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The article presents a study on the impacts of the Indian Ocean basin-scale sea surface temperature anomaly (SSTA) on the onset of the summer monsoon on South China Sea. It is observed that basin-wide warming in tropical Indian Ocean occurs after an El Niño event. Changes in the sea-surface temperature sustain the El Niño-Southern Oscillation (ENSO) effects towards the summer monsoon in Asia and modifies the strength of the Philippine Sea anti-cyclone, which causes delay to the South China Sea monsoon onset. The methods and the conclusion of the study are discussed.

The article presents a study on El Niño Southern Oscillation (ENSO) and the onset date of South China Sea summer monsoon (SCSSM). It mentions that the monsoon onset date (MOD) is determined by the change in direction of the zonal winds in the South China Sea from going towards the east to west in two consecutive pentads. It discusses that the ENSO is affected by the ocean heat content (OHC). The study found that the monsoon starts late in a period of warm ENSO. It also mentions that winds in the east of the Philippines affect the onset of the MOD. The study also relates the effects of cold subsurface water in the western North Pacific with SCSSM.

This paper investigates the role of intraseasonal oscillations (ISOs) in the onset of the South China Sea summer monsoon (SCSSM). Two major components of ISO (10–20‐day and 30–60‐day modes) are identified. The coupling of these two intraseasonal modes during the pre‐monsoon period of the SCSSM are investigated by examining the filtered outgoing longwave radiation (OLR), low‐level circulation, apparent heat source and apparent moisture sink from October of a previous calendar year to September of a calendar year.The zonal and meridional propagations of the 10–20‐day and 30–60‐day modes are found to be different, which reflects their different roles in the establishment and development of the SCSSM. The northwestward propagation of the 10–20‐day mode is associated with the weakening of the subtropical high over the western Pacific, while the northeastward propagation of the 30–60‐day mode originates from convection over the equatorial Indian Ocean. A hypothesis is then proposed to explain the observed variabilities in the SCSSM onset. When the equatorial Indian Ocean exhibits a 30–60‐day mode oscillation, an initially weak convection develops into a large convection band (or monsoon trough). Meanwhile, a convective disturbance of the 10–20‐day mode is induced when this monsoon trough extends to the western Pacific. These two processes then collaborate to cause a weakening of the subtropical anticyclone over the South China Sea. Because the monsoon trough associated with the 30–60‐day mode subsequently propagates northward into the Bay of Bengal (BOB), the induced vortex together with the 10–20‐day westward‐migrating convection from the equatorial western Pacific will substantially increase the effect of horizontal advection of moisture and heat, thus destabilizing the atmosphere and weakening the subtropical ridge there. Westerlies can then penetrate and prevail over the SCS region, and the SCSSM onset occurs. Copyright © 2005 Royal Meteorological Society. [ABSTRACT FROM AUTHOR]

The Taiwan Strait is the only direct passage between the South China Sea (SCS) and the East China Sea. Variations in the intensity of Kuroshio Branch and surface currents in the SCS result in seasonal and inter-annual variability in the hydrography of the SE Taiwan Strait, where the northwardly pointing funnel-like Penghu Channel is located. These currents vary with the intensity and direction of monsoons. The teleconnection between air-sea interaction of the east Pacific and west Pacific reportedly has time differences. The data in this study reveal that the salinity of the seawater in the Penghu Channel is highest during El Niño events with a seven-month lag to the monthly Niño 3.4 index, and lowest during La Niña periods, also with a lag of seven months to the monthly Niño 3.4 index. The chemical parameters also vary with these events. The concentrations of apparent oxygen utilization, nutrients, and hydrogen ions vary with the mixing ratio of SCS water and Kuroshio Branch water. The maximum concentrations of nutrients are significantly higher during the summer, seven months after a La Niña event (La Niña-7), than in other seasons. However, biological activities also affected these chemical parameters. In spring, active photosynthesis consumes more nutrients and hydrogen ion concentrations in La Niña-7 periods than in normal-7 periods. [ABSTRACT FROM AUTHOR]

The article explores the spatiotemporal features of the Indian Ocean Dipole (IOD) on the sea surface and the subsurface ocean. It was found that the previous positive IOD is associated with the normal South China Sea summer monsoon. Also, a stronger 100-hPa South Asian High is induced by a positive IOD in the summer after an IOD year. Summer rainfall in China is said to exhibit various patterns corresponding to different phases of the IOD, as influenced by the 850-hPa Asian monsoon circulations, as well as the position of the 500-hPa subtropical high ridge.

Recent advances in hydrologic optics provide a potential tool for extracting maps of optical properties of optically significant constituents. During summer experiments in the northern South China Sea, a procedure for inverting optical properties in optically complex coastal upwelling waters was performed. We tested an optical inversion model (OIM) that provides estimates of the absorption attributable to optically significant constituents (including phytoplankton, non-algal particles (NAP), colored dissolved organic matter (CDOM)), as well as the chlorophyll a concentration and the phytoplankton size class, from the total spectral absorption. The OIM provided reasonable estimates of these bio-optical products, and attempts to invert the bio-optical properties in the coastal upwelling were successful. Several bio-optical parameters displayed robust relationships to the hydrologic characteristics. The biomass was strongly enhanced in the upwelling, where the phytoplankton population was dominated by the microphytoplankton. The inherent optical properties in the surface waters delivered distinct responses to the coastal upwelling. The distribution of backscattering ratios and particulate size distribution slopes indicated that the offshore surface waters were mainly dominated by small organic NAP, while the upwelling surface water was characterized by larger particles. [ABSTRACT FROM AUTHOR]