Results of PMIP2 coupled simulations of the Mid-Holocene and Last Glacial Maximum - Part 2: feedbacks with emphasis on the location of the ITCZ and mid- and high latitudes heat budget
Results of PMIP2 coupled simulations of the Mid-Holocene and Last Glacial Maximum - Part 2: feedbacks with emphasis on the location of the ITCZ and mid- and high latitudes heat budget
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DOI：
10.5194/cp-3-279-2007
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发表时间：
2007-01-01
影响因子：
4.3
通讯作者：
Zhao, Y.
中科院分区：
文献类型：
--
作者：
Braconnot, P.;Otto-Bliesner, B.;Zhao, Y.
一套耦合的海洋-大气（植被）模拟使用最先进的气候模型，现在可用于末次冰期最大期（LGM）和中全新世（MH）通过第二阶段的古气候建模相互比较项目（PMIP 2）。在这里，我们量化的纬度移动的热带辐合带（ITCZ）的位置在热带地区在北方夏季和降水的变化在北方的ITCZ的一部分。在这两个时期，大陆和东亚的变化更为明显。海洋大陆是模型之间分布最广的区域。我们还清楚地确定，夏季在MH热带大西洋的纬向温度梯度的增加越大，西非降水量的变化就越大。然而，植被反馈是不是在以前的研究中发现的大，可能是由于控制模拟模型的差异。最后，我们表明，在中高纬度的雪和海冰的反馈有助于在北方半球的LGM的冷却的一半，其余的是通过减少大气中的CO2和水蒸气。对于MH的雪和降水反馈加强春季冷却和增强北方夏季变暖，而水蒸气加强夏末变暖。这些反馈在南半球是适度的。对于末次冰期，大部分的地表冷却是由于CO2和水蒸气。
A set of coupled ocean-atmosphere(-vegetation) simulations using state of the art climate models is now available for the Last Glacial Maximum ( LGM) and the Mid-Holocene ( MH) through the second phase of the Paleoclimate Modeling Intercomparison Project ( PMIP2). Here we quantify the latitudinal shift of the location of the Intertropical Convergence Zone ( ITCZ) in the tropical regions during boreal summer and the change in precipitation in the northern part of the ITCZ. For both periods the shift is more pronounced over the continents and East Asia. The maritime continent is the region where the largest spread is found between models. We also clearly establish that the larger the increase in the meridional temperature gradient in the tropical Atlantic during summer at the MH, the larger the change in precipitation over West Africa. The vegetation feedback is however not as large as found in previous studies, probably due to model differences in the control simulation. Finally, we show that the feedback from snow and sea-ice at mid and high latitudes contributes for half of the cooling in the Northern Hemisphere for the LGM, with the remaining being achieved by the reduced CO2 and water vapour in the atmosphere. For the MH the snow and albedo feedbacks strengthen the spring cooling and enhance the boreal summer warming, whereas water vapour reinforces the late summer warming. These feedbacks are modest in the Southern Hemisphere. For the LGM most of the surface cooling is due to CO2 and water vapour.