This lesson addresses how sea level is determined and applied. It starts with a general discussion of the surfaces that form the basis of measurement, called datums, then looks more closely at the vertical datums that form the basis of height measurements. We cover tidal datums in more depth, including the different datums, their extent, period of record (called a tidal epoch), and common applications. We conclude with a look at some data resources for tidal datums and sea level trends.
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After completing this lesson, the learner should be able to do the following:
- List the three types of vertical datums
- Describe the reference surface for each vertical datum
- Define the following terms:
- Sea surface height
- Ocean surface topography
- Global mean sea level
- Local mean sea level
- Relative sea level
- Recall the lateral extent of the different vertical datums
- Recall the geopotential datums in use (in 2016)
- Given a time series of water elevations at a tide gauge, identify the tide type
- List the different tidal datums and provide an example of a common application of each one
- Define tidal epoch and recall the national tidal datum epoch in 2016
- Describe the conditions under which a tidal datum is updated more frequently
- Describe the tidal datum information available
sea level, mean sea level, MSL, datum, vertical datum, tides, tidal datum, tidal epoch, local mean sea level, relative sea level, Mean lower low water, MLLW, mean high water, MHW, geoid, ellipsoid, orthometric, sea surface height, global mean sea level, ocean surface topography, dynamic ocean topography, NAVD 88, NGVD 29, National Tidal Datum Epoch, NTDE
