Fast Fourier Transform – Velocities and Temp. (1 hour period)
Velocity spectrum Cell 3
Velocity spectrum Outer Harbour
Velocity spectrum EGap (data W. Snodgrass)
Temperature spectrum Toronto Island.
The spectral analysis of the velocity time series show similar peaks for all the ADCP locations and bins.
Even the temperature spectral analysis in a Toronto Islands channel shows a strong peak for a period of T=1 hour (bottom right)
It is interesting to observe the data from the City of Toronto Water Infrastructure Management department (bottom left):
● They had a sampling period of half hour, which due to Nyquist theorem limits the accuracy of the spectral analysis to one hour period.
● However, we can still see the huge spike in the FFT plot close to the 1 hour period.
The magnitude of the peak for the spectal analysis of the Inner Harbour data suggests that Inner Harbour's natural oscillation frequency (eigen frequency) may have a period T = 1 h and its enhanced resonant oscillation may be the main driver of water exchange of the other embayments in Toronto Harbour.