Mode of Wind and Sea Surface Temperature over the South China Sea during Rainy Season in Indonesia

Abstract

Research on near-surface wind and sea surface temperature dynamics in the South China Sea (SCS) is important to understand their impact on Indonesia's rainy season variations. In this study, we use daily wind data from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis and sea surface temperature (SST) from the Optimal Interpolated Sea Surface Temperature (OISST) during November-to-March (NDJFM) period of 2000-2016 to explore the dominant signal of temporal and spatial variations in the SCS. Results of the first EOF (EOF-1) show that the SST cooling occurred in the entire region (the South China Sea, local Indonesian sea, and the Indian Ocean nearly Sumatra), thus, is remarked as "Cold Tongue"(CT). Additionally, the CT coincides with the strengthening of northerly wind over the South China Sea (SCS) elongated in the equator's vicinity, which is indicated as a cross-equatorial north wind (CENS). For meridional wind, the spatial pattern of the EOF-1 (17.75%) shows that the strength of this CENS is associated with SCS-type (remarked as South China Sea type) of Cold Surge (CS) pathway. This CS SCS-type could enhance the Asian winter monsoon flows over Indonesia. On the other hand, the spatial pattern of the second EOF (EOF-2) shows the enhancement of the northerly wind towards the Philippine Sea (12.65%) associated with PHP-type (remarked as Filipina sea type) of CS pathway (CS PHP-type). The CS PHP-type has a relationship with strong CT (12.65%). The CT, which is observed extending southward close to the Karimata Strait, appeared not to relate to the local CENS, which occurred early. Regarding the EOF-1 results, it appeared that the correlation between northerly wind and SST in the whole of the Maritime Continent region. It also shows that the CT developed from mid-December to mid-January. On the other side, the CENS occurred from mid-December to last-February.