J. Kohut

The Long-term Ecosystem Observatory: an integrated coastal observatory

An integrated ocean observatory has been developed and operated in the coastal waters off the central coast of New Jersey, USA. One major goal for the Long-term Ecosystem Observatory (LEO) is to develop a real-time capability for rapid environmental assessment and physical/biological forecasting in coastal waters. To this end, observational data are collected from satellites, aircrafts, ships, fixed/relocatable moorings and autonomous underwater vehicles. The majority of the data are available in real-time allowing for adaptive sampling of episodic events and are assimilated into ocean forecast models. In this observationally rich environment, model forecast errors are dominated by uncertainties in the model physics or future boundary conditions rather than initial conditions. Therefore, ensemble forecasts with differing model parameterizations provide a unique opportunity for model refinement and validation. The system has been operated during three annual coastal predictive skill experiments from 1998 through 2000. To illustrate the capabilities of the system, case studies on coastal upwelling and small-scale biological slicks are discussed. This observatory is one part of the expanding network of ocean observatories that will form the basis of a national observation network.

Stratified coastal ocean interactions with tropical cyclones

Hurricane-intensity forecast improvements currently lag the progress achieved for hurricane tracks. Integrated ocean observations and simulations during hurricane Irene (2011) reveal that the wind-forced two-layer circulation of the stratified coastal ocean, and resultant shear-induced mixing, led to significant and rapid ahead-of-eye-centre cooling (at least 6 °C and up to 11 °C) over a wide swath of the continental shelf. Atmospheric simulations establish this cooling as the missing contribution required to reproduce Irenes accelerated intensity reduction. Historical buoys from 1985 to 2015 show that ahead-of-eye-centre cooling occurred beneath all 11 tropical cyclones that traversed the Mid-Atlantic Bight continental shelf during stratified summer conditions. A Yellow Sea buoy similarly revealed significant and rapid ahead-of-eye-centre cooling during Typhoon Muifa (2011). These findings establish that including realistic coastal baroclinic processes in forecasts of storm intensity and impacts will be increasingly critical to mid-latitude population centres as sea levels rise and tropical cyclone maximum intensities migrate poleward.

Data Management and Real-time Distribution in the HF-Radar National Network

The architecture, status and applications of a realtime data access, distribution, processing and storage system designed for networking radial data from surface current mapping HF-Radar instruments across the United States is presented. By leveraging the system design of HF-Radar sites, data access is generalized to nearly all sites while still providing alternate access options where needed. Data format convergence, while not required, is achieved for data from all systems through careful metadata mapping and code development. Object ring buffers (ORBs) and ORB communication protocol provide robust and flexible data transport while a relational database facilitates data storage. The HF-Radar Network has evolved from a prototype project to an operational status over the last 2.5 years with 4 data access sites (portals) and 1 data aggregation site (node) deployed. By early 2007, an additional portal and 2 additional nodes will be added to create a distributed network. To date, the repository contains over 356,000 radial files produced by 45 sites from 10 participating institutions. Recent development has focused on real-time total vector processing on a national scale. Base grids for the U.S. West and East/Gulf Coast of 1 km nominal resolution extending 300km offshore are created using an equidistant cylindrical projection. A community standard MATLAB toolbox for total vector processing is optimized for production on large grids and integrated into the real-time system to produce hourly surface current maps on a national scale at 1 km, 2 km and 6 km resolutions. Current applications of the HF-Radar network include an interactive radial diagnostic site for use by site operators and a prototype interactive web site providing the first images of realtime surface currents integrated across a national scale

Mapping the Mid-Atlantic Cold Pool evolution and variability with ocean gliders and numerical models

During the summer, distinctive, bottom-trapped, cold water mass called the Cold Pool resides over the mid to outer continental shelf in the Middle Atlantic Bight (MAB); strongly influencing parts of the ecosystem including important fisheries. Since 2003, repeated ocean glider temperature and salinity (TS) water property measurements along a seaward transect from the coast of New Jersey have helped to define the important variability in the cross-shelf structure of the Cold Pool there. To develop forecast capability, we need to better understand the relevant processes that control Cold Pool seasonal evolution and variability. To do this, we are now beginning to integrate ocean glider TS measurements with data assimilation models for the purpose of generating prototype Cold Pool forecast maps; with important support from the Mid-Atlantic Regional Association Coastal Ocean Observing System (MARACOOS). Here we report recent progress in having models assimilate zig-zag, along-shelf glider measurements of the Cold Pool. This years 2012 measurements are revealing a shelf and Cold Pool water, which appear to be as much as 1°C warmer than in previous years.

Coastal Ocean Observatories Enable Biological Investigations in a Buoyant Plume

Rivers that flow through urban watersheds represent major conduits for the transport of anthropogenically derived nutrients and chemical contaminants to the coastal ocean. The fate of these materials is controlled not only by the physical dynamics of the riverine plume as it moves over the coastal shelf, but also by associated biological and chemical processes. The resulting interactions are complex and often difficult to capture using traditional oceanographic methods and resources. The advent of coastal observation systems, however, enables ocean scientists to react quickly and adaptively sample dynamic coastal environments to more fully understand key physical, chemical and biological processes. In April 2005, during the Lagrangian Transport and Transformation Experiment (LaTTE), nutrient-laden water discharged from the Hudson River was retained nearshore in a recirculating eddy before moving southward along the New Jersey coast and mixing with relatively saline coastal water. Biological sampling of the recirculating zone and southward moving plume water was facilitated by a shelf-wide coastal observatory system. Rapid nutrient uptake and assimilation by phytoplankton within the eddy resulted in extremely high rates of productivity (> 10 mg C m-3 h-1). Approximately 75% of the fixed carbon within the eddy could be attributed to phytoplankton in the > 20 um size class determined subsequently to be comprised primarily of large (~200 um) chain forming diatoms. Characterization of the zooplankton assemblage revealed a dominance of small copepods, approximately 200-400 um in size, and shipboard grazing experiments indicated a negligible feeding impact of these mesozooplankton on the phytoplankton. The apparent mismatch in size between producers and consumers, coupled with the high rates of primary production, resulted initially in a pronounced accumulation of phytoplankton biomass (>25 ug L-1 chl a) within the recirculation zone with subsequent declines in dissolved oxygen concentration in bottom waters coincident with nutrient reduction and bloom senescence

Using Webb gliders to maintain a sustained ocean presence

Buoyancy driven Slocum gliders were a vision of Douglas Webb, which Henry Stommel championed in a vision published in 1989. Slocum gliders have transitioned from a concept to a technology serving research and environmental stewardship. The long duration and low costs of gliders allow them to anchor spatial time series. Large distances, over 600 km, can be covered using a set of alkaline batteries. Lithium batteries can anchor missions that are thousands of kilometers in length. Since the initial tests, a wide range of physical and optical sensors have been integrated into the glider allowing measurements of temperature, salinity, depth averaged currents, surface currents, fluorescence, apparent/inherent optical properties active and passive acoustics. A command/control center, entitled Dockserver, has been developed that allows users to fly fleets of gliders simultaneously in multiple places around the world via the Internet. Since October 2003, Rutgers gliders have conducted 157 missions, traversed >55,000 kilometers, logged >2600 days at sea, and logged ~350,000 vertical profiles. The capabilities of the glider make them an indispensable tool for the growing global effort to build integrated ocean observatories. For example, gliders are now a central tool within the National Science Foundation Ocean Observatory Initiative (OOI) and the National Oceanic and Atmospheric Administrations Integrated Ocean Observing System (IOOS). Gliders provide a new magnet in which to attract young people into the ocean science and engineering. For example Rutgers undergraduates now anchor long duration flights of gliders world-wide beginning their freshmen year. This is critical to training the next generation.

Studying the Dynamics and Biological Significance of the Hudson River Using an Ocean Observatory

The Lagrangian Transport and Transformation Experiment (LaTTE) was designed to quantify how physical, biological and chemical processes transform material in a buoyant river plume and to link these processes to wind forced changes in the plume structure. The three LaTTE field programs include a May 2004 pilot, a full scale effort in April 2005, and a final study planned for May 2006. In each field study, dye is released and tracked by two vessels for physical, biological and chemical sampling of the tagged water mass. The field study and data assimilation segments of LaTTE rely on a research-based coastal ocean observatory to provide a temporal and spatial context for these intensive process studies. The observatory includes a shelf-wide observational backbone (international satellites, nested HF Radars, and autonomous underwater gliders) that was locally enhanced with high-resolution relocatable moorings in the New York Bight apex for the process studies. During the experiments, a shore based operations center combined real-time datasets with forecasts from a high-resolution atmospheric model (WRF) and hindcasts from an ocean model (ROMS) to provide adaptive sampling guidance to the research vessels. Results from the April 2005 pilot and the May 2006 process study will be reviewed. During the strong outflows of April 2005, the ebb tide squirts flowing onto the shelf were observed to respond to a strong sea breeze, forming a recirculating eddy just south of the Harbor entrance. The eddy served as an incubator for biological productivity, resulting in high phytoplankton concentrations leading to depleted bottom dissolved oxygen in a location consistent with historical observations. Only a portion of the fresh river water entering the recirculation zone exited as the expected coastal current along the New Jersey shelf. Most of the freshwater was observed to flow cross-shelf along the southern flank of the Hudson Shelf Valley, consistent with historical remote sensing data. This newly observed transport pathway can have potentially significant impacts on material transport from the Hudson River plume onto the continental shelf. In 2006, wind driven circulation resulted in the plume advecting south along New Jersey and eventually detaching into two pieces. In 2006, wind driven ROMS forecasts were successful at predicting the transport of the river as validated by the drifters and glider data

Educational needs in the changing field of operational oceanography: training the people that will sustain Munk's 1+1 = 3 scenario

The Rutgers University Graduate Program in Oceanography (GPO) has initiated a new Masters Degree in Oceanographic Technologies. Within the collaborative setting of the Rutgers University (R.U.) Coastal Ocean Observation Labs (COOL) Operations Center, students will receive hands-on training in the use of advanced ocean observing technologies and will participate in the year-round field activities supported by the Center. Potential Masters, theses topics include improvements to the capabilities of sensors and sampling platforms, and the analysis of the observatory datasets for a wide spectrum of applications. The program was designed with input from a pair of AMS Interactive Workshops on Operational Oceanography, and with input from people working in Navy and NOAA operational centers. Graduates will directly support the sustained technology needs of the Integrated Ocean Observing System and the Ocean Observation Initiative.

Observed response of the Hudson River plume to wind forcing using a nested HF radar array

One objective of the Lagrangian Transport and Transformation Experiment (LaTTE) is to determine the relative advantages of studying the Hudson River plume within the spatial and temporal context provided by an operational research observatory. Towards this end, a shelf-wide observational backbone was locally enhanced with high-resolution relocatable systems in the New York Bight apex. The permanent backbone includes local acquisition of international satellite ocean color imagery, a network of long-range High Frequency radars, and a cross-shelf Endurance line occupied by an autonomous underwater glider. The high resolution systems, including higher resolution HF Radar, glider and mooring networks, were moved to the New York Bight Apex to support the specific interdisciplinary process study. During the LaTTE field effort, datasets from the nested observation network, including a triple nested HF Radar array, were assembled in real-time at a shore-based acquisition center, and high-resolution atmospheric forecasts were performed. Surface current observations will be reviewed, with specific emphasis placed on the observed response of the Hudson River plume to local winds. The observatory results provide a spatial and temporal context for viewing the LaTTE dye release, chemical and biological results.

The growth of the New Jersey Shelf Observing System for monitoring plumes and blooms on the Mid-Atlantic continental shelf

To study changes occurring within the Mid-Atlantic Bight (MAB), we have constructed a shelf-wide ocean observatory. While initial efforts focused on using an undersea cable, our experience during a series of coastal predictive skill experiments demonstrated that spatial data were the most highly valued commodity. Because of this we have focused on developing a subsurface capability to mirror the existing satellite and HF radar capabilities. Currently in situ spatial data are collected with a fleet of autonomous underwater Sloccum Gliders to collect physical and biooptical data throughout the year. Our scientific efforts have focused on understanding biogeochemical dynamics on the MAB. Topographic steering of currents and its impact on material transport on the MAB plays a central role in transporting material from the nearshore to offshore slope waters. Additionally hypoxia and anoxia dynamics in the coastal MAB appear related to offshore dynamics. Gliders provide ideal platforms for tackling those problems.