Characteristics of low-frequency components of the near-bottom current in the Chinese Pioneer Area

Two deep-sea moorings were deployed respec-tively in the east area and the west area of Chinese Pioneer Area (CPA) in the tropic east Pacific to monitor the regional deep-sea dynamics below 600 meters above bottom (mab) from July 1997 to Oct. 1999. Results of statistics, spectral estimate and correlation analysis of the low-passed velocity data show that time scales of low-frequency components of the near-bottom currents are 25~120 days, in which 51-day period dominates the lower band of the frequency domain. Topographic features have obvious effect on low-frequency currents below 50 mab; modulations of the bot-tom-intensified sheared mean flow to the low-frequency cur-rents are the dynamic mechanism of the frequency shift that occurs in both the east-area and the west-area.