Tidal observations on the West Coast, South Island, New Zealand
作者:
R. A. Heath,
期刊:
New Zealand Journal of Marine and Freshwater Research
(Taylor Available online 1984)
卷期:
Volume 18,
issue 2
页码: 251-261
ISSN:0028-8330
年代: 1984
DOI:10.1080/00288330.1984.9516046
出版商: Taylor & Francis Group
关键词: tidal elevations;tidal flour;internal tide;progressive waves;standing waves;New Zealand;South Island
数据来源: Taylor
摘要:
Harmonic tidal constants, calculated from sea surface elevation observations at Jackson Bay on the West Coast of the South Island, are consistent with available semi‐diurnal and diurnal tidal phase distributions. Current observations taken over a 111 day period at mid‐depth in 1505 m of water on the southern flank of the Challenger Plateau and over a 240 day period in 1430 m of water on the South Island western coast continental slope, are subject to tidal analysis. At both sites there is a component of energy flux directed across the isobaths and only at the northern site for the M2tide is the phase consistent with a dominant progressive barotropic tide. The successive 30 day harmonic constants at the southern continental slope site exhibit a trend in the M2tidal ellipse speed and ellipticity suggesting the presence of a regular internal tide. Superposition of ‘internal tidal’ and barotropic tidal flows, as prescribed from progressive‐ and standing‐wave elevations, to fit the observations indicates that the ‘internal tide’ is probably associated with the first baroclinic mode. At the current‐meter depths the speeds of the ‘internal tide’ for the M2tide are about the same as the barotropic speeds, whereas, the S2‘internal tide’ speeds are larger than those of the barotropic tide. The consistency of the trend in ellipse parameters lends support to the theoretical progressive trapped barotropic tidal flows being a good approximation to the actual barotropic tide. Some support for the hypothesis that the S2tide on the West Coast of New Zealand has a substantial standing wave contribution is given by the northern observations, where the ratio of the S2: M2internal tidal ellipse current amplitudes are substantially larger than the ratio of the elevations, the internal tide being generated by across‐isobath flows.
点击下载:
PDF (652KB)
返 回