Near 7-day response of ocean bottom pressure to atmospheric surface pressure and winds in the northern South China Sea. (February 2018)

• Record Type: Journal Article
• Authors: Zhang, Kun; Zhu, Xiao-Hua; Zhao, Ruixiang
• Is Part Of: Deep sea research. Volume 132(2018)
• Page Start: 6
• Page End: 15
• Publication Date: 2018-02
• Subjects: Ocean bottom pressure -- Pressure-recording inverted echo sounder -- Atmospheric surface pressure -- Winds -- Ekman pumping/suction -- South China Sea; Oceanography -- Periodicals; Océanographie -- Périodiques; 551.4605
• DOI: 10.1016/j.dsr.2017.12.004
• Languages: English
• ISSNs: 0967-0637

Abstract

Abstract: Ocean bottom pressures, observed by five pressure-recording inverted echo sounders (PIESs) from October 2012 to July 2014, exhibit strong near 7-day variability in the northern South China Sea (SCS) where long-term in situ bottom pressure observations are quite sparse. This variability was strongest in October 2013 during the near two years observation period. By joint analysis with European Center for Medium-Range Weather Forecasts (ECMWF) data, it is shown that the near 7-day ocean bottom pressure variability is closely related to the local atmospheric surface pressure and winds. Within a period band near 7 days, there are high coherences, exceeding 95% significance level, of observed ocean bottom pressure with local atmospheric surface pressure and with both zonal and meridional components of the wind. Ekman pumping/suction caused by the meridional component of the wind in particular, is suggested as one driving mechanism. A Kelvin wave response to the near 7-day oscillation would propagate down along the continental slope, observed at the Qui Nhon in the Vietnam. By multiple and partial coherence analyses, we find that local atmospheric surface pressure and Ekman pumping/suction show nearly equal influence on ocean bottom pressure variability at near 7-day periods. A schematic diagram representing an idealized model gives us a possible mechanism to explain the relationship between ocean bottom pressure and local atmospheric forcing at near 7-day periods in the northern SCS. Highlights: Ocean bottom pressure observations in the northern South China Sea exhibit strong variability at near 7-day periods. This near 7-day variability is driven by local atmospheric surface pressure and Ekman pumping/suction caused by winds. The results of multiple and partial coherence analyses show nearly equal influence between the two factors.