Cook Strait as a field for ecological study: Physical Oceanography of Cook Strait

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Cook Strait affords the only direct communication between the differing oceanographic environments of the east and west coasts of New Zealand. The hydrological pattern is complex and the limited observations available permit only a generalized view to be presented. Some localized measurements over brief periods give an indication of this complexity. The interaction of the eastern and western hydrological regimes is at present best shown by the surface temperament/salinity distribution patterns. The average summer temperatures range from 64 deg. F. in the north-west to 59 deg. F. in the south-east and a well marked temperature discontinuity is generally found in the narrow's. The average winter temperatures are 54 deg. F. in the north-west and 49 deg. F. in the south-east. The surface salinities follow the same pattern. If the discontinuity be interpreted as the boundary between waters of western and eastern affinities, its fluctuations are an index to the short term and seasonal variations in the interacting boundary zone between the two water types.