On sea level, temperature, and salinity variations in the central tropical Pacific and on Pacific Ocean islands

Abstract

Spectrums of oceanographic and meteorological variables are investigated for the frequency range between zero and six cycles per year. It is found that the root mean square amplitudes of the annual and nonperiodic oscillations are of the same order of magnitude. Sea level changes at neighboring islands are coherent and in phase. Changes at distant islands are coherent only at low frequencies, and their phase depends upon whether the islands are affected by the same wind regime. There is a strong and direct relation between changes of sea level and of sea temperature at low frequencies, but there is no relation between changes of sea level and of atmospheric pressure. Air temperature and sea temperature oscillations are directly related to each other, except where rainfall affects the former, in which case there is no relation. In the intratropical convergence zone a significant and inverse relation exists between air temperature and rainfall. Salinity and rainfall fluctuations are related inversely to each other, but the coherence varies considerably from island to island. Sea temperature and wind speed oscillations are related inversely to each other in the NE trade wind region. The statistical results from the island station analysis are in fair agreement with those obtained from largescale hydrographic surveys.