Tidal Datums, Marine Grids, and Sea Surface Topography
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NOAA Technical Memorandum NOS CS 27 VDATUM FOR THE COASTAL WATERS FROM THE FLORIDA SHELF TO THE SOUTH ATLANTIC BIGHT: TIDAL DATUMS, MARINE GRIDS, AND SEA SURFACE TOPOGRAPHY Silver Spring, Maryland May 2012 noaa National Oceanic and Atmospheric Administration U.S. DEPARTMENT OF COMMERCE National Ocean Service Coast Survey Development Laboratory Office of Coast Survey National Ocean Service National Oceanic and Atmospheric Administration U.S. Department of Commerce The Office of Coast Survey (OCS) is the Nation’s only official chartmaker. As the oldest United States scientific organization, dating from 1807, this office has a long history. Today it promotes safe navigation by managing the National Oceanic and Atmospheric Administration’s (NOAA) nautical chart and oceanographic data collection and information programs. There are four components of OCS: The Coast Survey Development Laboratory develops new and efficient techniques to accomplish Coast Survey missions and to produce new and improved products and services for the maritime community and other coastal users. The Marine Chart Division acquires marine navigational data to construct and maintain nautical charts, Coast Pilots, and related marine products for the United States. The Hydrographic Surveys Division directs programs for ship and shore-based hydrographic survey units and conducts general hydrographic survey operations. The Navigational Services Division is the focal point for Coast Survey customer service activities, concentrating predominately on charting issues, fast-response hydrographic surveys, and Coast Pilot updates. NOAA Technical Memorandum NOS CS 27 VDATUM FOR COASTAL WATERS FROM THE FLORIDA SHELF TO THE SOUTH ATLANTIC BIGHT: TIDAL DATUMS, MARINE GRIDS, AND SEA SURFACE TOPOGRAPHY Zizang Yang and Edward P. Myers Office of Coast Survey, Coast Survey Development Laboratory, Silver Spring, MD Inseong Jeong and Stephen A. White National Geodetic Survey, Silver Spring, MD May 2012 noaa National Oceanic and Atmospheric Administration U. S. DEPARTMENT National Oceanic and National Ocean Service OF COMMERCE Atmospheric Administration David Kennedy, John Bryson, Dr. Jane Lubchenco, Assistant Administrator Secretary Under Secretary Office of Coast Survey Coast Survey Development Laboratory Captain John Lowell, NOAA Mary Erickson NOTICE Mention of a commercial company or product does not constitute an endorsement by NOAA. Use for publicity or advertising purposes of information from this publication concerning proprietary products or the tests of such products is not authorized. ii TABLE OF CONTENTS LIST OF FIGURES ........................................................................................................... iv LIST OF TABLES ............................................................................................................. vi ABSTRACT ...................................................................................................................... vii 1. INTRODUCTION ...........................................................................................................1 2. COASTLINE, BATHYMETRY, AND TIDAL DATUM OBSERVATIONS ...............3 2.1. Digital Coastline ...............................................................................................3 2.2. Bathymetric Data ..............................................................................................3 2.3. Tidal Datum Data ..............................................................................................7 3. TIDAL DATUM SIMILATION ......................................................................................9 3.1. Hydrodynamic Model .......................................................................................9 3.2. Model Grid ........................................................................................................9 3.3. Bathymetry of Model Grid ..............................................................................14 3.4. Model Parameter Setup ...................................................................................17 3.5. Tidal Datum Computation and Results ...........................................................18 3.6. Verifications and Error Corrections ................................................................21 4. CREATION AND POPULATION OF THE MARINE GRID .....................................39 4.1. Creation of VDatum Marine Grid ...................................................................39 4.2. Population of VDatum Grid with Tidal Datums .............................................40 5. TOPOGRAPHY OF THE SEA SURFACE ..................................................................43 5.1. Generation of TSS Field .................................................................................43 5.2. Validation ........................................................................................................43 6. SUMMARY ...................................................................................................................47 ACKNOWLEDGMENTS .................................................................................................47 REFERENCES ..................................................................................................................47 APPENDIX A. HORIZONTAL AND VERTICAL ACCURACY STANDARDS FOR NOAA BATHYMETRY SURVEY ...............................................................51 APPENDIX B. WATER LEVEL STATION DATA ........................................................52 APPENDIX C. TIDAL DATUM FIELDS DEFINED ON VDATUM MARINE GRID .......................................................................................................................71 APPENDIX D. CREATION AND VALIDATION OF MODELED TSS FIELD ...........89 iii LIST OF FIGURES Figure 1. Map of the coastal areas of the FL shelf and the SAB. Black lines illustrate the MHW shoreline. The green line denotes a distance 25-nautical miles offshore. In the figure, the site abbreviations are CSB: Cape San Blas, BB: the Big Bend, PK: Pavillion Key, and OB: Onslow Bay... ...................................2 Figure 2. Locations of NOS sounding data (points in blue) .................................................4 Figure 3. Locations of ENC bathymetric data (points in blue) ............................................5 Figure 4. model grid where bathymetric data (points in blue) had been interpolated ..........6 Figure 5. Finite element grid for the entire model domain. The two red lines denote the model’s two open ocean boundaries.. ...........................................................10 Figure 6. Close-up views of the model grid for (a) the Tampa Bay and Charlotte Harbor, (b) the Pavilion Key, Florida Bay, and Key West, and (c) the northern SAB coast.. ...........................................................................................11 Figure 7 (a) Model grid bathymetry in [0, 300] m. The bathymetry beyond 300 m is shown in the same color as that of the 300-m. (b) Model grid bathymetry in [300, 6000] m. The bathymetry less than 300 m is shown in the same color as that of the 300-m bathymetry .................................................15 Figure 8. Spatially-varied bottom friction coefficient (Cf) .................................................17 Figure 9. Model-derived tidal datum fields, (a) MHHW, (b) MHW, (c) MLW, and (d) MLLW. Color bars are in meters. ................................................................19 Figure 10. Comparisons of the modeled and observed datums for (a) MHHW, (b) MHW, (c) MLW, and (d) MLLW. ................................................................21 Figure 11. Color-scaled absolute average of model-data errors (|md|avg) for (a) the west FL shelf, (b) the middle west FL, (c) the south FL shelf and Key West, (d) the east FL shelf, (e) the SAB area, and (f) the coastal South Carolina area. Red lines delineate a region in which model-data discrepancy is abnormally large compared with the other regions. Color bar is in cm. .........................................................................................................28 Figure 12. An illustration of overlapping areas between the present model domain and previously developed VDatum regions. Transects AA’ and BB’ mark locations at which the present and previous tidal datum results are compared. The green line delineates locations 25-nm offshore. The blue, red, and the cyan lines denote, respectively, the bounding polygons for the St. Joe’s Bay, AL, Gulf of Mexico, and Coastal Central North Carolina VDatum areas......................................................................................................29 Figure 13. Comparisons of tidal datums (a) MHHW, (b) MHW, (c) MLW, and (d) MLLW along transect AA’ (black circles in Figure 12). The abscissa, Location Index, is from A to A’. Blue squares are from the Gulf of Mexico and St. Joseph Bay results and red circles are from the present results. .............30 iv LIST OF FIGURES (Cont.) Figure 14. Comparisons of tidal datums (a) MHHW, (b) MHW, (c) MLW, and (d) MLLW along transect BB’ (red circles in Figure 12). The abscissa, Location Index, is from B to B’. Blue squares are from the Coastal Central North Carolina results and red circles are the present results. ............................31 Figure 15. TCARI interpolated error fields for (a) MHHW, (b) MHW, (c) MLW, and (d) MLLW, respectively. To enhance patterns of the error fields, each field is displayed with a color bar range of [-10, 10] cm; values