Synergistic feedbacks between ocean and vegetation on mid- and high-latitude climates during the mid-Holocene
Synergistic feedbacks between ocean and vegetation on mid- and high-latitude climates during the mid-Holocene
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DOI：
10.1007/s00382-003-0379-4
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发表时间：
2004-01
期刊：
影响因子：
4.6
通讯作者：
J. Wohlfahrt;S. Harrison;P. Braconnot
中科院分区：
文献类型：
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作者：
J. Wohlfahrt;S. Harrison;P. Braconnot
IPSL大气-海洋模式与BIOME 1植被模式异步耦合的模拟显示了海洋和植被反馈及其协同作用对中高纬度（>40°N）气候的影响，以响应轨道引起的中全新世日照变化。大气对轨道强迫的反应在夏季使大陆变暖+1.2 °C，在一年中的其余时间则变冷。海洋反馈加强了春季的冷却，但抵消了秋季和冬季的冷却。植被反馈在所有季节都产生变暖，春季变化最大（+1 °C）。海洋和植被反馈之间的协同作用导致进一步变暖，这可能与这些反馈的独立影响一样大。在海洋-大气-植被模拟中，这些影响的组合导致北方高纬度地区全年都比较温暖。模拟的植被变化，导致全年变暖与观察到的中全新世植被格局是一致的。反馈也影响降水。大气对轨道强迫的反应减少了全年的降水量;最显著的变化发生在夏季的中纬度地区。海洋反馈减少了秋季、冬季和春季的干旱，但不影响夏季降水。植被反馈增加了春季降水，但放大了夏季干燥。反馈之间的协同作用增加了秋季、冬季和春季的降水，减少了夏季的降水。综合变化放大了海洋-大气-植被模拟中降水的季节性对比。夏季干旱加剧，导致温带草原不切实际地大量扩张，特别是在欧亚大陆中纬度地区。
Simulations with the IPSL atmosphere–ocean model asynchronously coupled with the BIOME1 vegetation model show the impact of ocean and vegetation feedbacks, and their synergy, on mid- and high-latitude (>40°N) climate in response to orbitally-induced changes in mid-Holocene insolation. The atmospheric response to orbital forcing produces a +1.2 °C warming over the continents in summer and a cooling during the rest of the year. Ocean feedback reinforces the cooling in spring but counteracts the autumn and winter cooling. Vegetation feedback produces warming in all seasons, with largest changes (+1 °C) in spring. Synergy between ocean and vegetation feedbacks leads to further warming, which can be as large as the independent impact of these feedbacks. The combination of these effects causes the high northern latitudes to be warmer throughout the year in the ocean–atmosphere-vegetation simulation. Simulated vegetation changes resulting from this year-round warming are consistent with observed mid-Holocene vegetation patterns. Feedbacks also impact on precipitation. The atmospheric response to orbital-forcing reduces precipitation throughout the year; the most marked changes occur in the mid-latitudes in summer. Ocean feedback reduces aridity during autumn, winter and spring, but does not affect summer precipitation. Vegetation feedback increases spring precipitation but amplifies summer drying. Synergy between the feedbacks increases precipitation in autumn, winter and spring, and reduces precipitation in summer. The combined changes amplify the seasonal contrast in precipitation in the ocean–atmosphere-vegetation simulation. Enhanced summer drought produces an unrealistically large expansion of temperate grasslands, particularly in mid-latitude Eurasia.