Principal Component Analysis on Temporal-spatial Variations of Sea Level Anomalies from T/P Satellite Altimeter Data over the Northwest Pacific

Principal Component Analysis, which can reveal maximum temporal-spatial signal structure with a minimum amount of Principal Components (PCs), is used to investigate the temporal-spatial variations of sea level anomalies over the northwest Pacific. Either in S-mode or in T-mode, the sum of the variances contributed by the first 9 PCs in S-mode and by the first 3 PCs in T-mode exceeds 50% of the total amount of variation, respectively. Therefore, these PCs can reveal most of temporal-spatial pattern of sea level variations. There is a strong relationship between the El Nino and the temporal variations of the first PC either in S-mode or in T-mode, which explains the secular and inter-annual changes over the northwest Pacific. The rate of sea level change over the northwest Pacific, for the period October 1992-December 1999, is found to be negative: -0.55±0.30mm/year while in the Yellow Sea, the East China Sea and the South China Sea it is +3.4410.61 mm/year, +3.12±0.47 mm/year and -1.41±0.48 mm/year, respectively.