An atmospheric general circulation model (AGCM) and an oceanic general circulation model (OGCM) are asynchronously coupled to simulate the climate of the mid-Holocene period. The role of the solar radiation and ocean ...An atmospheric general circulation model (AGCM) and an oceanic general circulation model (OGCM) are asynchronously coupled to simulate the climate of the mid-Holocene period. The role of the solar radiation and ocean in the mid-Holocene East Asian monsoon climate is analyzed and some mechanisms are revealed. At the forcing of changed solar radiation induced by the changed orbital parameters and the changed SST simulated by the OGCM, compared with when there is orbital forcing alone, there is more precipitation and the monsoon is stronger in the summer of East Asia, and the winter temperature increases over China. These agree better with the reconstructed data. It is revealed that the change of solar radiation can displace northward the ITCZ and the East Asia subtropical jet, which bring more precipitation over the south of Tibet and North and Northeast China. By analyzing the summer meridional latent heat transport, it is found that the influence of solar radiation change is mainly to increase the convergence of atmosphere toward the land, and the influence of SST change is mainly to transport more moisture to the sea surface atmosphere. Their synergistic effect on East Asian precipitation is much stronger than the sum of their respective effects.展开更多
This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the inter...This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the international community. In historical climate simulations, changes in solar radiation and volcanic activity explain most parts of reconstructions over the last millennium prior to the industrial era, while atmospheric greenhouse gas concentrations play the most important role in the20 th century warming over China. There is a considerable model–data mismatch in the annual and boreal winter temperature change over China during the mid-Holocene [6000 years before present（ka BP）], while coupled models with an interactive ocean generally perform better than atmospheric models. For the Last Glacial Maximum（21 ka BP）, climate models successfully reproduce the surface cooling trend over China but fail to reproduce its magnitude, with a better performance for coupled models. At that time, reconstructed vegetation and western Pacific sea surface temperatures could have significantly affected the East Asian climate, and environmental conditions on the Qinghai–Tibetan Plateau were most likely very different to the present day. During the late Marine Isotope Stage 3（30–40 ka BP）, orbital forcing and Northern Hemisphere glaciation, as well as vegetation change in China, were likely responsible for East Asian climate change. On the tectonic scale,the Qinghai–Tibetan Plateau uplift, the Tethys Sea retreat, and the South China Sea expansion played important roles in the formation of the East Asian monsoon-dominant environment pattern during the late Cenozoic.展开更多
By using a 9-level global atmospheric general circulation model developed at the Institute of Atmospheric Physics （IAP9L-AGCM） under the Chinese Academy of Sciences, the authors investigated the response of the East...By using a 9-level global atmospheric general circulation model developed at the Institute of Atmospheric Physics （IAP9L-AGCM） under the Chinese Academy of Sciences, the authors investigated the response of the East Asian monsoon climate to changes both in orbital forcing and the snow and glaciers over the Tibetan Plateau at the mid-Holocene, about 6000 calendar years before the present （6 kyr BP）. With the Earth＇s orbital parameters appropriate for the mid-Holocene, the IAP9L-AGCM computed warmer and wetter conditions in boreal summer than for the present day. Under the precondition of continental snow and glacier cover existing over part of the Tibetan Plateau at the mid-Holocene, the authors examined the regional climate response to the Tibetan Plateau cooling. The simulations indicated that climate changes in South Asia and parts of central Asia as well as in East Asia are sensitive to the Tibetan Plateau cooling at the mid-Holocene, showing a significant decrease in precipitation in northern India, northern China and southern Mongolia and an increase in Southeast Asia during boreal summer. The latter seems to correspond to the weakening, southeastward shift of the Asian summer monsoon system resulting from reduced heat contrast between the Eurasian continent and the Pacific and Indian Oceans when a cooling over the Tibetan Plateau was imposed. The simulation results suggest that the snow and glacier environment over the Tibetan Plateau is an important factor for mid-Holocene climate change in the areas highly influenced by the Asian monsoon.展开更多
Tectonic uplift of the Tibetan Plateau(TP) is a major event in the recent geological history of the earth,which produced far-reaching impacts on the Asian and global climates and environments.Since the 1970 s,with the...Tectonic uplift of the Tibetan Plateau(TP) is a major event in the recent geological history of the earth,which produced far-reaching impacts on the Asian and global climates and environments.Since the 1970 s,with the development of theories in planetary fluid dynamics and the improvement of computational environment,numerical simulation based on general circulation models(GCMs) has become an increasingly effective tool in investigations of the physical mechanisms and evolutionary processes of paleoclimate associated with the TP uplift.In this paper,we provide a timely review on representative works in the past four decades on the paleoclimatic responses to the plateau uplift.Numerical simulations to study the paleoclimatic effects of the plateau uplift experienced three stages with increasing complexity:1) plateau uplift as a whole in a single episode,as represented by the no-mountain/with-mountain experiments;2) phased uplift in which the uplifting process was divided into multiple stages and within each the plateau rose by a certain proportion of its current height;and3) sub-regional uplift,in which the focus was the effects of the uplift of a certain area within the TP,such as the northern Tibetan Plateau.These studies discovered the cause-effect relations between the plateau uplift and paleoclimate change,especially for the effects on the evolution of Asian monsoon system and aridification of inland Asia.In this review,we also included examples of current on-going studies,such as the relative impacts of the Himalayas vs.those of the TP as the rain barrier and comparative studies on the paleoclimatic effects of the uplifts of the TP and African highland.Toward the end,we identified five areas as the focus of future research regarding the TP uplift:1) the differences in the evolutionary processes of the South Asian and East Asian monsoons in response to the Himalayas-TP uplift at the regional and sub-regional scales;2) climatic feedbacks;3) long-distance effects(teleconnections) of the TP uplift;4) abrupt clim展开更多
Whether there were more extensive glaciations during the Marine Isotope Stage(MIS)3 relative to MIS 2 across the Tian Shan in Central Asia is intensely debated because of the uncertainty in chronological data and full...Whether there were more extensive glaciations during the Marine Isotope Stage(MIS)3 relative to MIS 2 across the Tian Shan in Central Asia is intensely debated because of the uncertainty in chronological data and fully understanding the driving mechanisms.To help resolve the ongoing debate,we assess the climate sensitivity of the glaciers and reconstruct the extent of glaciation during MIS 2 and 3 across the Tian Shan,using a glacier-resolving(250×250 m)ice sheet model asynchronously coupled with a global climate model.Our results demonstrate that the equilibrium-line altitude(ELA)over the Tian Shan decreases by∼180 m for every 1°C cooling under a modern precipitation regime,but precipitation reduction greatly lowers the sensitivity of the glaciers to temperature decrease(e.g.,the effect of 2°C cooling is broadly offset by a 50%decrease in precipitation).Under the modeled colder/drier-than-present climate,the model predicts an ELA depression(∆ELA)of∼75 m(162 m)over the Tian Shan during MIS 3 interstadials(stadials).The extent of MIS 3 glaciation is much smaller than that during MIS 2(i.e.,∆ELA=∼726 m).The more extensive glaciation during MIS 2 is largely attributed to the enhanced summer cooling.Furthermore,through a site-to-site model-data comparison,we find that the closest match between the modeled glacier margin and the locations of the glacial deposits previously argued to be MIS 3 is generally achieved under MIS 2 climatic conditions.These results suggest more extensive glacier advances over the Tian Shan during MIS 2 than MIS 3 on a regional scale,although MIS 3 glaciation may still occur in individual glacier catchments.This pattern suggests general synchronicity with the timing of maximum Northern Hemisphere ice sheets during the last glacial,which should be further tested in a multimodel framework in the future.展开更多
明末清初中国社会动荡加剧,王朝更迭,伴随着华北地区较为明显的年代际气候变化。本研究使用CESM-LME(CESM Last Millennium Ensemble)模拟数据,结合重建证据,对明末清初华北夏季降水年代际气候变化特征和原因进行了分析。重建证据显示,1...明末清初中国社会动荡加剧,王朝更迭,伴随着华北地区较为明显的年代际气候变化。本研究使用CESM-LME(CESM Last Millennium Ensemble)模拟数据,结合重建证据,对明末清初华北夏季降水年代际气候变化特征和原因进行了分析。重建证据显示,1644年华北夏季降水发生由少到多的年代际转变,中国东部夏季降水呈“南旱北涝”的变化格局。CESM-LME集合试验成员012能够模拟出这样的年代际转变,但模拟的变化幅度偏弱且转变发生时间略晚。模拟显示,北太平洋出现类PDO(Pacific Decadal Oscillation,太平洋年代际振荡)正位相的海温年代际异常,引起日本海附近低压异常。同时,热带太平洋呈现类拉尼娜型海温异常,使得菲律宾以东洋面对流增强、降水增加,通过北传罗斯贝波激发类东亚-太平洋遥相关,导致西北太平洋副热带高压增强西伸和日本海附近异常低压的加强。对应于这样的环流异常,华北有北风异常,长江以南有南风异常,华北地区南部水汽辐合增强,有异常的上升运动,华北夏季降水年代际增多,并伴随着东亚副热带西风急流的向南移动。伴随华北夏季降水年代际转变,华北土地承载力提高,社会系统逐渐恢复和稳定。展开更多
Reconstructing past climate is beneficial for researchers to understand the mechanism of past climate change, recognize the context of modern climate change and predict scenarios of future climate change. Paleoclimate...Reconstructing past climate is beneficial for researchers to understand the mechanism of past climate change, recognize the context of modern climate change and predict scenarios of future climate change. Paleoclimate data assimilation(PDA), which was first introduced in 2000, is a promising approach and a significant issue in the context of past climate research. PDA has the same theoretical basis as the traditional data assimilation(DA) employed in the fields of atmosphere science, ocean science and land surface science. The main aim of PDA is to optimally estimate past climate states that are both consistent with the climate signal recorded in proxy and the dynamic understanding of the climate system through combining the physical laws and dynamic mechanisms of climate systems represented by climate models with climate signals recorded in proxies(e.g., tree rings, ice cores). After investigating the research status and latest advances of PDA abroad, in this paper, the background, concept and methodology of PAD are briefly introduced. Several special aspects and the development history of PAD are systematically summarized. The theoretical basis and typical cases associated with three frequently-used PAD methods(e.g., nudging, particle filter and ensemble square root filter) are analyzed and demonstrated. Finally, some underlying problems in current studies and key prospects in future research related to PDA are proposed to provide valuable thoughts on and a scientific basis for PDA research.展开更多
基金supported by the National Outstanding Youth Foundation under Grant No.40125014the Chinese Academy of Sciences Key Project under Grant KZCX3-AW-133.
文摘An atmospheric general circulation model (AGCM) and an oceanic general circulation model (OGCM) are asynchronously coupled to simulate the climate of the mid-Holocene period. The role of the solar radiation and ocean in the mid-Holocene East Asian monsoon climate is analyzed and some mechanisms are revealed. At the forcing of changed solar radiation induced by the changed orbital parameters and the changed SST simulated by the OGCM, compared with when there is orbital forcing alone, there is more precipitation and the monsoon is stronger in the summer of East Asia, and the winter temperature increases over China. These agree better with the reconstructed data. It is revealed that the change of solar radiation can displace northward the ITCZ and the East Asia subtropical jet, which bring more precipitation over the south of Tibet and North and Northeast China. By analyzing the summer meridional latent heat transport, it is found that the influence of solar radiation change is mainly to increase the convergence of atmosphere toward the land, and the influence of SST change is mainly to transport more moisture to the sea surface atmosphere. Their synergistic effect on East Asian precipitation is much stronger than the sum of their respective effects.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB03020602)supported by the Key Directional Program of the Knowledge-innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2–YW–338– 2)+2 种基金supported by the National Basic Research Program of China (Grant No. 2007CB815901)supported by the National Basic Research Program of China (Grant No. 2010CB950102)supported by the National Natural Science Foundation of China (Grant No. 40875043)
文摘This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the international community. In historical climate simulations, changes in solar radiation and volcanic activity explain most parts of reconstructions over the last millennium prior to the industrial era, while atmospheric greenhouse gas concentrations play the most important role in the20 th century warming over China. There is a considerable model–data mismatch in the annual and boreal winter temperature change over China during the mid-Holocene [6000 years before present（ka BP）], while coupled models with an interactive ocean generally perform better than atmospheric models. For the Last Glacial Maximum（21 ka BP）, climate models successfully reproduce the surface cooling trend over China but fail to reproduce its magnitude, with a better performance for coupled models. At that time, reconstructed vegetation and western Pacific sea surface temperatures could have significantly affected the East Asian climate, and environmental conditions on the Qinghai–Tibetan Plateau were most likely very different to the present day. During the late Marine Isotope Stage 3（30–40 ka BP）, orbital forcing and Northern Hemisphere glaciation, as well as vegetation change in China, were likely responsible for East Asian climate change. On the tectonic scale,the Qinghai–Tibetan Plateau uplift, the Tethys Sea retreat, and the South China Sea expansion played important roles in the formation of the East Asian monsoon-dominant environment pattern during the late Cenozoic.
基金This research was supported by the Na- tional Natural Science Foundation of China （NSFC） （Grant No. 40571169） the NSFC Innovation Team Project （Grant No. 40421101）.
文摘By using a 9-level global atmospheric general circulation model developed at the Institute of Atmospheric Physics （IAP9L-AGCM） under the Chinese Academy of Sciences, the authors investigated the response of the East Asian monsoon climate to changes both in orbital forcing and the snow and glaciers over the Tibetan Plateau at the mid-Holocene, about 6000 calendar years before the present （6 kyr BP）. With the Earth＇s orbital parameters appropriate for the mid-Holocene, the IAP9L-AGCM computed warmer and wetter conditions in boreal summer than for the present day. Under the precondition of continental snow and glacier cover existing over part of the Tibetan Plateau at the mid-Holocene, the authors examined the regional climate response to the Tibetan Plateau cooling. The simulations indicated that climate changes in South Asia and parts of central Asia as well as in East Asia are sensitive to the Tibetan Plateau cooling at the mid-Holocene, showing a significant decrease in precipitation in northern India, northern China and southern Mongolia and an increase in Southeast Asia during boreal summer. The latter seems to correspond to the weakening, southeastward shift of the Asian summer monsoon system resulting from reduced heat contrast between the Eurasian continent and the Pacific and Indian Oceans when a cooling over the Tibetan Plateau was imposed. The simulation results suggest that the snow and glacier environment over the Tibetan Plateau is an important factor for mid-Holocene climate change in the areas highly influenced by the Asian monsoon.
基金National Natural Science Foundation of China(Grant Nos.40825008,41075067,40921120406)the National Basic Research Program of China(Grant No.2010CB833406)
文摘Tectonic uplift of the Tibetan Plateau(TP) is a major event in the recent geological history of the earth,which produced far-reaching impacts on the Asian and global climates and environments.Since the 1970 s,with the development of theories in planetary fluid dynamics and the improvement of computational environment,numerical simulation based on general circulation models(GCMs) has become an increasingly effective tool in investigations of the physical mechanisms and evolutionary processes of paleoclimate associated with the TP uplift.In this paper,we provide a timely review on representative works in the past four decades on the paleoclimatic responses to the plateau uplift.Numerical simulations to study the paleoclimatic effects of the plateau uplift experienced three stages with increasing complexity:1) plateau uplift as a whole in a single episode,as represented by the no-mountain/with-mountain experiments;2) phased uplift in which the uplifting process was divided into multiple stages and within each the plateau rose by a certain proportion of its current height;and3) sub-regional uplift,in which the focus was the effects of the uplift of a certain area within the TP,such as the northern Tibetan Plateau.These studies discovered the cause-effect relations between the plateau uplift and paleoclimate change,especially for the effects on the evolution of Asian monsoon system and aridification of inland Asia.In this review,we also included examples of current on-going studies,such as the relative impacts of the Himalayas vs.those of the TP as the rain barrier and comparative studies on the paleoclimatic effects of the uplifts of the TP and African highland.Toward the end,we identified five areas as the focus of future research regarding the TP uplift:1) the differences in the evolutionary processes of the South Asian and East Asian monsoons in response to the Himalayas-TP uplift at the regional and sub-regional scales;2) climatic feedbacks;3) long-distance effects(teleconnections) of the TP uplift;4) abrupt clim
基金funded by the National Natural Science Foundation of China(42022036,41888101)the Youth Innovation Promotion Association by CAS(2019080).
文摘Whether there were more extensive glaciations during the Marine Isotope Stage(MIS)3 relative to MIS 2 across the Tian Shan in Central Asia is intensely debated because of the uncertainty in chronological data and fully understanding the driving mechanisms.To help resolve the ongoing debate,we assess the climate sensitivity of the glaciers and reconstruct the extent of glaciation during MIS 2 and 3 across the Tian Shan,using a glacier-resolving(250×250 m)ice sheet model asynchronously coupled with a global climate model.Our results demonstrate that the equilibrium-line altitude(ELA)over the Tian Shan decreases by∼180 m for every 1°C cooling under a modern precipitation regime,but precipitation reduction greatly lowers the sensitivity of the glaciers to temperature decrease(e.g.,the effect of 2°C cooling is broadly offset by a 50%decrease in precipitation).Under the modeled colder/drier-than-present climate,the model predicts an ELA depression(∆ELA)of∼75 m(162 m)over the Tian Shan during MIS 3 interstadials(stadials).The extent of MIS 3 glaciation is much smaller than that during MIS 2(i.e.,∆ELA=∼726 m).The more extensive glaciation during MIS 2 is largely attributed to the enhanced summer cooling.Furthermore,through a site-to-site model-data comparison,we find that the closest match between the modeled glacier margin and the locations of the glacial deposits previously argued to be MIS 3 is generally achieved under MIS 2 climatic conditions.These results suggest more extensive glacier advances over the Tian Shan during MIS 2 than MIS 3 on a regional scale,although MIS 3 glaciation may still occur in individual glacier catchments.This pattern suggests general synchronicity with the timing of maximum Northern Hemisphere ice sheets during the last glacial,which should be further tested in a multimodel framework in the future.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91425303, 91225302)the Chinese Academy of Sciences Interdisciplinary Innovation Team Project
文摘Reconstructing past climate is beneficial for researchers to understand the mechanism of past climate change, recognize the context of modern climate change and predict scenarios of future climate change. Paleoclimate data assimilation(PDA), which was first introduced in 2000, is a promising approach and a significant issue in the context of past climate research. PDA has the same theoretical basis as the traditional data assimilation(DA) employed in the fields of atmosphere science, ocean science and land surface science. The main aim of PDA is to optimally estimate past climate states that are both consistent with the climate signal recorded in proxy and the dynamic understanding of the climate system through combining the physical laws and dynamic mechanisms of climate systems represented by climate models with climate signals recorded in proxies(e.g., tree rings, ice cores). After investigating the research status and latest advances of PDA abroad, in this paper, the background, concept and methodology of PAD are briefly introduced. Several special aspects and the development history of PAD are systematically summarized. The theoretical basis and typical cases associated with three frequently-used PAD methods(e.g., nudging, particle filter and ensemble square root filter) are analyzed and demonstrated. Finally, some underlying problems in current studies and key prospects in future research related to PDA are proposed to provide valuable thoughts on and a scientific basis for PDA research.
