Tidal analysis and prediction

Ali Reza Payandeh
Louisiana State University, Oceanography and Coastal Sciences
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Summary

This activity explores theoretical concepts for student to better understand tides. Students calculate tidal constituent amplitudes and phases with the help of the T_TIDE Matlab software package using observed water levels and compare them to the NOAA published amplitudes and phases.

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Learning Goals

Concepts: Tidal forces (astronomic vs. meteorological tides), Basic statistics of sea levels as time series, Tidal harmonic analysis and prediction
Students use T-Tide MATLAB package for the analysis and prediction of tides. It allows students to decompose a water level timeseries into its tidal components (tidal harmonic constituents). The constituents are then used for future prediction of tides.

Context for Use

This activity is in graduate course taken mostly by students in Oceanography and coastal science. Students have already basics of MATLAB, but do not necessarily have other programing experience.

Description and Teaching Materials

In this three-part activity, students will first learn basic concepts about tides and harmonic analysis. Then they will visit NOAA Tides and Currents website, select two tide gages with distinct sea levels and reconstruct water levels based on the 4 highest tidal constituents and plot the results using MATLAB. After that students will calculate tidal constituent amplitudes and phases with the help of the T_TIDE Matlab software package using observed water levels and compare them to the NOAA published amplitudes and phases.




Teaching Notes and Tips

I have found that the main challenge for students is to successfully program their own script, or functions. Helping them to read an existing complex code for understanding can be rewarding.

Assessment

If the code that student develops runs cleanly (50%). If the code produces nice figures (30%) and if student's final report is well-written, the student receives a good grade.

References and Resources

https://tidesandcurrents.noaa.gov/


T_Tide Harmonic Analysis Toolbox

https://www.eoas.ubc.ca/~rich/#T_Tide