Notes on Marsden Point Wave Forecasts 

The time series of wave height, period and direction come from the NOAA WaveWatch 3 (NWW3) model. There is information about the model here. The data were extracted for the node nearest Marsden Point at 175 deg E 36 deg S (about 48 km ESE of Marsden Point), as shown in the map to the right.

The confidence levels in significant wave heights were derived from an analysis of the waves that occurred from 1-Mar-1997 to 30-Jun-2005. The statistics of the period and direction of these waves are presented in the tables below. The tables show that the largest waves have periods between 8 and 12 seconds (i.e., they are swell waves), and the preferred direction is ENE.

Distribution (%) of the period of waves over various heights.
Period Top 50%
Hs > 1.2 m
Top 95%
Hs > 2.8 m
Top 99%
Hs > 4.1 m
Top 99.9%
Hs > 5.3 m
3 1.3% 0 0 0
5 27.3% 0.1% 0 0
7 24.3% 21.0% 0.8% 0
9 33.0% 53.9% 65.0% 37.5%
11 12.0% 21.4% 29.2% 62.5%
13 2.0% 3.6% 5.0% 0
15 0.1% 0 0 0

Distribution (%) of the direction of waves over various heights.
Direction Top 50%
Hs > 1.2 m
Top 95%
Hs > 2.8 m
Top 99%
Hs > 4.1 m
Top 99.9%
Hs > 5.3 m
N 7.1% 4.6% 2.5% 8.3%
NNE 9.6% 16.0% 11.3% 0
NE 11.1% 16.0% 14.6% 12.5%
ENE 27.0% 35.4% 39.2% 70.8%
E 20.7% 24.8% 31.7% 8.3%
ESE 4.5% 3.1% 0.8% 0
SE 0.8% 0 0 0
SSE 0.2% 0 0 0
S 0.6% 0 0 0
SSW 1.9% 0 0 0
SW 3.1% 0 0 0
WSW 3.7% 0 0 0
W 3.1% 0.1% 0 0
WNW 1.8% 0.1% 0 0
NW 1.4% 0 0 0
NNW 3.5% 0 0 0