Program News

Physical Oceanography

Once again, the Physical Oceanography Program would like to thank the many people, both in the U.S. and abroad, who have taken the time to read proposals and provide us with thoughtful reviews. These reviews are crucial to the process of proposal evaluation and it is a tribute to our community that the return rate has consistently been above 80%, the highest in the Division of Ocean Sciences. The program would also like to thank this year’s panelists who, in the Spring or Fall, dedicated a substantial amount of time considering roughly 90 proposals.

Funding Highlights

The span of ocean science covered by recent proposals continues to be broad. Topics range from the dynamics of estuaries to the circulation of the abyssal ocean. The November 2001 panel also included 19 CLIVAR or CLIVAR-related proposals. One of the few remaining gaps in the synthesis of the WOCE data set was plugged with the funding of a pair of complementary proposals to analyze WOCE and historical hydrography around the Southern Ocean. Both projects will try to quantify exchanges between the Southern Ocean and the major ocean basins to the north as well as determining the circulation between the sub-basins of the Southern Ocean and the processes responsible for the creation of intermediate waters. One project will use classical hydrographic analysis techniques while the other will adopt a box inverse model approach.

Nearer to shore, the Program is collaborating with the Office of Naval Research to fund several investigators to participate in NCEX, the Near-shore Canyon Experiment, a major effort to push the understanding of near-shore processes in the presence of complex topography not captured in the various experiments at Duck, NC. Other near-shore research funded includes the use of video imagery of the surf zone to determine information about both the circulation and the bathymetry, and the analysis of data from a rip-current system on a barred beach. Studies within the coastal zone also include an examination of eddies produced by tidal flow past headlands and an investigation of river plumes.

Major field projects funded over the last year include several related to inter-basin exchanges. One tackles the formation and transformation of deep and intermediate waters in the Nordic Seas. In the South Atlantic, a new field experiment is aimed at quantifying the transport of Indian Ocean waters by Agulhas eddies using in-situ and satellite observations. Over in the Indian Ocean, several oceanographers will try to establish whether there is a sustained Agulhas undercurrent. Another significant field effort is an attempt to obtain direct estimates of isopycnal dispersion using very accurately ballasted RAFOS floats.

In 2001, the PO program has continued its commitment to the collection of long time-series data off Bermuda and Hawaii. Such time-series can be expensive and difficult to maintain for decades. It is anticipated that over the next two years, the physical and biogeochemical components of HOT will become more tightly coordinated. It is hoped that the optimization of the data collection schedule and the use of new technologies will lead to greater efficiency and a reduction in the overall cost. A desire for additional time-series sites is clear in community planning documents. If the number of long time-series sites is to expand without severely compromising the program’s ability to fund other types of research, the per site cost must become more manageable. In the past year or so, the program has seen proposals to begin sustained time-series efforts in several other locations. These have been expensive proposals and the reviewers have wanted to see a careful explanation of the scientific payoffs, reassurance that the site location and experimental design will meet the scientific objectives, instrumentation and manpower pared to what is essential for the task, and a commitment to making the data collected freely and rapidly available (the HOT and BATS programs are excellent examples in this regard). The program would also like to see some indication of a long-range plan for maintaining these time series after their start-up phase.

What do Program Directors do when they’re not reviewing proposals?

Most people know of the program’s role in managing the review of new proposals and making funding recommendations. Some will have seen us during site visits, often in conjunction with Program Officers from ONR or a nearby workshop, or at national meetings such as Ocean Sciences. On these occasions we try to broaden our sense of people’s research directions, get to know young scientists starting their independent research careers, listen to feedback about NSF and/or the proposal review process, and try to answer whatever questions we can.

A less visible role is the one we play in trying to secure new funding for ocean science and in promoting both disciplinary and interdisciplinary opportunities for new science. In this we draw heavily upon the white papers and planning documents prepared by the community. Internally, we act as advocates for programs developed by the research community. We are frequently asked for input on new Foundation-wide and inter-agency initiatives and contribute to strategic planning documents. We serve as Program Directors for inter-agency competitions like NOPP and the large NSF-wide competitions such as Biocomplexity in the Environment (BE) and Information Technology Research (ITR). For the ocean science community, these competitions are becoming increasingly significant opportunities for funding outside of the core programs and ocean scientists have had noticeable success within them. Ocean researchers who have not yet proposed to ITR or BE are encouraged to investigate the lists of funded awards from previous year competitions, as well as abstracts, available on the NSF web pages. Last, we liaise with a number of advisory and steering committees established by the research community; for example, CLIVAR, Ocean Carbon Research and Ocean Information Technology Infrastructure.

CLIVAR/Carbon Cycle

The Program continues to fund climate-related research and, with the recent emergence of detailed CLIVAR implementation plans, anticipates a growth in the number of CLIVAR and CLIVAR-related projects. Our initial emphasis will be the implementation of the components of the ACVE plan dealing with the mid- to high-latitudes in coordination with the developing ASOF and NERC’s ACCE programs, as well as pilot studies to examine the role of low latitude boundary currents in Pacific climate variability, a critical component of the P-BECS plan. In the near future, Global Change research will include significant efforts in the study of the carbon and hydrological cycles. For more information about the recent announcement of opportunity for carbon cycle research, see the chemical oceanography program news.

Staffing

Several personnel changes will greet us with the New Year. Dr. Bill Wiseman will return to LSU this winter after a two-year tour of duty, taking with him a great knowledge of estuarine and coastal systems and a wicked sense of humor. We will miss the challenging scientific discussions we have had on a daily basis around morning coffee about priorities and future directions in our field and wish him well. The Physical Oceanography Program anticipates welcoming on board two new faces in 2002. Dr. Theresa Paluszkiewicz who managed the Ocean Modeling program at ONR for the past four years will join us as Program Director in a permanent slot in January of 2002 and we are negotiating with a second person who should join the program as a rotator in the Summer of 2002. Both are experienced and well-respected scientists and we expect a smooth transition.

Eric Itsweire (eitsweir@nsf.gov)
Bill Wiseman (wwiseman@nsf.gov)
Steve Meacham (smeacham@nsf.gov)

The Hawaii Ocean Mixing Experiment: Survey Field Phase
Contributed by Rob Pinkel, SIO

The Hawaii Ocean Mixing Experiment is a five-year NSF program to study tidally induced ocean mixing in the vicinity of the Hawaiian Ridge. The Experiment is divided into five programs, including Historic Data Analysis, Modeling, Survey, Farfield and Nearfield components. The Analysis and Modeling efforts began in 1999, with the objective of identifying locations along the Ridge where the barotropic-baroclinic conversion process was strong and mixing was likely. Guided by these efforts, the Survey observational program conducted a reconnaissance of the Ridge from August 2000 through January 2001. The objective was to identify sites of intense internal tide generation and strong mixing. Scientists from the University of Washington, Oregon State University, University of Hawaii and Scripps Institution of Oceanography, UCSD participated.

The Absolute Velocity Profiler being deployed from the R/V Wecoma. Photo courtesy of J. Nash, University of Washington.

How much mixing might one expect to find? The over-all tidal energy budget for the Ridge includes three principal terms: the energy lost from the surface tides, the energy radiated away as baroclinic (internal) tides, and the energy lost to mixing processes near the Ridge. Recently, using TOPEX Poseidon data, Egbert has estimated the barotropic energy loss to be of order 20 GW (from the M2 tide alone). Present estimates (satellite derived) of the baroclinic flux are of order 10-15 GW, leaving 5- 10 GW available for mixing. The HOME Farfield Experiment began in the Spring of 2001 to provide an accurate in-situ estimation of the radiated baroclinic flux.

The Surveyors identified sites of intense barotropic to baroclinic conversion near French Frigate Shoals, Nihoa Island and in the Kauai Channel west of Oahu. Mixing levels were enhanced in these regions, with eddy diffusivities approaching 10-3 m2 s-1 in the bottom quarter of the ocean, up to distance of order 10 km from the Ridge (Gregg, Moum, Sherman). Shear and strain were elevated above open ocean background levels to 50-100 km off the Ridge axis (Rudnick, Pinkel). Preliminary estimates suggest that the total dissipation in this farfield “glow” might be comparable to the energy loss in the much smaller region of intense nearfield mixing.

Extremely large (300 m) amplitude internal tides of cnoidal form were observed above the topography of the Kauai Channel. It was found that the Princeton Ocean Model implemented by Merrifield and Holloway was extremely successful in identifying the sites of strong barotropic-baroclinic conversion and in quantifying the radiated low mode internal wave energy. Their POM model predicted three sites of strong baroclinic tide generation along the Ridge, the Kauai Channel, Nihoa Island and French Frigate Shoals. Measurements by Sanford, Kunze, and Lee corroborated the model predictions. The internal tide generation process and the associated cascade of energy to mixing scales will be the focus of the coming Nearfield Experiment (August-November 2002).