Abstract Long chain alkyl diols in sediment cores were studied in the Yuedong Upwelling (YDU) area in the coastal northern South China Sea to investigate whether sea surface temperature (SST) and upwelling intensity over the last few decades can be traced by the diol-derived indices, i.e., the LDI (long chain diol index) as a proxy for SST and the DI-1 and DI-2 (diol index 1 and 2) as proxies for upwelling intensity. The influence of riverine long chain alkyl diols (e.g., 1,13- and 1,15-diols), which may affect LDI-reconstructed SSTs, was largely ruled out based on the comparison between diol distributions in suspended particulate materials in the Pearl River estuary and the core sediments. LDI-derived SSTs in downcore sediments matched well with local annual mean SSTs. The records of DI-2 changed in parallel with the local wind stress and inversely with SST at times of upwelling, suggesting that DI-2 is an effective proxy for upwelling intensity of YDU. The DI-1 showed a generally inverse variation pattern with DI-2, implying a major influence by SST, and it is thus not an applicable upwelling indicator for YDU. A negative relationship of DI-1 and a positive relationship of DI-2 with LDI-derived SST were observed. This occurrence might be attributed to El Nino–Southern Oscillation (ENSO), because the SST and upwelling intensity were largely modulated by ENSO, showing a warm annual mean SST during the years of enhanced El Nino and intensified summer upwelling.

中文翻译：

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南海北部沿岸上升流区长链烷基二醇沉积物记录

摘要 在南海北部沿海岳东上升流（YDU）地区研究了沉积岩芯中的长链烷基二醇，以研究过去几十年的海面温度（SST）和上升流强度是否可以通过二醇衍生的指数，即 LDI（长链二醇指数）作为 SST 的代表，DI-1 和 DI-2（二醇指数 1 和 2）作为上升流强度的代表。基于珠江悬浮颗粒物质中二醇分布的比较，河流长链烷基二醇（如 1,13- 和 1,15-二醇）的影响可能会影响 LDI 重建的 SSTs。河口和核心沉积物。下芯沉积物中 LDI 衍生的 SST 与当地年平均 SST 匹配良好。DI-2的记录在上升流时与当地风应力平行变化，与SST成反比，表明DI-2是YDU上升流强度的有效代表。DI-1 与 DI-2 呈现出大致相反的变化模式，表明受 SST 的主要影响，因此它不是 YDU 的适用上升流指标。观察到 DI-1 的负相关和 DI-2 与 LDI 衍生的 SST 的正相关。这种现象可能归因于厄尔尼诺-南方涛动（ENSO），因为海温和上升流强度在很大程度上受 ENSO 调制，在厄尔尼诺现象增强和夏季上升流加剧的年份显示出温暖的年平均海温。DI-1 与 DI-2 呈现出大致相反的变化模式，表明受 SST 的主要影响，因此它不是 YDU 的适用上升流指标。观察到 DI-1 的负相关和 DI-2 与 LDI 衍生的 SST 的正相关。这种现象可能归因于厄尔尼诺-南方涛动（ENSO），因为海温和上升流强度在很大程度上受 ENSO 调制，在厄尔尼诺现象增强和夏季上升流加剧的年份显示出温暖的年平均海温。DI-1 与 DI-2 呈现出大致相反的变化模式，表明受 SST 的主要影响，因此它不是 YDU 的适用上升流指标。观察到 DI-1 的负相关和 DI-2 与 LDI 衍生的 SST 的正相关。这种现象可能归因于厄尔尼诺-南方涛动（ENSO），因为海温和上升流强度在很大程度上受 ENSO 调制，在厄尔尼诺现象增强和夏季上升流加剧的年份显示出温暖的年平均海温。