Rapid fluctuation of alkenone temperature in the southwestern Okhotsk Sea during the past 120 ky
Rapid fluctuation of alkenone temperature in the southwestern Okhotsk Sea during the past 120 ky
复制标题
DOI：
10.1016/j.gloplacha.2006.01.010
复制
发表时间：
2004-09
影响因子：
3.9
通讯作者：
N. Harada;N. Ahagon;T. Sakamoto;M. Uchida;M. Ikehara;Y. Shibata
中科院分区：
文献类型：
--
作者：
N. Harada;N. Ahagon;T. Sakamoto;M. Uchida;M. Ikehara;Y. Shibata
鄂霍次克海冬季的海冰膨胀受到全球变暖和降温的敏感影响。在区域上，鄂霍次克海西南部与包括日本在内的东亚地区的气候变化密切相关，因为鄂霍次克海西南部的冷海表温度(SST)直接影响鄂霍次克大气高压系统的发展，而激活的鄂霍次克高压导致日本北部的寒冷气候条件。因此，鄂霍次克海的环境变化表明，作为反映全球气候变化的灵敏镜子和区域气候变化的驱动力，双向互动。为了更好地了解鄂霍次克海表层环境变化如何影响东亚气候变化，使用长链不饱和烷基酮(烷酮)温度计估计了鄂霍次克海西南部过去120 Ky年的SST，时间分辨率为千年到百年。与秋季SST至20M深度对应的烯酮温度在百年尺度上呈现反复突变，特别是在末次冰期，即距今(BP)之前的20-60M Ky期间。在格陵兰冰芯的δ18O记录中，尽管在烯酮温度记录中不能识别出一些间期温度，但烯酮温度的变化与从间期(暖事件)到间期(冷事件)的变化是同步的。小波功率谱分析表明，在10-90Ky BP期间，8Ky左右的周期性明显，在30-40Ky BP期间，表现为4-5Ky的周期性。这些周期与极地环流指数中的周期既相似又不同，极地环流指数以高纬度大气环流强度为基础，由GISP2中的主要离子浓度记录。这种相似性和差异性都表明鄂霍次克海西南部的海温主要受北半球大气-海洋环流系统的控制，而鄂霍次克海海温与格陵兰气候的关系不是线性的。冰期多次出现异常高的烯酮温度。这些温暖的烯酮温度事件可能有多种原因。特别值得一提的是，在最近一次冰川高峰期(LGM)期间，曾有报道称该研究地点附近地区的烯烃温度较高。有必要进行更多的调查，以了解末次盛会期间鄂霍次克海和邻近海域发生了什么。
Sea-ice expansion in the Okhotsk Sea in winter is sensitively affected by global warming and cooling. Regionally, the southwestern Okhotsk Sea is closely linked to climate change in East Asia, including Japan, because the cold sea surface temperature (SST) in the southwestern Okhotsk Sea influences directly the development of the Okhotsk atmospheric high-pressure system, and the activated Okhotsk high causes cold climatic conditions in northern Japan. Therefore, environmental change in the Okhotsk Sea indicates two-way interactions as a sensitive mirror reflecting global climate change and as a driving force of regional climate change. To better understand how surface environmental changes in the Okhotsk Sea can influence climate change in East Asia, SSTs were estimated in the southwestern Okhotsk Sea for the past 120 ky with millennial to centennial time resolution using the long-chain unsaturated alkyl ketone (alkenone) thermometer. The alkenone temperature, which corresponds to the SST to 20 m depth in autumn, showed repeated abrupt changes at a centennial timescale, especially during the last glacial period, 20–60 ky before present (BP). The alkenone temperature changed concurrently with changes from interstadials (warm events) to stadials (cold events) in the δ18O record of the ice cores from Greenland, although some interstadials could not be identified in the alkenone temperature record. A wavelet power spectrum analysis showed that a periodicity of about 8 ky was prominent during 10–90 ky BP, and a 4- to 5-ky cycle was characteristic during 30–40 ky BP in the alkenone temperature records. These periodicities were both similar and dissimilar to those in the Polar Circulation Index, which is based on the atmospheric circulation intensity at high latitudes, as recorded by major-ion concentrations in GISP2. Both the similarity and dissimilarity imply that the SST in the southwestern Okhotsk Sea is controlled mainly by the atmosphere–ocean circulation system in the Northern Hemisphere; however, the relationship between the SST in the Okhotsk Sea and the climate in the Greenland is not linear. Anomalously high alkenone temperatures occurred repeatedly in the glacial period. These warm alkenone temperature episodes would have had multiple causes. In particular, high alkenone temperatures during the last glacial maximum (LGM) have been reported previously for locations near this study site. More investigations are necessary to understand what happened in the Okhotsk Sea and in adjacent seas at the time of the LGM.