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Optical properties are complex representing variable contributions of phytoplankton, Colored Dissolved Organic Matter (CDOM), marine and atmospherically derived non-algal particles. The relative contributions of these are particularly complex for enclosed inland seas such as the Mediterranean. It is critical to collect regional ocean color data from satellites which must be complemented with spatial subsurface measurements. The development of autonomous platforms outfitted with a range of physical/optical sensor packages offer great potential. Slocum Coastal Gliders make an ideal platform when coupled with the appropriate optical sensor suite. The utility of the Glider has lead to the development of Glider Operations Center (GOC) which allows operators anywhere in the world to remotely control and visualize Glider data which can also be easily merged with numerical model data outputs and/or remote sensing imagery (Fig. 1).
Glider data will address the importance of atmospheric dust in the Mediterranean. The importance of atmospherically derived nutrients has been shown and its role to marine ecology and productivity has been frequently hypothesized. For example, in the Mediterranean, dust from the Sahara (Fig. 2) and northern European countries is hypothesized to account for up 15% of the new production and up to 14% of the total primary production in the Mediterranean; however documenting deposition and its relationship to primary productivity over the time (weeks to months) and space (100-1000 of kilometers) scales that these processes operate has been difficult. This has forced workers to rely on remote sensing; however these approaches are susceptible to the presence of dust which mimics the presence of phytoplankton in the satellite imagery. Ocean color algorithms use remote-sensing reflectance to estimate the concentration of chlorophyll a. In very clear waters the presence of dust can impact the accuracy of the empirical algorithms. Given this, is the ocean signal associated with atmospheric dust related to the stimulated phytoplankton productivity or is it simply the dust itself? We must quantify the impact of dust on both the in situ optical properties and biological communities over relevant spatial (100 kms) and temporal (month) scales in oligotrophic waters.
Given these interests we will in this project:
- use a fleet of Webb Gliders to provide a regional subsurface physical and optical dataset to support ship-based NASA, NATO, and ONR efforts being conducted in the Mediterranean in autumn 2008 and spring 2009,
- coordinate the activities of a fleet Gliders outfitted with a variety of sensors to quantify the physical hydrography of the coastal and offshore waters in the Mediterranean,
- demonstrate a web-based GOC for Gliders with fleet control being transferred between operators on the ship, personnel at the NATO facility at La Spenzia, and scientists & students in United States throughout the month long experiment and,
- use data to understand physical and optical dynamics in the Mediterranean with a focus being on understanding the relative importance of atmospherically derived sub-micron dust particles and phytoplankton to determining the derived satellite data products.
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 Fig. 1 A SeaWiFS visible image capturing Saharan dust transported to the Mediterranean. The dust appears as the brown haze over the Mediterranean.
Fig. 2 Visualizations from the Glider GOC, providing a real-time
command control combined with advanced visualization capabilities.
A) A merged SST satellite, CODAR, and MURI sponsored Glider line. Capabilities also now exist to merge model outputs.
 B) Fleets of Glider data visualized in the GOC visualizer.
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