Can the tides at night be consistently higher than in the daytime in southwest Australia in the port of Fremantle? Also, what is the explanation for the tides being significant during a part of the year, and then disappear.
I find the statement in the question difficult to believe.Tides have a pretty cyclical period and I doubt the resulting effect is a day-night difference unless only S1 and S2 tidal constituents are important in that location, which I find very unlikely.
In fact, the portal https://www.tide-forecast.com/locations/Fremantle-Australia/tides/latest shows the high tide being larger during the day for the rest of the month of May 2018. That behavior changes in time as one would expect. The dominant frequencies at this location are diurnal tides (mostly a single high tide and low tide per day). The main diurnal tides have a period around 24 hours and in this case the dominant periods are slightly larger than 24 hours.
You can download the hourly data from: http://uhslc.soest.hawaii.edu/data/netcdf/fast/hourly/h175.nc and the resulting time series goes from 1984 to now. Here is the time series for the year 2017. There is no time at which the tide "dissappears". The resulting harmonic analysis (using t_tide) shows that the tidal constituents with amplitudes over about 5 cm are:
Constituent Period (h) Magnitude (m) O1 25.82 0.1206 K1 23.93 0.1667 M2 12.42 0.0525 S2 12.00 0.0465
The dominant constituents are K1 and O1, with comparable amplitudes. The resulting effect of the two main diurnal frequencies is a period slightly over 24 hours. The effect of the semidiurnal constituents (M2, S2) is smaller and can be seen in the first time series as slight humps in May 24-27.
- T_tide: Pawlowicz, R., B. Beardsley, and S. Lentz, "Classical Tidal "Harmonic Analysis Including Error Estimates in MATLAB using t_tide", Computers and Geosciences, 28, 929-937 (2002).