The 41 kyr world: Milankovitch's other unsolved mystery
The 41 kyr world: Milankovitch's other unsolved mystery
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DOI：
10.1029/2002pa000791
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发表时间：
2003-03
期刊：
影响因子：
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通讯作者：
M. Raymo;K. Nisancioglu
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文献类型：
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作者：
M. Raymo;K. Nisancioglu
[1] 对于大部分北半球冰河时代，从~3.0到0.8米，全球冰量主要在地球轨道倾角的41,000年期间变化。然而，高纬度地区的夏季（或夏季热量半年）日照被广泛认为是对高纬度气候和冰量的主要影响，它主要受23,000年岁差周期的影响。因此，地质记录对我们对气候动态的理解提出了挑战。在这里，我们提出，高纬度和低纬度之间的日照梯度变化控制着上新世晚期和更新世早期的高纬度气候和冰量。由倾角驱动的高低纬度加热差异控制了大气经向热量、水分和潜能通量，这可能对米兰科维奇时间尺度上的高纬度气候产生主导控制。在通常用于研究气候长期演化的二维纬向能量平衡模型中，经向大气水分通量通常保持固定。日照梯度控制高纬度地区向极的能量通量、降水和冰量的假设从未在冰盖模型的背景下得到直接检验。根据我们对现代能量通量及其对高纬度气候的相对影响的了解，应该检查这种可能性。
[1] For most of the Northern Hemisphere Ice Ages, from ∼3.0 to 0.8 m.y., global ice volume varied predominantly at the 41,000 year period of Earth's orbital obliquity. However, summer (or summer caloric half year) insolation at high latitudes, which is widely believed to be the major influence on high-latitude climate and ice volume, is dominated by the 23,000 year precessional period. Thus the geologic record poses a challenge to our understanding of climate dynamics. Here we propose that variations in the insolation gradient between high and low latitudes control high-latitude climate and ice volume during the late Pliocene and early Pleistocene. The differential heating between high and low latitudes, driven by obliquity, controls the atmospheric meridional flux of heat, moisture, and latent energy, which may exert the dominant control on high-latitude climate on Milankovitch timescales. In the two-dimensional zonal energy balance models typically used to study the long-term evolution of climate, the meridional atmospheric moisture flux is usually kept fixed. The hypothesis that insolation gradients control the poleward energy fluxes, precipitation, and ice volume at high latitudes has never been directly examined within the context of an ice sheet model. In light of what we know about modern energy fluxes and their relative influence on high-latitude climate, this possibility should be examined.