CONTENTS 



Page 



CONVERSION FACTORS, U.S. CUSTOMARY TO METRIC (SI) ... 9 



SYMBOLS AND DEFINITIONS 10 



I INTRODUCTION 13 



n DESCRIPTION OF THE RECORDS 15 



1. Astronomical Tides 15 



2. Water Level Records 18 



3. Tide Observations and Tide Record Analysis 21 



4. Perturbations in Tide Records with Periods Much Longer Than the 



Tidal Period 21 



im THE TIDE PREDICTION EQUATION 24 



1. The Tide Generation Force 26 



2. The DecUnation of the Sun and Moon 30 



3. Interaction of Solar and Lunar Tides 32 



4. Net Variation in Tidal Range 32 



5. Shallow-Water Tides 33 



6. Classical Harmonic Constituents of the Tide 34 



7. Tide Analyses 35 



IV TIDAL DATUMS 36 



1. The National Geodetic Vertical Datum (NGVD) 38 



2. Tidal Datum Bench Marks 40 



V SPECIAL DATUMS FOR THE GREAT LAKES 46 



1. Early Great Lakes Datums 46 



2. The Definition of Elevation 50 



3. The International Great Lakes Datum (1955) 52 



VI LONG-TERM VARLVTION IN MEAN SEA LEVEL 53 



1. Explanation of Sea Level Trends 58 



2. Conclusions and Recommendations 59 



3. Data Sources for Detailed Studies 59 



VH STATISTICAL DESCRIPTION OF THE PREDICTED TIDE 61 



1. Introduction 61 



2. Tide Hydrographs 61 



3. Graphs Displaying Other Tide Characteristics 62 



4. Tide ProbabiHty Graphs 66 



5. ProbabUity Tables for Astronomical Tides 70 



