Development and Field Deployment of a Novel AUV Gravimeter
Dr. James Kinsey
Gravity measurements can provide valuable information about the density and porosity of the sub-seafloor structure and provide crucial additional constraints on the shallow oceanic crustal structure. Gravity anomalies are routinely measured from ships and satellites. However, the large distance between the gravimeter and the seafloor precludes using this approach for resolving small-scale and low amplitude density anomalies and motivates employing autonomous underwater vehicles (AUVs) to obtain near-bottom gravity measurements.
Presently, there is no gravimeter suitable for use on an AUV. This proposal investigates using a new class of accelerometers to develop and test a new AUV gravimeter. This new sensing capability will augment and enhance the instrumentation already on the Sentry AUV and motivate new investigations in using gravimetry to improve our understanding of the shallow oceanic crust.
This project is co-funded by the Deep Ocean Exploration Institute.
Helicopter Measurements at the Edge of Greenland?s Outlet Glaciers
Dr. Fiammetta Straneo, Paul Fucile & Glenn McDonald
We will develop a compact system to collect temperature and salinity profiles using existing expendable probes from a helicopter. The system will have the added flexibility of being used from a small boat, or from the ice. This system will be used to make measurements at the edge of outlet glaciers in Greenland which are inaccessible by boat because of the dense iceberg pack and, typically, do not allow landing a helicopter, because of the instability of the ice pack.
The goal is to understand the glacier/ocean coupling in Greenland and the physical processes which control the rate of submarine melting. The motivation is provided by the rapid mass loss that is occurring in Greenland and by the hypothesized role of the ocean as a driver of change.
The long-term goal of this project is to design a system that is sturdy and simple enough to be operated by local personnel for cost-effective monitoring. This work takes advantage of an existing NSF project to conduct field work in one major SE Greenland glacier/fjord system and our goal is to develop it and utilize it summer and winter 2011 and 2012.
Investigating Gross Primary Productivity in the South Pacific Gyre
Dr. Rachel Stanley
The South Pacific Gyre is a fascinating area of the ocean because it has the lowest chlorophyll and the clearest waters on earth, leading to suggestions that it might be the least productive region in the ocean. However, intriguing initial studies have suggested that gross primary productivity –a measure of the total amount of photosynthesis and thus the base of the food chain – may be comparable in the South Pacific Gyre as in many other ocean regions. This begs the question of how is the carbon cycle functioning in the South Pacific Gyre? Unfortunately, the gyre is so remote that only a few studies have been done in these very interesting waters.
With Access to the Sea funding, I will take advantage of a cruise of opportunity to measure two innovative gas tracers – triple oxygen isotopes and oxygen/argon ratios – in order to constrain biological productivity in the South Pacific Gyre. Measurements of the tracers in the surface water will allow us to investigate the factors controlling productivity in this unique region of the ocean. Measurements of triple oxygen isotopes deep in the water column will allow us to investigate whether photosynthesis is occurring in waters traditionally thought too deep for photosynthesis.
Test Deployment of Long-endurance Microstructure Sensors on a Spray Glider
Dr. Jong Jin K Park, Dr. Louis St. Laurent & Dr. W. Brechner Owens
Turbulent mixing near eddies and fronts is an intermittent process, which requires sustained measurements so that the significant mixing events are sampled. Turbulent mixing can be estimated using a microstructure package that measures temperature, conductivity, and velocity at the one centimeter scale. Installing a microstructure profiling module (microRider-1000) from Rockland Scientific (http://rocklandscientific.com/microRider/tabid/78/Default.aspx) on the Spray ocean glider (http://www.whoi.edu/instruments/viewInstrument.do?id=1498) will enable us to make long-endurance microstructure measurements. This integration is underway using separate internal WHOI funding. This grant is to make a set of three deployments of the new micro-structure Spray glider to provide an engineering test of the system and then to acquire some scientific data on the New England continental shelf and near the shelf break current to demonstrate the utility of this new system.
The first engineering test deployment will be carried out in the vicinity of the Martha’s Vineyard Coastal Observatory (MCVO). The second deployment will be carried out in conjunction with the drifter experiment carried out by I. Rypina under another Access to the Sea grant. The third deployment will be near the shelf-break south of Martha’s Vineyard where the OOI Pioneer Array will be located and will measure mixing near the Shelf-Break Front. Upon the successful completion of these deployments, we will have the necessary data sets to demonstrate the utility of this new system, which can then be used in externally funded programs to investigate mixing in the vicinity of strong eddies and fronts.
Near-surface Drifter Experiment to Uncover the Lagrangian Template of Stirring on the Inner Part of the Continental Shelf Near Martha?s Vineyard Coastal Observatory
Dr. Irina Rypina
Stirring and water mass exchange processes across the inner part of the continental shelf have a major influence on the sediment distribution, nutrients concentrations, and the hydrographic structure of the inner shelf.
However, the exceptionally complex spatially-variable, depth-dependent dynamics of the inner shelf makes it difficult to characterize and quantify these exchanges using conventional techniques. Dynamical systems theory, which lies halfway between the deterministic and the stochastic description of the flow, provides a way to reduce this complexity by picking out specific structures from the body of complicated underlying fluid parcel motions, which guide water dispersal over time. These structures, which are called Lagrangian Coherent Structures (LCSs), form a natural template or “Lagrangian skeleton” for stirring in the ocean.
This proposal requests funds to carry out a one-time deployment and subsequent recovery of a set of 100 GPS-tracked ClearSat Davis-type near-surface drifters with 1-meter sails at the inner part of the continental shelf near Martha’s Vineyard Coastal Observatory, and to pay the associated data telemetry charges.
The resulting drifter tracks will be used to map out LCSs and uncover the Lagrangian skeleton of stirring on the Martha's Vineyard inner shelf.
Coral Tissue Sampling Cruise-of-Opportunity in the South China Sea
Dr. Konrad Hughen
Coral reefs around the globe are under increasing threat from the impacts of climate change and anthropogenic activities. The ability to assess coral health and identify potential sources of stress is needed to protect and conserve coral reefs. Current assessments of coral reef health are carried out by visual inspection, although at the molecular level, corals and their symbionts can display stress before external signs and symptoms become visible. Recent research at WHOI has resulted in the development of novel indicators of coral stress based on the lipids produced by symbiotic algae. However, in order to apply molecular stress indices from culture experiments to in-situ corals, extensive field sampling is required. Quantitative information is needed about the natural baseline variability of molecular profiles in healthy coral populations of multiple species, and molecular stress indices must be validated against in-situ corals experiencing known stress. Field sampling efforts on a global scale are limited by the complex logistics of sampling and transporting coral tissues for detailed biochemical analysis, including permitting for work with corals (endangered species) and logistics of obtaining and maintaining liquid nitrogen in remote tropical locations.
This award will be used to join a coral research cruise of opportunity to the South China Sea, in order to collect tissue samples from healthy and diseased corals. I am collaborating with Dr. Nathalie Goodkin of Hong Kong University in a research program funded to obtain coral drill cores from throughout the South China Sea, together with research institutions in Vietnam, Philippines and Malaysia. Through this award, I will join a coral drill-coring cruise to Vietnam in the winter of 2011, as an opportunity to obtain frozen coral tissue samples. This cruise will involve extensive preparations for logistics, as gear will have to be shipped to the Vietnam site, and permits for returning coral samples will have to be already in place, and thus presents a unique opportunity to obtain samples that would otherwise not be possible. This research will contribute to the development of new indicators of coral and symbiont stress based on lipid molecular markers. Such new tools could be employed rapidly and efficiently to assess coral health and identify stress before signs and symptoms are otherwise visible.