Experimental Approach
Our scientific objective has been to obtain time series profiles which document the vertical patterns of bio-optical distribution and variability in several coastal oceanic habitats. We have accomplished this objective by integrating newly developed bio-optical instrumentation with a CTD into a free-fall package that resolves physical, optical, and biological features over small vertical scales. The instrumentation package has an adjustable fall speed so that we can resolve vertical patterns on scales less than 10 cm. Typically, we adjust the buoyancy on the profiling package to provide 2-3 cm resolution of physical and bio-optical properties during each profile. Repeated profiles (approximately 10 per hour) provide the time series necessary to define the temporal patterns of persistence of small-scale features. The profiling package is designed so that the instrumentation configuration can be modified easily. During our work in East Sound in 1998, the deployment configuration consisted of a Sea-Bird 911 CTD, dual multi-wavelength absorption and attenuation meters (ac-9), a multi-wavelength spectrofluorometer which measures dissolved colored organic matter (SAFIRE), a data acquisition system (MODAPS), an Acoustic Doppler Velocimeter (ADV), and a rosette system for obtaining discrete samples during profiling (see figure above).
To accomplish our scientific objective, we completed an extensive collaborative field experiment in East Sound, Orcas Island, WA, during May and June 1998. We obtained over 400 profiles of small-scale bio-optical and physical structure under a range of forcing conditions. We applied our data merging protocols for multiple instruments on the profiling package (each instrument has a unique data acquisition rate) to obtain coincident physical and bio-optical data on the appropriate vertical scale. We recovered a thermistor chain that had been deployed for two weeks, providing resolution of physical forcing through internal wave energy. In addition, we monitored spectral upwelling radiance and spectral downwelling irradiance throughout the day with a tethered radiometric buoy.
Collaborators in this project include:
- Dr. Percy Donaghay, University of Rhode Island
- Dr. Jan Rines, University of Rhode Island
- Dr. Dian Gifford, University of Rhode Island
- Dr. Alice Alldredge, UC Santa Barbara
- Dr. Sally MacIntyre, UC Santa Barbara
- Dr. Mary Jane Perry, University of Washington
- Dr. Van Holliday, Tracor Systems
