Manual on sea level measurement and ... - unesdoc - Unesco

Sea Level Measurement and InterpretationTable of contents1. Introduction .......................................................................................................... 12. The Nature of Sea Level Variations ..................................................................... 22.1 Introduction ...................................................................................................................................22.2 Surface Waves ................................................................................................................................32.3 Seiches ...........................................................................................................................................42.4 Tides ..............................................................................................................................................42.4.1 Tidal Analysis .................................................................................................................................52.5 Storm surges ..................................................................................................................................62.6 Tsunamis ........................................................................................................................................72.7 Mean Sea Level and Trends ............................................................................................................72.8 Estimation of Extreme Sea Levels ....................................................................................................72.8.1 Introduction ..................................................................................................................................72.8.2 The Annual Maximum Method (AMM) .........................................................................................82.8.3 The Joint Probabilities Method (JPM) .............................................................................................82.8.4 The Revised Joint Probabilities Method (RJPM) ..............................................................................92.8.5 The Exceedance Probabilities Method ...........................................................................................92.8.6 Spatial Estimation of Extremes ......................................................................................................93. Instruments for the Measurement of Sea Level .............................................. 103.1 Introduction .................................................................................................................................103.1.1 The Choice of a Tide Gauge Site ................................................................................................ 103.2 The Stilling Well ...........................................................................................................................123.2.1 Datum Switches ..........................................................................................................................123.3. Pressure Gauges ..........................................................................................................................133.3.1 Pneumatic Bubbler Gauges .........................................................................................................133.3.2 Pressure Sensor Gauges ..............................................................................................................143.3.3 The Datum of a Pressure System .................................................................................................153.3.4 Multiple Pressure Transducer Systems (‘B’ gauges) ......................................................................163.3.5 Pressure Transducers in Stilling Wells ...........................................................................................163.3.6 Bottom-mounted Pressure Gauges .............................................................................................163.4 Acoustic Tide Gauges ...................................................................................................................173.4.1 Acoustic Gauges with Sounding Tubes .......................................................................................173.4.2 Acoustic Gauges without Sounding Tubes ..................................................................................173.5 Radar Gauges ...............................................................................................................................193.6 Summary of the Merits of Different Technologies .........................................................................21iii