in the sea, and many chemical transformations, depends. For applied interests, the attenuation of visible wavelengths dictates the effective transmission from point and diffuse sources either at the sea surface, or at depth. The goals of my research program are to examine both the sources of variability in ocean optical properties, and to evaluate the effect of this variability on both oceanic biogeochemical cycles and physical climate interactions. Specific objectives include first the elucidation of the sources of variability in the optical properties of the ocean. These include biological processes, fluid dynamical processes (particularly turbulence), nonliving, but optically active ocean constituents (e.g. bubbles), and the physical properties of the radiance field as influenced by the atmosphere, air-sea interface, and the net effects of radiative transfer within the ocean interior. Second, I plan to evaluate the role of variability in oceanic optical properties in determining rates of primary production in the sea, particularly on scales appropriate for the determination of the role of oceanic biogeochemical processes in the global carbon cycle. Thirdly, we will evaluate the role of variability in oceanic optical properties in determining the thermal structure and dynamics of the upper ocean. A particular focus will be on the development of appropriate autonomous observation systems and sensors for the observation of ocean optical properties at scales that will be useful for the numerical prediction of the evolution of the upper ocean physics, chemistry and biology.