This lab will use the T_Tide Harmonic Analysis Toolbox for Matlab developed by Rich Pawlowicz at UBC. The program takes a raw tidal time series as input and outputs the amplitude and phase of the harmonic constituents for the time series, along with error estimates.

The objectives for this lab are as follows.

1. Input a tidal time series into the T_Tide function.

• Read the T_Tide reference listed below (Pawlowicz et al., 2002)
• See the lab presentation for how to run t_tide
• The example script "t_demo" included with the t_tide package shows an example of the capabilities of t_tide.

2. Compare the derived harmonics (t_tide) to the published harmonics for the source data. (Make sure that you are using the correct time zone)

• Comment on differences in the harmonic constituents. (Ex. Which constituents are missing between the two lists and why? How different are the amplitudes and phases? and any other observations you can think of)
• Are the differences in Amplitude and Phase between the predicted (t_tide) and published constituents within the predicted confidence inteval (from t_tide) for that constituent (M2,K1,...) ?

3. Characterize what type of tide you are dealing with (see Form Number in notes)

4. Are Rotation Effects important in the entrance to the Bay of Fundy? (ie. Calculate is the Rossby Radius for the highlighted area in the image below)
   

5. Plot the original tidal time series and the new predicted times series output from T_Tide.

• Determine the residuals between the predicted tides and the original tidal series (make sure they are in the same time zone) 

6. Examine the residual tidal time series and explain the residuals based on meteorological data from the same time period. (Ex. Pressure, Wind, River Discharge, Precipitation, etc.) 

7. Present your tidal residuals in class (very short presentation) along with an explanation of why they exist (from Question 4) on November 26th, 2007.

Once the residuals have been determined for each location, they will be submitted to the TA. The residuals will then be compared to see if there are any patterns between the stations. This will be done in class on November **th, 2007, therefore the tidal time series residuals must be submitted before then. To compare the tidal residuals it is important to keep track of whether you are working in local time or UTC

Analysis will be performed on the following stations for the time period of June 22nd, 2006, at 14:30:00 UTC to Aug 1st, 2006, at 0:00:00 UTC.

Station	Tides	Published Harmonic Constituents	Meteorological Data
Saint John, NB	Available from DFO	Available from Bluefile**	Available from Environment Canada
North Head, Grand Manan, NB	Available*	Available from Bluefile**	Available from Environment Canada
Digby, NS	Available*	Available from Bluefile**	Available from Environment Canada
Lighthouse Cove, Brier Island, NS	Available*	Available from Bluefile**	Available from Environment Canada
Yarmouth, NS	Available from DFO	Available from Bluefile**	Available from Environment Canada
Eastport, ME	Available from NOAA	Available from NOAA	Available from NOAA
Cutler Naval Base, ME	Available from NOAA	Available from NOAA	Available from NOAA

*Corrected tide data obtained from DFO (Nov. 17th, 2006). Time in UTC.
**Third column of Bluefile is amplitude in millimeters and forth column is phase in decidegrees. The timezone used in the Bluefile is the fifth column.

Resources:

• R. Pawlowicz, B. Beardsley, and S. Lentz, "Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE", Computers and Geosciences 28 (2002), 929-937.




• Foreman, M.G.G., 1977. Manual for Tidal Heights Analysis and Prediction. Pacific Marine Science Report 77-10, Institute of Ocean Sciences, Patricia Bay, Sidney, B.C., 58 pp. (2004 revision).

   

Last Updated November 2nd, 2007