Different Pathways to an Early Eocene Climate
Different Pathways to an Early Eocene Climate
复制标题
形成早始新世气候的不同途径
DOI：
--
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
G. Vallis
中科院分区：
文献类型：
--
作者：
M. Henry;G. Vallis
始新世早期的特点是温度比今天高得多，赤道到两极的表面温度梯度比今天小。综合气候模式在模拟年平均气候的许多特征方面相当成功。然而，很好地模拟季节变化，特别是北极陆地温度季节性大大降低和相关的暖冬，已证明是比较困难的。此外，除了温室气体水平的增加，目前还不清楚什么是导致始新世气候的关键过程，以及是否有一个独特的因素组合，导致与现有的代理协议。在这里，我们使用一个非常灵活的大气环流模式来研究模拟气候的敏感性，CO2浓度，陆地表面特性，海洋热传输，云的范围和厚度的差异。即使在没有冰或云量变化的情况下，二氧化碳浓度的增加也会导致极地放大的表面温度变化，因为高纬度地区的水蒸气增加和对流缺乏。北极陆地上空的额外低云通常会降低夏季温度，除非二氧化碳水平非常高，否则会增加冬季温度，从而有助于实现始新世气候。考虑到植被和景观的巨大变化，陆地表面热容量的增加似乎是合理的，也降低了北极陆地的季节性。一般来说，各种不同的因素组合-高CO2水平、低层云的变化和陆地表面热容量的增加-可以导致模拟结果与当前的代用数据一致。
The early Eocene was characterised by much higher temperatures and a smaller equator-to-pole surface temperature gradient than today. Comprehensive climate models have been reasonably successful in simulating many features of that climate in the annual average. However, good simulations of the seasonal variations, and in particular the much reduced Arctic land temperature seasonality and associated much warmer winters, have proven more difficult. Further, aside from an increased level of greenhouse gases, it remains unclear what the key processes are that give rise to an Eocene climate, and whether there is a unique combination of factors that leads to agreement with available proxies. Here we use a very flexible General Circulation Model to examine the sensitivity of the modelled climate to differences in CO2 concentration, land surface properties, ocean heat transport, and cloud extent and thickness. Even in the absence of ice or changes in cloudiness, increasing the CO2 concentration leads to a polar-amplified surface temperature change because of increased water vapour and the lack of convection at high latitudes. Additional low clouds over Arctic land generally decreases summer temperatures and, except at very high CO2 levels, increases winter temperatures, thus helping achieve an Eocene climate. An increase in the land surface heat capacity, plausible given large changes in vegetation and landscape, also decreases the Arctic land seasonality. In general, various different combinations of factors -- high CO2 levels, changes in low-level clouds, and an increase in land surface heat capacity -- can lead to a simulation consistent with current proxy data.
影响因子：
5.1
作者：
Qun Liu;M. Collins;P. Maher;S. Thomson;G. Vallis
通讯作者：
Qun Liu;M. Collins;P. Maher;S. Thomson;G. Vallis
二氧化碳含量极高的气候下高纬度陆地季节性降低
DOI：
10.31223/x59k6b
发表时间：
2021
期刊：
--
影响因子：
--
作者：
Henry M
通讯作者：
Henry M