| 千年尺度气候变率的研究 |
| |
| 引用本文： | 王绍武,谢志辉.千年尺度气候变率的研究[J].地学前缘,2002,9(1). |
| |
| 作者姓名： | 王绍武 谢志辉 |
| |
| 基金项目： | 国家重点基础研究发展计划(973计划) |
| |
| 摘 要： | 2 0世纪后期 ,千年 (ka)尺度气候变率的研究取得了重要的进展 ,这表现在以下几个方面 :(1)格陵兰冰芯及深海沉积证明 ,在末次冰期中普遍存在平均周期为 1 5ka的循环 ,有人认为全新世也存在这种循环 ,小冰期就是最近一个循环的冷期。 (2 )每个循环由 1个相对暖期 (间冰阶 )及 1个冷期(冰阶 )组成 ,称为Dansgaard/Oeshger循环 (D/O循环 )。 (3)连续几个D/O循环的冰阶气温愈来愈低 ,海因里希事件 (H事件 )就发生在最冷的冰阶之后。 (4 )自 15kaBP到 6 8kaBP共确定出 6次H事件 ,分别称为H1…H6,有的作者认为新仙女木事件 (YD)与H事件形成机制近似 ,可以称为H0 。 (5 )D/O循环与H事件的成因 ,目前尚无定论。但热盐环流 (THC)变化的学说得到了较多作者的承认。这个学说认为 :北大西洋北部的大量融冰使海面为冷的淡水控制 ,影响了大传送带中海水的下沉 ,从而削弱了深水的形成。北大西洋THC减弱 ,使向北输送的热量减少 ,使北大西洋气候更寒冷。一旦深水形成再次增加 ,完成一个D/O循环。H事件形成的机制与之类似 ,不过过程变化更为激烈。 (6 )这样 ,THC有 3种模态 :现代模 (北大西洋有两个泵 )、冰阶模 (一个泵 ) ,及H事件 (无泵 )。 (7)海洋环流模式已经对THC的变化及模态之间的转换进行了模拟 ,至少在一定程度?
|
| 关 键 词： | 千年尺度 气候变率 D/O循环 H事件 热盐环流 |
CLIMATE VARIABILITY AT MILLENNIAL TIME SCALES |
| |
| Abstract: | Significant progress has been made in studies on climate variability at millennial time scales during the last quarter of the 20th century. The following issues of the progress are outlined: (1) δ 18 O variations of Greenland ice core, and sediment data in lakes and in the North Atlantic Ocean show predominance of 1.5ka cycles during the last glacial period; (2) The D/O cycle ( Dansgaard/ Oeschger cycle ) consists of a cold stadial and a relative warm interstadial; (3) Heinrich events (H events) occurred in the culmination of stadial with time spacing between 6 and 10 or more ka; (4) Six H events were identified from 15 to 68kaBP, which were numbed as H 1 to H 6 . Younger Dryas (YD) was named as H 0 ; (5) Occurrence of D/O cycles were attributed to the changes of thermohaline circulation (THC) according which the melt water with less salinity prevented the formation of North Atlantic Deep Water (NADW), then THC was weakened, sometimes even shutdown completely. This reduced greatly the transportation of heat to the North Atlantic. Once the NADW recovered, the THC intensified again. A D/O cycle was completed. Mechanisms of formation of a H events is similar to the stadial phase in a D/O cycle, however with greater intensity; (6) So, there are three modes of THC: modern mode with two pumps, glacial mode with one pump, and no-pump mode; and (7) Numerical simulation by using of Ocean General Circulation Model(OGCM) has reproduced alternation between the three modes. Abrupt change was found with giving certain fresh water input. |
| |
| Keywords: | millennial scale climate variability Dansgaard/Oeschger cycle Heinrich events thermohaline circulation |
| 本文献已被 万方数据 等数据库收录！ |
|
