An AUV-Based Investigation of the Role of Nutrient Variability in the Predictive Modeling of Physical Processes in the Littoral Ocean
Abstract
Our long-term goal is to explore and test the potential effectiveness of low-level nutrient concentrations (nitrate, nitrite, and ammonia) as descriptors of geophysical fields and tracers of physical processes in oligotrophic coastal waters, with particular attention to adapting our laboratory sensor for these nutrients for use in an AUV. The nutrient data are to be incorporated into prognostic physical-biogeochemical models in a feedback mode. The first objective was to modify the AUV nutrient sensor to improve detection limits and reliability. We expected important progress toward a final version that will have detection limits acceptably close to those of our high-sensitivity laboratory version: ~5 nanomolar (Masserini and Fanning, 2000a). The second objective was to compare nutrient distributions in the field obtained by the laboratory and AUV versions of the nutrient sensor package. The comparison would be conducted on the West Florida Shelf in the area designated as the ECOHAB Control Volume in order to relate the results to our regular nutrient surveys in the region and to physical circulation measurements made by USF currentmeter moorings. The third objective was to perform high-sensitivity nutrient surveys with the laboratory version of our nutrient sensor package at the same time and in the same waters as surveys of sulfur hexafluoride (SF6), which would be injected at a site in the Control Volume near one of the moorings in the center of the USF array. Out of this work was expected to come comparisons of concurrent distributions and spatio/temporal trends of nutrients and SF6. Ultimately, dispersion coefficients determined using surficial changes in nutrient concentrations might be compared to those obtained from SF6 concentration changes. The fourth objective was to investigate the effects of turbulence and stratification in different seasons on the nutrient/ SF6 comparisons.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 2000
- Accession Number
- ADA609559
Entities
People
- John Walsh
- Kent A. Fanning
Organizations
- University of South Florida