末次冰盛期和全新世中期欧亚西风带变化的模拟分析与机制研究

The westerly study is of great importance in the climate change research during the past glacial–interglacial cycles. There is large regional variation in the westerly changes, and few studies have been performed on the modeling of the westerly in the northern hemisphere. Combining paleoclimate modeling and mechanism analyses with reconstructions, we plan to investigate the last glacial maximum (21,000 years ago) and mid-Holocene (6,000 years ago) westerly changes in position and intensity in Eurasia. The consistency and difference between different climate models as well as between multi-model and reconstructions in Eurasia will be comparatively analyzed. The dynamical mechanism for westerly changes in Eurasia under the background of the extreme cold and warm periods of the past will be explicitly revealed. Using the paleoclimate modeling experiments undertaken by the applicant, we will further explore the impact of ocean and vegetation feedbacks on the mid-Holocene westerly changes in Eurasia as well as its mechanism. The above studies will deepen our understanding to the underlying mechanism of the westerly changes in Eurasia during the past glacial–interglacials from the perspective of climate dynamics.

西风带研究对冰期—间冰期旋回气候变化研究具有重要意义。由于西风带变化具有较大区域性，且以往对北半球西风带模拟研究很少，本项目拟通过系统的古气候模拟比较分析与机制研究，结合重建工作，探索末次冰盛期（距今约21000年）和全新世中期（距今约6000年）冬、夏季欧亚西风带位置和强度变化，在欧亚区域对比分析不同模式结果之间、多模式结果与重建记录之间的一致性和主要差别，揭示过去极端冷暖时期欧亚西风带变化的动力学机制；结合申请人已开展的古气候模拟试验结果，进一步研究海洋和植被反馈作用对全新世中期欧亚西风带变化的影响及其途径。以上工作的开展，有望从气候动力学的角度加深理解冰期—间冰期欧亚西风带变化的内在机理。

中纬度西风带是全球大气环流的重要组成部分，它通过调节动量、热量、水汽和二氧化碳的输送和交换影响中纬度乃至全球气候，对冰期—间冰期旋回气候变化研究具有重要意义。由于西风带具有较大区域性，以往对北半球西风带的模拟研究十分有限，作为北半球西风带的主要组成部分，欧亚西风带变化对亚洲粉尘活动、中国黄土的形成和堆积、以及西北太平洋风成沉积均有重要的指示意义。本项目通过古气候模拟分析和机制研究，结合重建工作，深入分析了末次冰盛期和全新世中期欧亚西风带的位置和强度变化及其物理机制。研究揭示了末次冰盛期北半球西风带在高层北移、低层南移，欧亚大陆高层西风减弱，阐明了高层西风变化与副热带对流层高层降温相联，而低空急流变化主要与中纬度低层斜压性变化有关；模拟揭示了全新世中期东亚西风急流的季节性差异增大，主要表现为夏季急流显著减弱和北移，这主要源于中低纬度降水异常引起的定常波和瞬变涡旋活动异常。该研究明确了过去极端冷暖时期欧亚西风带变化及其动力学机制，填补了第四纪冰期—间冰期北半球西风带模拟研究的空白，对解译亚洲粉尘活动和中国北方黄土等地质记录提供了重要参考，从而加深了我们对东亚大气环流变化和第四纪气候演化的认识。