FALL 2000, ESEP-21 Seminar series:

Janurary 18, 4:00 to 5:00 pm, room 1500 EECS (north campus)

A Long-Term Wave Hindcast for the New Zealand Coast

RICHARD GORMAN, Scientist-Modeller
New Zealand National Institute of Water & Atmospheric Research

Abstract

The WAM wave generation model has been established over a domain covering the Southwest Pacific and Southern Oceans. The model has been used to hindcast the generation and propagation of deep-water waves incident on the New Zealand coast over a 15-year period (1979-93), forced using winds taken from the European Centre for Medium Range Weather Forecasting (ECMWF) analysis dataset. The hindcasts were compared with data from several in-situ wave records, and found to provide a satisfactory simulation of wave conditions at sites on exposed coasts. With the application of site-specific wave transformations to correct for refraction and limited fetch, good agreement is also obtained in regions of more complex coastal topography. This hindcast is intended to help fill the gaps in New Zealand's historic wave data coverage, which has been very limited, particularly for directional records. The resulting artificial climatology is expected to provide a valuable tool for researchers and coastal planners. For example, the hindcast allows an estimate of the long-term distribution of longshore and cross-shore wave energy fluxes along the entire coastline. The predominance of swell from the Southern Ocean results in a predominantly northward energy flux, with magnitude decreasing from south to north. This pattern is modified by large-scale coastal features such as the Taranaki Peninsula, on the south coast of which a southward flux is produced, consistent with sediment transport evidence.


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