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This study re-explores the roles of tropical SST anomalies in modulating the anomalous cyclone over the Indo-western Pacific during strong La Niña decaying years via a series of numerical experiments. The results suggest that central to eastern equatorial Pacific cooling, western north Pacific (WNP) warming, and Indian Ocean cooling all contribute to the Indo-western Pacific cyclonic wind anomalies. The WNP SST anomalies play a role via a Rossby wave-type response. As the positive SST anomalies in the WNP decay, the local forcing effect decays as well. The Indian Ocean remote forcing seems to play an important role during boreal summer via cold Kelvin wave induced cyclonic shear and boundary layer convergence. During strong La Niña decaying years, the negative SST anomalies in the equatorial central to eastern Pacific can maintain and persist into summer. Such cooling could induce anomalous Walker circulation with ascending branch over the Maritime Continent to Philippines and descending branch over central to eastern Pacific, which links the WNP climate to the equatorial central and eastern Pacific SST anomalies. The convective heating over the WNP induced remotely by central to eastern Pacific cooling in turn forces atmospheric Rossby wave to its west, which may amplify the anomalous cyclone over the Indo-western Pacific. [ABSTRACT FROM AUTHOR]

ENSO induces coherent climate anomalies over the Indo-western Pacific, but these anomalies outlast SST anomalies of the equatorial Pacific by a season, with major effects on the Asian summer monsoon. This review provides historical accounts of major milestones and synthesizes recent advances in the endeavor to understand summer variability over the Indo-Northwest Pacific region. Specifically, a large-scale anomalous anticyclone (AAC) is a recurrent pattern in post-El Ni˜no summers, spanning the tropical Northwest Pacific and North Indian oceans. Regarding the ocean memory that anchors the summer AAC, competing hypotheses emphasize either SST cooling in the easterly trade wind regime of the Northwest Pacific or SST warming in the westerly monsoon regime of the North Indian Ocean. Our synthesis reveals a coupled ocean-atmosphere mode that builds on both mechanisms in a two-stage evolution. In spring, when the northeast trades prevail, the AAC and Northwest Pacific cooling are coupled via wind-evaporation-SST feedback. The Northwest Pacific cooling persists to trigger a summer feedback that arises from the interaction of the AAC and North Indian Ocean warming, enabled by the westerly monsoon wind regime. This Indo-western Pacific ocean capacitor (IPOC) effect explains why El Ni˜no stages its last act over the monsoonal Indo-Northwest Pacific and casts the Indian Ocean warming and AAC in leading roles. The IPOC displays interdecadal modulations by the ENSO variance cycle, significantly correlated with ENSO at the turn of the 20th century and after the 1970s, but not in between. Outstanding issues, including future climate projections, are also discussed. [ABSTRACT FROM AUTHOR]

Based on the merged satellite altimeter data and in- situ observations, as well as a diagnosis of linear baroclinic Rossby wave solutions, this study analyzed the rapidly rise of sea level/sea surface height (SSH) in the tropical Pacific and Indian Oceans during recent two decades. Results show that the sea level rise signals in the tropical west Pacific and the southeast Indian Ocean are closely linked to each other through the pathways of oceanic waveguide within the Indonesian Seas in the form of thermocline adjustment. The sea level changes in the southeast Indian Ocean are strongly influenced by the low-frequency westward-propagating waves originated in the tropical Pacific, whereas those in the southwest Indian Ocean respond mainly to the local wind forcing. Analyses of the lead-lag correlation further reveal the different origins of interannual and interdecadal variabilities in the tropical Pacific. The interannual wave signals are dominated by the wind variability along the equatorial Pacific, which is associated with the El Niño-Southern Oscillation; whereas the interdecadal signals are driven mainly by the wind curl off the equatorial Pacific, which is closely related to the Pacific Decadal Oscillation. [ABSTRACT FROM AUTHOR]

Variation in intermediate water salinity in the South China Sea (SCS) between the 1960s and 1980s was studied using historical hydrographic data. The results demonstrate that the water was significantly fresher in the 1980s than in the 1960s, indicating that vertical mixing at intermediate water depth was reduced in the 1980s. This was partially because of the change of the SCS meridional overturning circulation (MOC) connecting local intermediate water with deep water. Data assimilation showed a 0.5 Sv (1 Sv=10 m /s) reduction in the strength of the MOC, which is about one third of the mean SCS MOC. Because the SCS MOC is linked to the Pacific Ocean, such an interdecadal variation in the intermediate water SCS may reflect anthropogenic climate change in the world ocean. [ABSTRACT FROM AUTHOR]