Date of Award

Spring 1984

Document Type


Degree Name

Master of Science (MS)


Ocean & Earth Sciences



Committee Director

Ronald E. Johnson

Committee Member

Earl C. Kindle

Committee Member

James F. Matta

Call Number for Print

Special Collections LD4331.O35T88


The distribution of Antarctic Intermediate Water at the extent of dispersion in the equatorial Pacific Ocean was investigated by means of multivariate analysis. Interrelationships among the upper intermediate water masses at this location are proposed.

Oceanographic data contained in seven cruise legs measured during the 1979-80 Hawaii to Tahiti Shuttle Experiment formed the basis of this study. Six parameters -- temperature, salinity, dissolved oxygen, phosphate, silicate and nitrate -- were used in the method of principal component analysis to classify water masses between the sea surface and 1000m. The derived water masses were compatible with previously described oceanographic features of the region. Validity of the classification was measured by Discriminant Analysis and was found to be significant.

Two salinity minimum layers were determined. A deep layer (800-1000m) corresponded to core and upper AAIW, while the shallow layer was low salinity water from both the North and South Pacific. AAIW and shallow low salinity water from the South Pacific were maintained as nearly continuous spatial and temporal features of the water structure. Low salinity water in the shallow layer from the North Pacific exhibited seasonal fluctuation in extent of intrusion and thickness. Its influence appeared to be superimposed onto that of the South Pacific shallow minimum. It is proposed that this water mass is composed of water from two sources -- subarctic Pacific and East North Pacific (via the California Current).

AAIW was found to spread into the North Pacific to 2°N-4°N as a near pure core, but beyond that extent was altered through mixing with higher salinity water above and North Pacific intermediate waters. Traces of AAIW were discernible as far north as 11°N.


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