论文部分内容阅读
中晚上新世是现代气候形成过程中的关键时期。此时因为极区气候迅速变冷,北极永久冰川形成。根据在同一地区(剖面)获得的古地磁年代资料,发现山西榆社及河北泥河湾的孢粉资料记录了在松山/高斯极性事件界线附近(约2.5 Ma)的一次明显的降温事件。山西榆社的孢粉资料还记录了在约2.7 Ma-2.8 Ma的一次降温事件。这些降温事件主要是因为全球性气候变化引起的,北极圈附近和西伯利亚的冷高压大大地降低了我国,特别是我国北方的冬季气温。与此同时,位于北极圈附近的阿拉斯加发生了更为强烈的降温事件。比较两地相当时期的降温幅度,可以发现因为不同纬度的降温幅度不同使得温度的纬度变化梯度比降温事件发生前大大增加了,由原来的纬度每增加一度降低约0.3℃增大到约0.5℃。
Middle and Late Pliocene is the key period in the formation of modern climate. At this time because of rapid cooling polar region, the Arctic permanent glaciers. Based on the paleomagnetic data obtained in the same area (section), it was found that the sporopollen assemblages in Yushe, Shanxi Province and Nihewan, Hebei recorded a significant temperature drop near the Songshan / Goss Polar event boundary (about 2.5 Ma). Shanxi Yushe pollen data also recorded a cooling event at about 2.7 Ma-2.8 Ma. These cooling events are mainly caused by global climate change. The cold high pressure around the Arctic Circle and Siberia has greatly reduced the winter temperatures in our country, especially in northern China. In the meantime, a more intense cooling off took place in Alaska, near the Arctic Circle. Comparing the temperature drop rates of the two places during the same period, we can see that the gradient of temperature change greatly increases from about 0.3 ° C for each increase of about 0.5 ° C .