A Multi-Spectral Thermal Infrared Imaging System for Air-Sea Interaction Research

Recent research has shown that physical interactions between the earth's atmosphere and ocean are inadequately described by purely windspeed-based parameterizations. In contrast to wind flow over flat surfaces, the ocean surface prominently features waves that form, grow, interact with each other, and eventually break. In the course of this process, the waves alter the turbulent properties of the airflow near the surface and thus change how the atmosphere and ocean exchange momentum and energy. While this effect has been studied extensively in the laboratory and through numerical modeling, it is exceptionally difficult to observe, and therefore quantify, in the real ocean. To address this fundamental knowledge gap, a multi-spectral thermal infrared imaging system will be developed during this project. This novel device will enable the previously-unavailable real ocean observation of viscous (i.e., molecular-scale) stress and heat transfer in the uppermost layer of the sea without disrupting the flow, a task previously relegated to the controlled laboratory setting. These 21st-century measurements will yield crucial insight into basic air-sea transfer processes, thereby directly improving the way in which atmosphere-ocean interactions are treated in weather and climate models.

This project will develop a multi-spectral infrared imaging system which is capable of measuring in detail the vertical profile of turbulent features in the aqueous viscous sublayer. This will enable the direct non-invasive measurement of the water-side tangential stress and temperature profile (i.e., heat flux), which would be transformational measurements to make in the real ocean. This system will be subjected to extensive validation in a controlled laboratory environment against industry-standard reference measurements, allowing for the careful determination of error sources and limits of application. When it is completed, it will be capable of installation and operation on fixed tower, ship, and airborne platforms. The data produced by this system are fundamental for the development of a comprehensive air-sea flux framework and the validation of models which forecast weather, waves and regional and global climate change. The proposed work includes the designing, building, calibration, and testing of the instrument over a two-year period.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.