Variability of surface circulation in the South China Sea from satellite altimeter data

Abstract

11-year satellite altimeter sea surface height (SSH) anomaly data from January 1993 to December 2003 are used to present the dominant spatial patterns and temporal variations of the South China Sea (SCS) surface circulation through Empirical Orthogonal Function (EOF) analysis. The first three EOF modes show the obvious seasonal variations of SSH in the SCS. EOF mode one is generally characterized by a basin-wide circulation. Mode two describes the double-cell basin scale circulation structure. The two cells were located off west of the Luzon Island and southeast of Vietnam, respectively. EOF mode three presents the mesoscale eddy structure in the western SCS, which develops into a strong cyclonic eddy rapidly from July to September. EOF mode one and mode three are also embedded with interannual signals, indicating that the SCS surface circulation variation is influenced by El Niño events prominently. The strong El Niño of 1997/98 obviously changed the SCS circulation structure. This study also shows that there existed a series of mesoscale eddies in the western SCS, and their temporal variation indicates intra-seasonal and interannual signals.

The correlation of the surface circulation between the Western Pacific and the South China Sea from satellite altimetry data

“…According to the analyses of SVD, our results of the circulation modes in the SCS and WP are different from those based on EOF analyses by Guo et al (2006) -our first mode is similar to their second mode, whilst our second mode is similar to their first mode. The first reason for the difference is mainly that the studied domain limited to the west of 118 E by Guo et al (2006) is too small to include the LCE area with the largest variation in SSH in the SCS, and the correlation of the SCS with the WP is ignored (Horel 1981), which brings about the misleading modes of the SCS.…”

“…the annual mean of the expansion coefficients) occurs in 1998, 2002 and 2006; this indicates that there is an eight-year variability in the SCS and WP circulations for the first time. This is different from the so-called decadal variability in SCS circulation based on the EOF analyses of only 11-year SSH satellite altimetry data by Guo et al (2006). Before 1998, the phase is positive and the SSHs in the SCS and WP reduce.…”

“…Li et al (2004), using the Empirical Orthogonal Function (EOF) method to analyse the dynamic height near the Luzon Strait (LS), suggested that the sea surface height (SSH) variability between the SCS west of LS and the West Pacific (WP) east of LS was not obviously correlative. Using EOF analysis of only eleven-year SSH satellite altimetry data, Guo et al (2006) claimed to reveal the seasonal, interannual and decadal variability in SCS circulations. However, the application region is either only near the LS, or it is limited to the west of 118 E, whilst the region at about 118,120 E with the largest variation of SSH in the SCS, which is dominated by the Luzon Cyclonic Eddy (LCE) (Xu et al 1982), is excluded.…”

Environmental Variability Affects Distributions of Coastal Fish Species (Maryland)

“…Fangcheng coastal waters are characterized by a seasonally reversing monsoon between winter and summer (Guo et al, 2006), which may affect the hydrological features and fish distributions in this area. The effects of monsoon and oceanographic processes on coastal fish community are often strongly related to the geographical characteristics and latitude of coastal waters.…”

“…Fangcheng coastal waters, in the northern Beibu Gulf, are characterized by a seasonally reversing monsoon between winter and summer (Guo et al, 2006), which may affect the hydrological features and fish species distributions in this area. Fangcheng coastal waters provide critical habitats for many commercially important fish species by offering essential spawning, feeding, and nursery areas for one or more stages of their life history (UNEP, 2007).…”