长江口泥质区沉积物颜色反射率指示的近百年来东亚季风变迁
摘要: 利用Minolta CM2002光谱光度计按照1 cm间隔测量了长江口泥质区ZM11孔沉积物的光谱特征，通过数理统计的方法对获取的400~700 nm可见光范围内的颜色反射率数据进行分析，揭示其对环境和气候的指示意义。因子分析提取了F1和F2两个主因子，通过与测试所得到的亮度（L）、红度（a*分量）、黄度（b*分量）等颜色反射率特征值对比，发现F1与亮度曲线的变化趋势基本一致、而F2与黄量变化趋势则完全相反，其中前者可以作为东亚夏季风的有效替代性指标，东亚夏季风强度指数增大，沉积物亮度值变大，反之亦然。结合210Pb沉积速率数据，ZM11孔沉积物颜色反射率指标记录的近百年来发生的数次东亚夏季风增强期大致出现在1887、1897、1904、1915、1936、1945、1953、1965、1977、1987、1992年，该结果得到了近年来温度和降雨量实测记录的验证。东亚季风的这种强度变化具有显著的周期性，功率谱分析表明研究区存在明显的28 a和2 a周期，结合历史资料，推断太阳辐射强度的变化是其主要控制因素，另外还可能受到大尺度气候波动的影响。
Color Reflectance Record of the Yangtze River Mud Area Sediments during the Past 100 yr and Its Implications for East Asian Monsoon Variation
Abstract: The continental shelf mud areas over the East China Sea were formed from the midHolocene, and are regarded as important places to study regional responses to global climate change due to their high sedimentation rate, which provide continual and rich record of environmental information. In this paper, the Minolta CM2002 spectrophotometer was used to measure the color reflectance data of sediments in Core MZ11, which was taken from the Yangtze River mud area. Based on the factor analysis using 400~700 nm color reflectance dada, the parameters such as F1, F2, brightness, redness and yellowness were summarized. By contrast with these curves, the results show that factor 1 and brightness show similar fluctuation patterns, while factor 2 and yellowness show complete contrary trend, so we can draw a conclusion that brightness and yellowness are the main factor to control the color composition of the sediment in core MZ11. The mud area near the Yangtze River estuary was believed to have been formed by finegrained sediments from the Yangtze River, which was influenced by the Eastern Asian Monsoon obviously, so by comparing with the historic record of the climate and the sediment brightness, we found the brightness could be a good proxy to monitor paleoclimatic changes in the study area and a time series analysis of the factor F1 and brightness indicate that relative high values in the past 100 yr occurred in 1887a, 1897a, 1904a, 1915a, 1936a, 1945a, 1953a, 1965a, 1977a, 1987a and 1992a, which may correlate with the abnormally strong summer monsoon events, suggesting that the tropical ocean had a major effect on the East Asian summer monsoon. Periodicities of 28 yr and 2 yr are observed in the color reflectance records coinciding with those known for solar cycles in the past 100 yr might be resulted from changes in solar activity.
长江口泥质区沉积物颜色反射率指示的近百年来东亚季风变迁[J]. 沉积学报, 2013, 31(2): 331-339.
| 引用本文: |
长江口泥质区沉积物颜色反射率指示的近百年来东亚季风变迁[J]. 沉积学报, 2013, 31(2): 331-339.
|
Color Reflectance Record of the Yangtze River Mud Area Sediments during the Past 100 yr and Its Implications for East Asian Monsoon Variation[J]. Acta Sedimentologica Sinica, 2013, 31(2): 331-339.
| Citation: |
Color Reflectance Record of the Yangtze River Mud Area Sediments during the Past 100 yr and Its Implications for East Asian Monsoon Variation[J]. Acta Sedimentologica Sinica, 2013, 31(2): 331-339.
|
点击查看大图
下载:
