Examples of Lyttelton Harbour Waves
Examples of Lyttelton Harbour Waves
Several examples are shown below of combinations of harbour waves under various conditions.
28-Feb was a lovely fine day and atmospheric pressure was high (1015 hPa). As a result, the smoothed residual (red curve) was slightly depressed under the tsunami.
The tsunami excited the Pegasus Bay seiche, resulting in three or four large oscillations, but the seiche quickly died away.
Harbour seiche was also excited and continued into the next day.
Long waves built up over several hours, then slowly died away.
On 8-Mar-2010, there was large southeasterly swell in Pegasus Bay, with wave heights reaching over 2 m. The waves had propagated up from storms in the Southern Ocean and were accompanied by FIG and IG waves. In fact, the IG waves caused such extreme surging of vessels at Cashin Quay that loading and unloading was suspended and the vessels were put to sea.
The lower plot shows the FIG waves.
At present, IG waves are not measured, so their presence must be inferred from the FIG waves.
After a few days of strong E to NE winds, harbour seiche was set up as shown to the left.
The habour seiche is not large compared to Pegasus Bay seiche or long waves