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The Southern Oce Convergence and f the Antarctic f the Pack Ice
SOUTHERN OCEAN DYNAMICS A Strategy for Scientific Exploration 1973-1983 Ad Hoc Working Group on Antarctic Oceanography Panel on Oceanography Committee on Polar Research National Research Council NATIONAL ACADEMY OF SCIENCES [\j/\$-NAt Washington, D.C. 1974 MAY 2 41974 LIBRARY
NOTICE: The project which is the subject of this report was approved by the Governing Board of the National Research Council, acting in behalf of the National Academy of Sciences. Such approval reflects the Board's judgment that the project is of national importance and appropriate with respect to both the purposes and resources of the National Research Council. The members of the committee selected to undertake this project and prepare this report were chosen for recognized scholarly competence and with due consideration for the balance of disciplines appropriate to the project. Responsibility for the detailed aspects of this report rests with that committee. Each report issuing from a study committee of the National Research Council is reviewed by an independent group of qualified individuals accord- ing to procedures established and monitored by the Report Review Com- mittee of the National Academy of Sciences. Distribution of the report is approved, by the President of the Academy, upon satisfactory completion of the review process. Available from Committee on Polar Research 2101 Constitution Avenue Washington, D.C. 20418
Committee on Polar Research James H. Zumberge, Chairman Robert A. Helliwell, Vice Chairman: Antarctic Keith B. Mather, Vice Chairman: Arctic D. James Baker, Jr. E. Fred Roots James R. Barcus Jay T. Shurley William S. Benninghoff Rupert B. Southard, Jr. Charles R. Bentley Norbert Untersteiner Colin B. Bull A. Lincoln Washburn Sayed Z. El-Sayed Wilford F. Weeks William W. Kellogg Louis DeGoes, Executive Secretary Panel on Oceanography D. James Baker, Jr., Chairman Warren W. Denner Worth D. Nowlin, Jr. Theodore D. Foster Ferris Webster Dennis E. Hayes Ad Hoc Working Group on Antarctic Oceanography D. James Baker, Jr., Chairman Arnold Gordon Terry E. Ewart Worth D. Nowlin, Jr. Theodore D. Foster Ferris Webster 1971 Ad Hoc Study Group on Antarctic Oceanography (responsible for draft of December 1971) Kenneth L. Hunkins, Chairman S. G. H. Philander D. James Baker, Jr. Henry Stommel Theodore D. Foster H. van Loon Adrian E. Gill Bruce Warren Stanley Jacobs Wilford F. Weeks William D. McKee L. Valentine Worthington iii
Foreword The Committee on Polar Research (CPR) was asked by the National Science Foundation (NSF) to undertake a series of discipline-oriented studies on antarctic research. Each was to include a 10-year plan of investigation that was compatible with anticipated logistic, operational, and fiscal constraints. As background, the Committee was provided with a variety of operational and logistical alternatives, along with their estimated costs, that might be developed over the next 10 to 20 years. In his letter to the Committee, Joseph 0. Fletcher, Head of NSF's Office of Polar Programs, stated: Our objective in Antarctica is to support the most fruitful scientific program. Our long range operational requirements and logistic plans must be based on clear delineation of scientific problems and identification of the most promising approaches for solving them. We need your help to do this. For example, a few operational alternatives that depend on evaluation of scientific needs are: 1. Shall we continue to develop facilities at McMurdo Sound and Christchurch, our bases of operations during the past 15 years, or will future scientific needs call for operational capabilities in areas too far from McMurdo for operational support (such as the Weddell Sea)? If so, we need to start now to prepare for these needs. (For example, the location of Siple Station is determined by its conjugacy to a Canadian station and the proximity of their magnetic field line to the plasma- pauseâbut Siple Station is closer to South America than to McMurdoâ where will the next conjugate pair be?) 2. Should we close down the facilities in the Antarctic Penin- sula (Palmer Station and R/V Hero), continue activities at the present level, or undertake more ambitious activities there? (R/V Hero could probably be more intensively utilizedâespecially in winter.) 3. Should we invest in a refit and modernization of the USNS Eltanin in 1974 or retire her? 4. What will be our requirements for icebreaker support in 1980? (This is a question of current urgency.) 5. Should we continue a pattern of intense summer operations and winter hibernation or develop capabilities for all season operations? What kind of operations? Why?
vi Foreword 6. Will our future scientific needs be met by fixed stations and present methods of field party support, or should we actively develop mobile or transportable laboratories, employing vehicles such as the hovercraft? 7. With our operational capability centered at the Ross Sea, a number of programs have developed that are directly related to the presence of the large ice shelf: mass budget and deformation, ice shelf drilling, sub-shelf heat and mass budget, sub-ice-shelf biota, bottom water formation, sediment cores. Do we want eventually to continue these studies in the Ronne Ice Shelf region? If so, when and where?" In accepting this challenge, the Committee was mindful that the cost of logistic support for implementing polar research is exceptionally high because of the remoteness, inaccessibility, extreme cold, and extended periods of daylight and darkness. Accordingly, the Committee gave con- siderable emphasis to the acquisition of useful data by automatic stations, to include unmanned geophysical observatories, buoys, aircraft, balloons, rockets, and space vehicles. In developing its reports, the Committee looked upon the antarctic region as an integral part of total global environment and, whenever possible, related its recommendations to the objectives of on-going international worldwide research programs such as the Global Atmospheric Research Program (GARP), the International Decade of Oceanic Exploration (IDOE), and the Deep Sea Drilling Project (DSDP). The Committee called on each of its discipline-oriented panels to prepare studies as proposed. The outcome is a series of reports, each of which focused on one of the particular disciplines: glaciology, oceanography, meteorology and climatology, geology and solid-earth geophysics, upper- atmosphere physics, and biology. Outside experts were called in as required, and each of the reports was reviewed by concerned groups within the Na- tional Academy of Sciences and the National Research Council. This is one of the series of such reports. The Committee intends to review and update these studies periodically, as advances and developments dictate. This approach deviates somewhat from that taken in developing the report, Polar Research: A Survey (National Academy of Sciences, Washington, D.C., 1970), which was a more general study that included both polar regions and covered a somewhat shorter time scale. The Committee on Polar Research is supported by a contract from the Office of Polar Programs, National Science Foundation. James H. Zumberge, Chairman Committee on Polar Research
Preface This is the report of a study, convened by the Panel on Oceanography of the Committee on Polar Research, to draft a 10-year plan for scientific exploration of the physical oceanography of the Southern Ocean. To prepare the plan, the Panel established an ad hoc Study Group, which submitted an interim report to the Committee in January 1972. The task of the present ad hoc Working Group on Antarctic Oceanography was to enlarge on that report and to consider the interaction of such a program with evolving international plans for monitoring the global atmospheric-oceanic circulation during the next 10 years. This study was conducted during the summer and fall of 1972 at and between two meetings of the Working Group in Boulder, Colorado, and Wash- ington, D.C.; a number of other scientists also participated in the two meet- ings. An early draft of the report was circulated widely to interested scientists for further comment. This report has undergone critical review by a number of interested groups within the National Academy of Sciences and the National Research Council: the Committee on Science and Public Policy, the U.S. National Committee for the CARP, and the Ocean Science Committee of the Ocean Affairs Board. The comments and help of the latter group are especially appreciated. The Working Group noted that the present rapid development of new technology is pointing the way toward the solution of global environmental prediction problems. Long-term prediction of climate variability is one such problem requiring the proper monitoring of large-scale physical processes in the polar oceans. This report attempts to show some of the possible first steps toward the establishment of such monitoring in the Southern Ocean. The Working Group believes that continual planning should be a part of the overall effort to ensure the efficient utilization of available manpower and scientific resources. The recommended program has been organized to consist of a series of well-defined and sharply focused experiments that will permit careful review and efficient management of individual projects. The Working Group believes that its assessment of available resources indicates vii
viii Preface that the basic experimental sequence is both realistic and feasible. Only rough estimates of costs of such a program are possible. Since the costs will depend strongly on the details of individual experiments, ship and related logistics costs, and the concurrent development of other environmental monitoring programs, cost projections are best left to that group actually carrying out the program. In the Working Group's view, the financial support of a program of Southern Ocean physical oceanography is essential now if the United States is to take a substantive long-term role in global environmental prediction. The Panel is grateful to all those who participated in the preparation of this report and especially to Louis DeGoes, Executive Secretary of the CPR, and Victor T. Neal, Office of Polar Programs, National Science Founda- tion, for their contributions to the report's organization and publication. D. James Baker, Jr., Chairman Panel on Oceanography
Contents 1. SUMMARY OF PRINCIPAL RECOMMENDATIONS 1 I. General 1 II. Specific 2 2. GENERAL OBJECTIVES AND PROGRAM SUMMARY 3 I. Introduction 3 II. Specific Scientific Goals 4 A. Ocean Dynamics 4 B. Air-Sea Interaction 5 C. Sea-Ice-Air Interaction 5 D. Atmospheric Dynamics 6 HI. Ultimate Practical Goals 6 IV. Historical Background 7 V. Program Summary 10 3. DYNAMICS OF THE CIRCUMPOLAR CURRENT 12 I. Principal Recommendations 12 II. Introduction 13 III. Brief History 13 IV. Recommended Program 17 A. Elements of a Long-Term Monitoring Program 18 B. A Specific Experiment 21 C. The Polar Front and the Antarctic Circumpolar Current 21 D. Development of New Technology 22 E. Realistic Theoretical Models 23 F. Summary of Recommended Program 23 References 24 4. ANTARCTIC BOTTOM WATER FORMATION 25 I. Principal Recommendations 25 II. Introduction 26 III. Brief History 26 IV. Recommended Program 28 A. General Survey Data Required 28 ix
x Contents B. Data Required for Test of Hypotheses 28 C. Specific Program for the Weddell Sea 29 D. Development of New Technology 34 E. Theoretical and Laboratory Work 34 F. Summary of Recommended Program 34 References 36 5. EXCHANGE PROCESSES AND OVERALL BUDGETS 37 I. Principal Recommendations 37 II. Introduction 38 III. Brief Overview 39 A. Meridional Circulation and Air-Sea Interaction 39 B. Approximate Budgets 40 IV. Recommended Program 42 A. General Survey Data 43 B. Long-Term Monitoring 47 C. Technology for Long-Term Monitoring 48 D. Summary of Recommended Program 48 References 50 APPENDIX A Abbreviations Used in this Report 52
