Large scale surveys
Large-scale studies of biogeochemical variables in the ocean
are sparse. Extant views describe an ocean which is heterogeneous
on many scales with the greatest part of the variance at low spatial
and temporal frequencies. Unfortunately these large time and space
scales have not been well observed in the ocean. The rationale
for the large scale survey component is to provide a composite,
basin to global scale, biogeochemical view of the ocean surface,
mid-depth and deep waters. During the JGOFS implementation phase
specifically we planned to provide seasonal resolution of key
biogeochemical parameters on regional and basin scales and to
provide a consistent global description of surface pigment, primary
production, CO2 and export fluxes and transformations.
The large scale survey of oceanic CO2 parameters conducted as part of the WOCE Hydrographic Program (WHP) cruises is a major component of the survey mode program element. U.S. scientist's contributions to this effort have included so far many WOCE lines in the Pacific, Indian, Southern and Atlantic oceans. The U.S. contribution to the WHP global survey is presently scheduled to be completed by the end of 1997.
The other major large scale effort was to be the ocean color sensor Sea-Viewing Wide Field Sensor (SeaWiFS). Despite many plans for deployment of this instrument it was not launched in time for the major US JGOFS Process Studies. It may be launched in spring 1997. The failure to have remotely sensed ocean color data has been a real disappointment to the program.
Major process studies
Early on in JGOFS it became clear that many of the links between
key biogeochemical parameters were not well understood. The objective
of the process studies component has been to target key process
links in our current models of the oceanic biogeochemical system
and enhance our causal understanding of the processes. The goal
of process oriented studies is to provide a mechanistic understanding
of ocean processes in sufficient detail to predict and simulate
biogeochemical fluxes at representative sites in the ocean.
Following the initial JGOFS pilot study of the spring bloom in the North Atlantic in 1989, the U.S. carried out a major process study in the Equatorial Pacific in 1991-92. The study had a principal focus on the N/S line at 140W and included both survey and time-components. But a sub-set of the cruises was organized to collect larger scale data on several N/S sections both east and west of 140W. In addition, area overflights by a NASA P-3 aircraft provided further larger spatial scale observations of surface ocean properties around the area surveyed by the surface vessels. The first post-cruise workshop was held in July 1993 in Seattle. Further discussions of the scientific results from this study were held at the AGU/ASLO Ocean Science meeting in San Diego in February 1994 and at the Oceanography Society meeting in Honolulu in July 1994. The latter followed a major synthesis and data evaluation workshop which was held in Scottsdale, Arizona in June 1994. About 90 research papers from the EqPac Process Study will be contained in three special issues of Deep-Sea Research, two of which are already published. Details can be found in the US JGOFS Home Page at http://usjgofs.whoi.edu/eqpac.html
U.S. JGOFS completed a major process study in the Arabian Sea for about sixteen months from late 1994 until early 1996. These cruises provided seasonal coverage of the annual monsoon and inter-monsoon cycles in the area south east of Oman - from where the cruises were staged. In addition to the NSF supported program in the Arabian Sea, both ONR and NASA had programs which were well integrated with the NSF plans. These plans were made in the wider context of international JGOFS plans for this region and in collaboration with WOCE cruises scheduled for this region. The first Arabian Sea Data Workshop was held in July 1996 at the University of New Hampshire and a further large data synthesis meeting is planned there in July 1997. Many preliminary data presentations have been made in special sessions at recent national meetings.
The U.S. JGOFS Antarctic Environment and Southern Ocean Process Study (AESOPS) began field work on August 29, 1996 and will continue through April of 1998. This study has been jointly funded by the Division of Polar Programs and the Division of Ocean Sciences at NSF. It is a two ship campaign, with the ice edge work being handled by the R/V Nathanial B. Palmer and the frontal zone work planned for the 1997-98 austral summer on R/V Roger Revelle. It was planned that the U.S. JGOFS Southern Ocean program would include a strong and active modeling component that allows for the development and implementation of many levels of modeling effort. Some pre-fieldwork modeling studies were initiated following a joint announcement of opportunity from NSF to support US JGOFS and US GLOBEC Southern Ocean modeling studies. This study completes the US JGOFS program of Process Studies.
Time-series sites
Prior to JGOFS there were no long term biogeochemical time
series in the oceans. As US JGOFS enters its final phase, we now
have close to two ten-year records (Hawaii
and Bermuda).
Resource limitations dictate a limited number of such time series
sites. Such limitations also suggest that future time series efforts
will utilize autonomous observing systems rather than human/ship
mediated observations. The objective of the time series effort
is to provide well-sampled seasonal resolution of biogeochemical
variability at a limited number of ocean observatories, provide
support and background measurements for process-oriented research,
as well as test and validate observations for biogeochemical models.
Data collected at the Bermuda and Hawaii sites on regular ship visits and permanent moorings allow assessment of oligotrophic ocean variability of parameters affecting the ocean carbon system on a range of time-scales. A suite of JGOFS core measurements has been made at these sites since their inception in 1988. These data have provided new insights on the seasonal and interannual variability of ocean carbon system parameters there. The Planning Office has made these data available through publication of hard copy reports and electronic access information. A Deep-Sea Research Special Volume with 24 papers by scientists working at the Bermuda and Hawaii sites was published in 1996.
Synthesis and Modeling
The U.S. JGOFS Synthesis and Modeling Project (SMP) will be
launched this summer at a workshop on the role of oceanic processes
in the global carbon cycle. To be held July 27 - August 2 in Snowbird,
Utah, the workshop will bring together empiricists and modelers
for a week of intense discussion on how to achieve the central
JGOFS goals of characterizing the processes controlling oceanic
carbon fluxes on a global scale and predicting the responses of
oceanic biogeochemical processes to anthropogenic perturbation.
The main legacy of this component of U.S. JGOFS will be the synthesis of knowledge gained from field and modeling studies into a set of models that reflect our current understanding of how oceanic processes affect the global carbon cycle. Attaining this goal will be neither simple nor straightforward, requiring as it must the synthesis and modeling of knowledge gained from the global survey of carbon dioxide (CO2) in the ocean, the time-series programs at Hawaii and Bermuda, the U.S. process studies in the North Atlantic, equatorial Pacific, Arabian Sea and Southern Ocean, and JGOFS studies conducted by our international partners.
Modeling represents the synthesis of our process understanding as well as an approach for testing our current understanding of various biogeochemical cycles. With sufficient development, models can be used to examine sampling strategies for process studies as well as large scale observations. In the near term, models also suggest possible linkages where improved understanding will provide the greatest advantage. U.S. JGOFS views models in all these ways, however, our objective is to provide a useful synthesis of our understanding which can be used for diagnosis of the current ocean role in the carbon system, as well as for future forecasts of the ocean state.
Modeling efforts supported directly through the U.S. JGOFS program have been rather limited. Some modest model studies were made in advance of all the major process studies to help define issues and priorities for the field programs. Until FY 1996, only about 3% of U.S. JGOFS funds were used for model studies. Now that the field programs are winding down, this situation has begun to change dramatically. A major new initiative, the U.S. JGOFS Synthesis and Modeling (SMP) project has been started Its central objective is to synthesize knowledge gained from U.S. JGOFS and related studies into a set of models that reflect our current understanding of the ocean carbon cycle and its associated uncertainties. Emphasis will be given to processes that control partitioning of carbon among oceanic reservoirs and the implications of this partitioning for exchange between the ocean and atmosphere. The first of several Announcement of Opportunities for support of SMP projects was issued by NSF in early 1997 and the level of support is expected to ramp up into a major ongoing effort to crystallize the advances in understanding of the ocean carbon cycle through US JGOFS. In anticipation of this, support of synthesis activities began through the US JGOFS Planning Office during the last grant cycle. Support was provided for major data and synthesis workshops for the Equatorial Pacific and Arabian Sea Process Studies - and will be continued for the Southern Ocean Study. Production and dissemination of Special Issues of Deep-Sea Research was supported for Time-Series and Equatorial Pacific research and synthesis papers. The first annual major SMP workshop was held in August 1996 in New Hampshire and a second one is planned for August 1997 (emphasizing Time-Series Synthesis). A Synthesis and Modeling Steering Committee, headed by Jorge Sarmiento and Scott Doney, was set up by the US JGOFS Steering Committee to provide the necessary oversight and guidance to the SMP program. They will act in a manner analogous to the Process Studies coordinators who provided the leadership for each study.
Data Management
Until 1994, U.S. JGOFS depended on the interim data management
scheme handled by George Heimerdinger, Northeast Liason Officer
of the NOAA/NODC field office in Woods Hole whose services have
been generously loaned to U.S. JGOFS by NODC. Then a new approach
to project data management was initiated with NSF support to implement
the object-oriented distributed data system developed by the U.S.
JGOFS Data Management Group. A Data Management Office (DMO) was
established and funded in Woods Hole which is providing a permanent
and flexible system of data handling. U.S. JGOFS has made significant
progress since June of 1994, when Christine Hammond joined our
staff The DMO has successfully teamed up Chris' technical skill
with the data management experience of George Heimerdinger.
The adoption of the World Wide Web's httpd as the server utilized by Glenn Flierl's object-oriented distributed data system marked the beginning of increased acceptance of the U.S. JGOFS approach. We see this as a flexible and increasingly useful system which will meet the demands of Principal Investigators for easy access to JGOFS data, and will adequately handle the huge volume of data currently and soon to be generated.
A full account of the rational and strategy for the DMO is laid out in chapter 6 of the US JGOFS Mid Program Strategy (http://usjgofs.whoi.edu/strategy6.html). Rapid progress has been made thanks to the energy and skill of Chris Hammond who is the head of the DMO. Jointly developed to meet the needs of US JGOFS and US GLOBEC data management, the DMO is presently acting as a very effective project data management system. The Web-based interface has been very effective at both making information available and providing access to the data system. All data from the North Atlantic Bloom Experiment and the Equatorial Pacific Process Study are now publically available on line. Arabian Sea data - previously accessible just to the P.I. group involved in the study - are now in the process of entering the public domain. Southern Ocean Process Study data sets will enter the system in like manner. Links to the Time-Series, Carbon Dioxide and International JGOFS data sets are in place. Now that the first objective of making the datasets easily and rapidly available has been achieved, more effort is now underway to make the system as useful as possible to the user base by improving the data organization, on-line tools etc. At the same time, and coordinated nationally and internationally, the ultimate archiving plans for US JGOFS data sets will be determined. It is likely that this will involve both NODC archiving responsibilities and the production of selected CD-ROM sets.