Water levels and Velocities correlation ( Embayment C data)

Bin 2: Simple correlation :

Wavelet Coherence Transform

• Between dz/dt and velocity (bin2)
• Shows strong correlation at a period T = 1 [hour]
• Suggests seiches have a dominant role in driving the water exchange

Notes:

●A metric that shows how strong the correlation is between water level oscillations and velocities is the Pearson correlation (R2). For Embayment C and bin 2 the correlation is quite strong as seen ih the left figure above.

●However, simple correlation is inappropriate for non-stationary processes as it averages in time.

●We applied the wavelet coherence transform (WCT) that can be used to gain confidence in causal relationships and test mechanistic models of physical relationships between the time series in time-frequency space, even when the common power is low.

●The confidence levels are calculated against red noise backgrounds using Monte Carlo simulations.

●WCT correlation shows that there is a strong relationship between the water level oscillations and currents in the harbour. WCT identifies that the 1 hour oscillation is the most influential, which confirms our visual observation from the previous slides.

●What causes this 1 hour oscillation?