Oceanology of the. Antarctic Continental Shelf

Transcription

1 Oceanology of the Antarctic Continental Shelf

2 ANTARCTIC American Geophysical Union RESEARCH SERIES Physical Sciences ANTARCTIC OCEANOLOGY Joseph L. Reid, Editor ANTARCTIC OCEANOLOGY I I: THE AUSTRALIAN- NEW ZEALAND SECTOR Dennis E. Hayes, Editor ANTARCTIC SNOW AND ICE STUDIES Malcolm Melior, Editor ANTARCTIC SNOW AND ICE STUDIES II A. P. Crary, Editor ANTARCTIC SOILS AND SOIL FORMING PROCESSES J. C. F. Tedrow, Editor DRY VALLEY DRILLING PROJECT L. D. McGinnis, Editor GEOLOGY AND PALEONTOLOGY OF THE ANTARCTIC Jarvis B. Hadley, Editor GEOLOGY OF THE CENTRAL TRANSANTARCTIC MOUNTAINS Mort D. Turner and John F. Splettstoesser, Editors GEOMAGNETISM AND AERONOMY A. H. Waynick, Editor METEOROLOGICAL STUDIES AT PLATEAU STATION, ANTARCTICA Joost A. Businger, Editor OCEANOLOGY OF THE ANTARCTIC CONTINENTAL SHELF Stanley S. Jacobs, Editor STUDIES IN ANTARCTIC METEOROLOGY Morton J. Rubin, Editor UPPER ATMOSPHERE RESEARCH IN ANTARCTICA L. J. Lanzerotti and C. G. Park, Editors THE ROSS ICE SHELF: GLACIOLOGY AND GEOPHYSICS C. R. Bentley and D. E. Hayes, Editors Biological and Life Sciences BIOLOGY OF THE ANTARCTIC SEAS Milton O. Lee, Editor BIOLOGY OF THE ANTARCTIC SEAS II George A. Llano, Editor BIOLOGY OF THE ANTARCTIC SEAS III George A. Llano and Waldo L. Schmitt, Editors BIOLOGY OF THE ANTARCTIC SEAS IV George A. Llano and I. Eugene Wallen, Editors BIOLOGY OF THE ANTARCTIC SEAS V BIOLOGY OF THE ANTARCTIC SEAS VI BIOLOGY or THE ANTARCTIC SEAS VII BIOLOGY OF THE ANTARCTIC SEAS VIII David L. Pawson and s BIOLOGY OF THE ANTARCTIC SEAS IX BIOLOGY OF THE ANTARCTIC SEAS X BIOLOGY OF THE ANTARCTIC SEAS XI BIOLOGY OF THE ANTARCTIC SEAS XII BIOLOGY OF THE ANTARCTIC SEAS XIII BIOLOGY OF THE ANTARCTIC SEAS XIV BIOLOGY OF THE ANTARCTIC SEAS XV BIOLOGY OF THE ANTARCTIC SEAS XVI ANTARCTIC TERRESTRIAL BIOLOGY George A. Llano, Editor TERRESTRIAL BIOLOGY I I Bruce Parker, Editor TERRESTRIAL BIOLOGY III Bruce Parker, Editor ANTARCTIC ASCID!ACEA Patricia Kott ANTARCTIC BIRD STUDIES Oliver L. Austin, Jr., Editor ANTARCTIC PINNIPEDIA William Henry Burr, Editor ANTARCTIC CIRRIPEDIA William A. Newman and Arnold Ross BIRDS OF THE ANTARCTIC AND SUB-ANTARCTIC George E. Watson ENTOMOLOGY OF ANTARCTICA J. Linsley Gressitt, Editor HUMAN ADAPTABILITY TO ANTARCTIC CONDITIONS E. K. Eric Gunderson, Editor POLYCHAETA ERRANTIA OF ANTARCTICA Olga Hartman POLYCHAETA MYZOSTOMIDAE AND SEDENTARIA OF ANTARCTICA Olga Hartman RECENT ANTARCTIC AND SUBANTARCTIC BRACHIOPODS Merrill W. Foster

3 ANTARCTIC Vol t e 43 RESEARCH SERIES Oceanology of the Antarctic Continental Shelf Stanley S. Jacobs, Editor American Geophysical Union Washington, D.C. 1985

4 ANTARCTIC Volume 43 RESEARCH SERIES OCEANOLOGY OF THE ANTARCTIC CONTINENTAL SHELF STANLEY S. JACOBS, Editor Published under the aegis of the Board of Associate Editors, Antarctic Research Series Charles R. Bentley, Chairman Samuel C. Colbeck, Robert H. Eather, David Elliot, Dennis Hayes, Louis S. Kornicker, Heinz Lettau, and Bruce Parker Library of Congress Cataloging in Publication Data Main entry under title: Oceanology of the Antarctic continental shelf. (Antarctic research series, ISSN ; v. 43) 1. Continental shelf--antarctic regions. I. Jacobs, Stanley S. II. Series. GC85.2.A ISBN I SSN Copyright 1985 by the American Geophysical Union 2000 Florida Avenue, N.W. Washington, D.C Figures, tables, and short excerpts may be reprinted in scientific books and journals if the source is properly cited. Authorization to photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by the American Geophysical Union for libraries and other users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service, provided that the base fee of $1.00 per copy, plus $0.10 per page is paid directly to CCC, 21 Congress St., Salem, MA /85/$ This consent does not extend to other kinds of copying, such as copying for creating new collective works or for resale. The reproduction of multiple copies and the use of full articles or the use of extracts, including figures and tables, for commercial purposes requires specific permission from AGU. Published by AMERICAN GEOPHYSICAL UNION With the aid of grant DPP from the National Science Foundation Printed in the United States of America

5 CONTENTS The Antarctic Research Series: Statement of Objectives Board of Associate Editors Preface vii ix GEBCO Bathymetric Sheet 5.18 (Circum-Antarctic) J. R. Vanney and G. L. Johnson Circulation and Water Masses on the Southern Weddell Sea Shelf A. Foldvik, T. GammelsrCd, and T. Terresen Bottom Currents Near the Continental Shelf Break in the Weddell Sea Arne Foldvik, Thor Kvinge, and Tot Terresen Interaction Between Ice Shelf and Ocean in George VI Sound, Antarctica. J. R. Potter and J. G. Paten Origin and Evolution of Water Masses Near the Antarctic Continental Margin: Evidence From H2180/H2160 Ratios in Seawater Stanley S. Jacobs, Richard G. Fairbanks, and Yoshio Horibe Preliminary 'Observations From Long-Term Current Meter Moorings Near the Ross Ice Shelf, Antarctica R. Dale Pillsbury and Stanley S. Jacobs Tidal Rectification Below the Ross Ice.Shelf, Antarctica D. R. MacAyeal Evolution of Tidally Triggered Meltwater Plumes Below Ice Shelves D. R. MacAyea! The Winter Oceanography of McMurdo Sound, Antarctica E. L. Lewis and R. G. Perkin Observations in the Boundary Layer Under the Sea Ice in McMurdo Sound W. M. Mitchell and J. A. T. Bye A Recurring, Atmospherically Forced Polynya in Terra Nova Bay Dennis D. Kurtz and David H. Bromwich Antarctic Offshore Leads and Po!ynyas and Oceanographic Effects H. Jay Zwaily, J. C. Comiso, and A. L. Gordon A Passive Microwave Study of Polynyas Along the Antarctic Wilkes Land Coast Donald J. Cavalieri and Seelye Martin Some Effects of Ocean Currents and Wave Motion on the Dynamics of Floating Glacier Tongues G. Holdsworth Tidal Measurements Along the Antarctic Coastline J. R. E. Lutjeharms, C. C. Stavropoulos, and K. P. Koltermann Oceanographic Influences on Sedimentation Along the Antarctic Continental Shelf Robert B. Dunbar, John B. Anderson, Eugene W. Domack, and Stanley S. Jacobs

6 THE ANTARCT ( RESEARCH ' :"": ' '"'... STATEMENT OF OBJE( TI ; E The Antarctic Research Series, an outgrowth of research d e ' '? t e Antarctic during the International Geophysical Year, was begun early in 1963 with a grant from the National Science Foundation to AGU. It is a book series designed to serve scientists and graduate students actively engaged in Antarctic or closely related research and others versed in the biological or physical sciences. It provides a continuing, authoritative medium for the presentation of extensive and detailed scientific research results from Antarctica, particularly the results of the United States Antarctic Research Program. Most Antarctic research results are, and will continue to be, published in the standard disciplinary journals. However, the difficulty and expense of conducting experiments in Antarctica make it prudent to publish as fully as possible the methods, data, and results of Antarctic research projects so that the scientific community has maximum opportunity to evaluate these projects and so that full information is permanently and readily available. Thus the coverage of the subjects is expected to be more extensive than is possible in the journal literature. The series is designed to complement Antarctic field work, much of which is in cooperative, interdisciplinary projects. The Antarctic Research Series encourages the collection of papers on specific geographic areas (such as the East Antarctic Plateau or the WedSell Sea). On the other hand, many volumes focus on particular disciplines, including marine biology, oceanology, meteorology, upper atmosphere physics, terrestrial biology, snow and ice, human adaptability, and geology. Priorities for publication are set by the Board of Associate Editors. Preference is given to research projects funded by U.S. agencies, long manuscripts, and manuscripts that are not readily publishable elsewhere in journals that reach a suitable reading audience. The series serves to emphasize the U.S. Antarctic Research Program, thus performing much the same function as the more formal expedition reports of most of the other countries with national Antarctic research programs. The standards of scientific excellence expected for the series are maintained by the review criteria established for the AGU publications program. The Board of Associate Editors works with the individual editors of each volume to assure that the objectives of the series are met, that the best possible papers are presented, and that publication is achieved in a timely manner. Each paper is critically reviewed by two or more expert referees. The format of the series, which breaks with the traditional hard-cover book design, provides for rapid publication as the results become available while still maintaining identification with specific topical volumes. Approved manuscripts are assigned to a volume according to the subject matter covered; the individual manuscript (or group of short manuscripts) is produced as a soft cover 'minibook' as soon as it is ready. Each minibook is numbered as part of a specific volume. When the last paper in a volume is released, the appropriate title pages, table of contents, and other prefatory matter are printed and sent to those who have standing orders to the series. The minibook series is more useful to researchers, and more satisfying to authors, than a volume that could be delayed for years waiting for all the papers to be assembled. The Board of Associate Editors can publish an entire volume at one time in hard cover when availability of all manuscripts within a short time can be guaranteed. BOARD OF ASSOCIATE EDITORS ANTARCTIC RESEARCH SERIES

7 PREFACE This is the first oceanology volume of the Antarctic Research Series to be devoted to the continental shelf. That region is of special interest because of its great depth and its climatic role in the production of sea ice, ventilation of the deep ocean, and wastage of the Antarctic ice sheet. Sea ice persists along much of the continental shelf during the austral summer, so that shipboard observations there have often been difficult and sometimes dangerous. Fortunately, time series measurements from bottom-moored instruments and analyses of satellite imagery are beginning to supplement the data that can be collected on summer expeditions. Geochemical tracers, high-resolution vertical profiling instruments and computer modeling are also providing new insights into the continental shelf circulation. Antarctic oceanology is both interdisciplinary and international, as attested by the authors' diverse interests and affiliations. Their contributions are not lack- ing in jargon peculiar to the various trades, nor in adopted terminology with subtly different meanings. For example, a geologist's meltwater is evidenced in shelf sediment patterns, and may have been generated by pressure melting or frictional heat where the ice sheet is grounded. An oceanographer's meltwater is identified by water column tracers and has mostly been derived from oceanic or atmospheric heat flux into the glacial ice or sea ice. Oceanology is also in a transitional stage between classical, discrete shipboard measurements and continuous remote sensing. That evolution is emphasized in this volume by literature reviews, early results from an ongoing experiment, and an updated description of some pioneering long-term current and temperature measurements. Several authors took advantage of the opportunity to exchange critical reviews and cross-reference their work to other papers in the volume. The separate reference lists may together serve as a useful bibliography for the continental shelf regime. The accompanying GEBCO circum-antarctic chart effectively portrays the continental shelf in relation to the glaciated continent and surrounding deep ocean. It also displays several ephemeral bathymetric features and extensive areas that are relatively unknown. Some of the hypotheses and interpretations in this volume may also prove to be short-lived, particularly where the data bases are incomplete. Better information about the thickness distribution and drift of sea ice, the calving and attrition rate of icebergs, and the details of processes at shelf water boundaries could improve the heat, salt, and other budgets. Perhaps the work reported here will suggest other leads to be followed and stimulate synergistic collabora tions. Many anonymous reviewers made valuable contributions to the papers in this volume. The GEBCO 5.18 sheet was made available with the assistance of the Canadian Hydrographic Service. Copyediting was carried out under the direction of the staff of the American Geophysical Union. Camera-ready word processing was done by D. Criscione at Lamont-Doherty Geological Observatory, in part with support from the Department of Energy. Many of the field projects and laboratory studies were supported by the U.S. Antarctic Research Program of the National Science Foundation. Stanley S. Jacobs