Analysis and modeling of the seasonal South China Sea temperature cycle using remote sensing

Abstract

The present paper describes the analysis and modeling of the South China Sea (SCS) temperature cycle on a seasonal scale. It investigates the possibility to model this cycle in a consistent way while not taking into account tidal forcing and associated tidal mixing and exchange. This is motivated by the possibility to significantly increase the model's computational efficiency when neglecting tides. The goal is to develop a flexible and efficient tool for seasonal scenario analysis and to generate transport boundary forcing for local models. Given the significant spatial extent of the SCS basin and the focus on seasonal time scales, synoptic remote sensing is an ideal tool in this analysis. Remote sensing is used to assess the seasonal temperature cycle to identify the relevant driving forces and is a valuable source of input data for modeling. Model simulations are performed using a three-dimensional baroclinic-reduced depth model, driven by monthly mean sea surface anomaly boundary forcing, monthly mean lateral temperature, and salinity forcing obtained from the World Ocean Atlas 2001 climatology, six hourly meteorological forcing from the European Center for Medium range Weather Forecasting ERA-40 dataset, and remotely sensed sea surface temperature (SST) data. A sensitivity analysis of model forcing and coefficients is performed. The model results are quantitatively assessed against climatological temperature profiles using a goodness-of-fit norm. In the deep regions, the model results are in good agreement with this validation data. In the shallow regions, discrepancies are found. To improve the agreement there, we apply a SST nudging method at the free water surface. This considerably improves the model's vertical temperature representation in the shallow regions. Based on the model validation against climatological in situ and SST data, we conclude that the seasonal temperature cycle for the deep SCS basin can be represented to a good degree. For shallow regions, the absence of tidal mixing and exchange has a clear impact on the model's temperature representation. This effect on the large-scale temperature cycle can be compensated to a good degree by SST nudging for diagnostic applications.

Climate Evolution Through the Onset and Intensification of Northern Hemisphere Glaciation

“…However, $${\mathrm{U}}_{37}^{{\mathrm{K}}^{\prime }}$$ temperatures are consistently higher than Mg/Ca in the South China Sea. Strong seasonal variations in SST and mixed‐layer depth are recorded today in the South China Sea, linked to the East Asian monsoon system (Twigt et al., 2007). A summer signal from G. ruber (Lin & Hsieh, 2007) is unable to explain the cooler Mg/Ca temperatures we reconstruct relative to the (mean annual) $${\mathrm{U}}_{37}^{{\mathrm{K}}^{\prime }}$$ signal; rather, the high winter fluxes of G. ruber observed today (Lin et al., 2011) may also have imparted a relatively cool signal during the late Pliocene and early Pleistocene.…”

Analysis of Atmosphere-Ocean Interactions over South China Sea and its Relationship with Northeast Asian Precipitation Variability during Summer

“…서태평양과 인도양사이에 위치하는 남중국해는 남 동아시아에서 가장 큰 연해이다. 남중국해는 분지형 태로 평균수심은 1800 m이고 중앙 분지에서 최대수 심은 5400 m에 이른다 (Twigt et al, 2007). 남중국해 는 남동아시아 몬순 시스템에 영향을 받으며, 남중국 해 주변 지역의 바람 분포에 의하여 다양한 표층 순 환이 발생하는 것으로 알려져 있다 (Wyrtki, 1961;Shaw and Chao, 1994;Chu et al, 1999;Hu et al, 2000;Liu et al, 2001a, b;Centurioni et al, 2009).…”