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The Structure of Water Mass, Salt, and Temperature Transports Within Intermediate Depths of the Western Tropical Atlantic Ocean

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The Structure of Water Mass, Salt, and Temperature Transports Within Intermediate Depths of the Western Tropical Atlantic Ocean University of New Hampshire University of New Hampshire Scholars' Repository Doctoral Dissertations Student Scholarship Winter 1993 The structure of water mass, salt, and temperature transports within intermediate depths of the western tropical Atlantic Ocean Frank Lee Bub University of New Hampshire, Durham Follow this and additional works at: https://scholars.unh.edu/dissertation Recommended Citation Bub, Frank Lee, "The structure of water mass, salt, and temperature transports within intermediate depths of the western tropical Atlantic Ocean" (1993). Doctoral Dissertations. 1762. https://scholars.unh.edu/dissertation/1762 This Dissertation is brought to you for free and open access by the Student Scholarship at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. University Microfilms International A Bell & Howell Information C om pany 300 North Z eeb Road. Ann Arbor. Ml 48106-1346 USA 313/761-4700 800/521-0600 Order Number 9420570 The structure of water mass, salt, and temperature transports within intermediate depths of the western tropical Atlantic Ocean Bub, Frank Lee, Ph.D. University of New Hampshire, 1993 UMI 300 N. ZeebRd. Ann Arbor. MI 48106 THE STRUCTURE OF WATER MASS, SALT, AND TEMPERATURE TRANSPORTS WrrUIN INTERMEDIATE DEPTHS OF THE WESTERN TROPICAL ATLANTIC (X;iAN BY FRANK LEE BUB B. S., Lehigh University, 1968 M. S., Naval Postgraduate School, 1974 DISSERTATION Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Earth Sciences: Oceanography December, 1993 This dissertation has been examined and approved. Ia J ij ^ ju l L 5. Dissertation Di rector,1 Dr. Wendell S. Brown Professor of Earth Sciences and Earth, Oceans and Space University of New Hampshire Dr*. James A. Carton /yssociate Professor of Meteorology University of Maryland C . arU -uA A f)r. Robert C. Harriss Professor of Earth Sciences and Earth, Oceans and Space University of New Hampshire Dr. Professor of Physical Oceanography Rosenstiel School of Marine and Atmospheric Science University of Miami TL Dr. Robert L Nlolinari Director, Physical Oceanography Atlamic Oceanographic and Meteorological Laboratory, Miami II Dr. Berrien Moore, III Associate Professor of Mathematics and Professor of Earth, Oceans and Space University of New Hampshire Date DKDfCA'IliDTD Susan Rines Bub wife, partner, and friend, whose love and understanding kept me going and helped me finish, AND Kristen Lee Bub Our daughter, who said we could do it, AND Robert A. and Ruth R. Bub My parents, who taught me the value of hard work and perseverance. ACKNOWLEDGEMENTS My heartfelt appreciation is extended to Dr. Wendell Brown, who was my able and enthusiastic advisor in this research. I am indebted to the other members of my committee whose sage advice and timely assistance made this a better piece of work. In particular, I appreciate the attention and interest of Dr. Robert Molinari. The friendship and intellectual discussions by Ilson Da Silveira helped me clarify my thoughts and explain myself better. The assistance of Karen Garrison and Russ Gelinas are appreciated. The many efforts by Mariellen Lee to find the money and keep us going, despite some hard times, are much appreciated. The dedication and hard work of the crews of the NOAA Ships Mount Mitchell and Malcolm Baldrige are to be commended. The CTD observations by AOML, and Pegasus velocity observations by University of Miami scientists were essential. The combined efforts by these various groups produced the beautiful data sets upon which this research is based. Many of the graphics in this dissertation were prepared in the University of New Hampshire Visualization Laboratory which was donated for the University's use by the Digital Equipment Company. I am deeply indebted to the National Oceanographic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF), whose funding supported this work. TABLE OF CON'Il-NTS DIDICA'DON __ _ _____ iii ACKNOWl.EDGEMEN'I'S______________________________________________ iv TABUiOl CONTEN'IS_____________________________________________ v IJST Ol TABLES__________________________________________________________Vii LIST Ol FIGURES_________________________________________________ viii ABSTRACI’____________________________________________________________ xii I. INTRODUCHON A. Goals and objectives 1 B. Context ___________________________________________________________ 2 C. I be WESTRAX region _________________________ 2 I). Historical background _____________________________________________6 I-. Oissertation fra m e w o rk ____________________________________11 II. MEASUREMENTS AND DATA REDUCTION A. WESTRAX expeditions ___________________________________ 14 B. CTD hydrographic measurements __________________________________16 C. Pegasus velocity measurements___ ________________________________ 22 D. A comparison between Pegasus and ADCP observations _____________ 27 III. DATA ANALYSES - INTERPOLATION AND STREAM FUNCTION A. Interpolation of data to a grid _____________________________________ 32 B. Divergent versus non-divergent transports ________________________37 C. Stream function analysis _________________________________________ 37 iv. vELocrnr structure A. O verview ____________________________________________________ 42 B. WESTRAX region transport structure ______________________________ 49 C. Transport associated with retroflection eddies ______________________55 V. WATER MASSES A. Definitions and backgrounds .61 page \ i B. Tropical Atlantic water masses ........... 62 C. WESTRAX region water masses ................................................................. 70 VI. WATER MASS TRANSPORT STRUCTURE A. Northern and southern water mass origins .................. ...............80 B. Water mass transport pathways ..................... 01 I). Transport associated with retroflection eddies .................... 01 E. Estimated mixing transports............................. _... 102 VII. DISCUSSION A. Oceanic current summary ............ 1<X> B. Eddy-scale transport summary ........................................................................100 C. Mixing transport summary ___________________ ______ 100 D. Some comparisons with other studies ......................................................... 110 E. A speculative model of the annual evolution of structure ....................112 F. Unresolved issues ................................. 115 VIII. CONCLUSIONS______________________________________________________ 117 APPENDICES A. INTERPOLATION ALGORITHM............................. .......................... .......... ...... 110 B. ITIE STREAM FUNCTION EQUA IION............... 122 C. TWO-DIMENSIONAL FINITE DIFFERENCE ANALYSIS______________ 126 D. THE COMPUTATION OF VERTICAL VELOCITY .................................. 132 E. A COMPARISON OF DATA ANALYSIS TECHNIQUES____________________ 136 F. VELOCITY STRUCTURE_______________________________________ 1-16 G. HYDROGRAPHIC STRUCTURE______________________________________ 170 H. THE ANALYSIS OF WATER MASS FORMATION, MOVEMENT, AND MIXING USING A TEMPERATURE-SALINITY DIAGRAM____________ 200 I. WATER MASS STRUCTURE .... 205 J. VOLUME, SALT, TEMPERATURE AND FRESHWATER TOANSPORT CALCULATIONS____________________________________ 217 IJST OF REFERENCES. .220 IJST OH TABLES 1. Summary of WHSTRAX observations ___________ _______________________ 14 2. CTO salinity corrections and precision estimates _____________ 18 S. Typical depth-averaged Pegasus velocities and systematic velocity errors in the upper 1500 m ___________ ....__ 27 4. Comparison of Pegasus and ADCP zonal transports across simultaneously observed portions of section B (44 W) ______________ 50 5. Intermediate layer divergent and non-divergent transports through the WESTRAX region _______________________________________ 86 6. Tropical Atlantic Ocean water types__ __________________________________66 7. WESTRAX region water mass classifications
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