环礁潟湖沉积物重建南沙群岛小冰期以来的热带气旋活动

热带气旋活动以及由此产生的风暴潮和强降雨对南海及周边沿海地区社会经济构成巨大威胁。对器测记录之前全新世热带气旋的研究有助于准确预测全球变暖背景下热带气旋活动的变化趋势。本文利用南沙群岛安乐礁潟湖沉积物重建了小冰期以来准年分辨率的热带气旋活动, 共识别28个风暴事件层。研究表明, 小冰期以来, 南沙群岛安乐礁热带气旋活动在年代际到百年尺度上频繁变化, 发育两个主要的风暴活跃期。在小冰期早期(AD 1471—1620)经历了最为强烈的风暴活跃期, 另一个风暴活跃期位于现代暖期的AD 1930—1960, 风暴活动虽有所加强, 但明显低于小冰期早期。与同期永暑礁重建结果的对比表明, 热带气旋活动存在明显的时空差异性, 更多来自相近区域的高分辨率风暴记录可有效降低古风暴活动重建的不确定性, 提高重建记录的准确度。

Reconstruction of the tropical cyclones activity in the Nansha Islands since the Little Ice Age from the atoll lagoon sediments

Tropical cyclones (TCs) and the resultant storm surges and heavy rainfall have posed huge socio-economic threats to the coastal areas of the South China Sea (SCS) and its surrounding areas. Holocene TCs studies before instrumental record help to accurately predict trends in TCs activity in the context of global warming. Here, we presented a new sub-annually resolved paleostorm record from the Anle reef lagoon sediments of the Nansha Islands in the southern SCS since the relative cold Little Ice Age (LIA) and a total of 28 storm event layers were identified. The new reconstruction indicates that the site has witnessed frequent TCs variations on a decadal to centennial-scale since the LIA, and two main storm active periods have been developed. The most intense storm activity period occurred in the early LIA (AD 1471~1620), and the other relatively active period was witnessed in the Current Warm Period (CWP) of AD 1930~1960. Although the storm activity in CWP was strengthened, it was significantly lower than that in the early LIA. Regional comparison with the storm reconstruction record of the Yongshu Reef during the same period reveals distinct spatio-temporal heterogeneity in the southern SCS. More high-resolution storm records from similar or adjacent regions could effectively reduce the uncertainty of storm reconstructions and increase the accuracy of reconstructed records.