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Effect of increasing Arctic river runoff on the atlantic meridional overturning circulation:a model study

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Acta Oceanologica Sinica 2017年第8期36卷 59-65页

作者： SHU Qi QIAO Fangli SONG Zhenya XIAO Bin The First Institute of Oceanography State Oceanic AdministrationQingdao 266061China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China Key Laboratory of Marine Science and Numerical Modeling State Oceanic AdministrationQingdao 266061China

An increasing amount of freshwater has been observed to enter the Arctic Ocean from the six largest Eurasian rivers over the past several decades. The increasing trend is projected to continue in the twenty-first century according to Coupled Model Intercomparison Project Phase 5 （CMIP5） coupled models. The present study found that water flux from rivers to the Arctic Ocean at the end of the century will be 1.4 times that in 1950 according to CMIP5 projection results under Representative Concentration Pathway 8.5. The effect of increasing Arctic river runoff on the atlantic meridional overturning circulation （AMOC） was investigated using an ocean-ice coupled model. Results obtained from two numerical experiments show that 100, 150 and 200 years after the start of an increase in the Arctic river runoff at a rate of 0.22%/a, the AMOC will weaken by 0.6 （3%）, 1.2 （7%） and 1.8 （11%） Sv. AMOC weakening is mainly caused by freshwater transported from increasing Arctic river runoff inhibiting the formation of North atlantic Deep Water （NADW）. As the AMOC weakens, the deep seawater age will become older throughout the atlantic Basin owing to the increasing of Arctic runoff.

关键词： climate change Arctic river runoff atlantic meridional overturning circulation

Arctic Climate Changes Based on Historical Simulations(1900-2013) with the CAMS-CSM

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Journal of Meteorological Research 2018年第6期32卷 881-895页

作者： Ting WEI Jian LI Xinyao RONG Wenjie DONG Bingyi WU Minghu DING State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences School of Atmospheric Sciences Sun Yat-Sen University Zhuhai Joint Innovative Center for Climate–Environment–Ecosystem Future Earth Research InstituteBeijing Normal University Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences Institute of Atmospheric Sciences Fudan University

The Chinese Academy of Meteorological Sciences Climate System Model(CAMS-CSM) is a newly developed global climate model that will participate in the Coupled Model Intercomparison Project phase 6. Based on historical simulations(1900-2013), we evaluate the model performance in simulating the observed characteristics of the Arctic climate system, which includes air temperature, precipitation, the Arctic Oscillation(AO), ocean temperature/salinity,the atlantic meridional overturning circulation(AMOC), snow cover, and sea ice. The model-data comparisons indicate that the CAMS-CSM reproduces spatial patterns of climatological mean air temperature over the Arctic(60°-90°N) and a rapid warming trend from 1979 to 2013. However, the warming trend is overestimated south of the Arctic Circle, implying a subdued Arctic amplification. The distribution of climatological precipitation in the Arctic is broadly captured in the model, whereas it shows limited skills in depicting the overall increasing trend. The AO can be reproduced by the CAMS-CSM in terms of reasonable patterns and variability. Regarding the ocean simulation, the model underestimates the AMOC and zonally averaged ocean temperatures and salinity above a depth of 500 m, and it fails to reproduce the observed increasing trend in the upper ocean heat content in the Arctic. The largescale distribution of the snow cover extent(SCE) in the Northern Hemisphere and the overall decreasing trend in the spring SCE are captured by the CAMS-CSM, while the biased magnitudes exist. Due to the underestimation of the AMOC and the poor quantification of air–sea interaction, the CAMS-CSM overestimates regional sea ice and underestimates the observed decreasing trend in Arctic sea–ice area in September. Overall, the CAMS-CSM reproduces a climatological distribution of the Arctic climate system and general trends from 1979 to 2013 compared with the observations, but it shows limited skills in modeling local trends and interannual variab

关键词： temperature precipitation Arctic Oscillation atlantic meridional overturning circulation ocean potential temperature salinity snow cover sea ice

Land–atmosphere–ocean coupling associated with the Tibetan Plateau and its climate impacts

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National Science Review 2020年第3期7卷 534-552页

作者： Yimin Liu Mengmeng Lu Haijun Yang Anmin Duan Bian He Song Yang Guoxiong Wu State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences (CAS) College of Earth Science University of Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences School of Atmospheric Sciences& Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen University Department of Earth and Planetary Sciences Harvard University Laboratory for Climate and Ocean-Atmosphere Studies (LaCOAS) and Department of Atmospheric and Oceanic Sciences School of PhysicsPeking University Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)

This paper reviews recent advances regarding land–atmosphere–ocean coupling associated with the Tibetan Plateau(TP) and its climatic impacts. Thermal forcing over the TP interacts strongly with that over the Iranian Plateau, forming a coupled heating system that elevates the tropopause, generates a monsoonal meridional circulation over South Asia and creates conditions of large-scale ascent favorable for Asian summer monsoon development. TP heating leads to intensification and westward extension(northward movement) of the South Asian High(atlantic Intertropical Convergence Zone), and exerts strong impacts on upstream climate variations from North atlantic to West Asia. It also affects oceanic circulation and buoyancy fields via atmospheric stationary wave trains and air–sea interaction processes, contributing to formation of the atlantic meridional overturning circulation. The TP thermal state and atmospheric–oceanic conditions are highly interactive and Asian summer monsoon variability is controlled synergistically by internal TP variability and external forcing factors.

关键词： Tibetan and Iranian Plateau system atmospheric heat source Asian summer monsoon upstream climate atlantic meridional overturning circulation

Response of ocean climate to different heat-flux perturbations over the North atlantic in FAFMIP

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Advances in Climate Change Research 2023年第4期14卷 546-559页

作者： Wen-Yu YIN Xin GAO Run GUO Peng FAN Guang-Qing ZHOU International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

The diversity of surface-flux perturbations,especially for heat-flux perturbations,notably leads to uncertainties surrounding the responses of ocean climate under global warming scenarios projected by climate/Earth system ***,when imposing heat-flux perturbations on the models,strong feedback persists between the atmosphere and the ocean,resulting in nearly doubled heat-flux perturbation over the North atlantic(NA).Herein,quantitative evaluation of the influences of magnitude change of heat-flux perturbations over the NA on the changes in the atlantic meridional overturning circulation(AMOC),ocean heat uptake(OHU)and dynamic sea level(DSL)has been conducted by analysis of eight coupled model responses to the heat-flux perturbation experiments in the Flux-Anomaly-Forced Model Inter-comparison *** has been demonstrated that the magnitude of the AMOC change is extremely sensitive to the magnitude change of imposed NA heat-flux perturbation,and the weakening amplitude of the AMOC is nearly halved as the imposed heat-flux perturbation F is halved over the *** most remarkable responses of both DSL and OHU to the magnitude changes of NA heat-flux perturbation have been primarily found in the atlantic and Arctic basins,especially for the NA *** the added ocean heat uptake(OHUa)and redistributed ocean heat uptake(OHUr)play key roles in OHU changes among the various NA heat-flux perturbation *** magnitude change of NA-mean OHUa is almost linearly related to the imposed NA heat-flux perturbation,while the magnitude change of NA-mean OHUr,which is primarily caused by AMOC change and redistributed heat flux,is not proportional to the imposed NA heat-flux *** is a nearly linear relationship between the magnitude of AMOC change and the OHUr in tropical regions,including the regions in the low-latitude South atlantic,the tropical Pacific Ocean and the Indian Ocean.

关键词： Heat-flux perturbation Ocean heat uptake North atlantic atlantic meridional overturning circulation Coupled general circulation model

Role of Ocean Dynamics in the Seasonal Hadley Cell:A Response to Idealized Arctic Amplification

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Advances in Atmospheric Sciences 2023年第12期40卷 2211-2223页

作者： Haijin DAI Qiang YAO College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China

How atmospheric and oceanic circulations respond to Arctic warming at different timescales are revealed with idealized numerical *** by local forcing and feedback,Arctic warming appears and leads to sea-ice ***-water formation is inhibited,which weakens the atlantic meridional overturning circulation(AMOC).The flow and temperature in the upper layer does not respond to the AMOC decrease immediately,especially at mid-low ***,nearly uniform surface warming in mid-low latitudes enhances(decreases)the strength(width)of the Hadley cell(HC).With the smaller northward heat carried by the weaker AMOC,the Norwegian Sea cools *** strong warming in Northern Hemisphere high latitudes,the long-term response triggers the“temperature-wind-gyre-temperature”cycle,leading to colder midlatitudes,resulting in strong subsidence and Ferrel cell enhancement,which drives the HC *** weaker warming in the tropics and stronger warming at high latitudes,there is a stronger HC with decreased width.A much warmer Southern Hemisphere appears due to a weaker AMOC that also pushes the HC *** idealized model results suggest that the HC strengthens under both warming conditions,as tropical warming determines the strength of the HC ***,extreme Arctic warming led by artificially reduced surface albedo decreases the meridional temperature gradient between high and low latitudes,which contracts the ***,a warmer mid-high latitude in the Northern(Southern)Hemisphere due to surface albedo feedback(weakened AMOC)in our experiments pushes the HC northward(southward).In most seasons,the HC exhibits the same trend as that described above.

关键词： Hadley cell Arctic amplification Southern Hemisphere warming atlantic meridional overturning circulation

The influence of explicit tidal forcing in a climate ocean circulation model

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Acta Oceanologica Sinica 2016年第9期35卷 42-50页

作者： YU Yi LIU Hailong LAN Jian Physical Oceanography Laboratory Qingdao Collaborative Innovation Center of Marine Science and TechnologyOcean University of China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

The eight main tidal constituents have been implemented in the global ocean general circulation model with approximate 1° horizontal *** with the observation data,the patterns of the tidal amplitudes and phases had been simulated fairly *** responses of mean circulation,temperature and salinity are further investigated in the global *** implementing the tidal forcing,wind-driven circulations are reduced,especially those in coastal *** is also found that the upper cell transport of the atlantic meridional overturning circulation（AMOC） reduces significantly,while its deep cell transport is slightly enhanced from 9×106m3/s to 10×106 m3/*** changes of circulations are all related to the increase of a bottom friction and a vertical viscosity due to the tidal *** temperature and salinity of the model are also significantly affected by the tidal forcing through the enhanced bottom friction,mixing and the changes in mean *** largest changes occur in the coastal regions,where the water is cooled and *** the open ocean,the changes are divided into three layers：cooled and freshened on the surface and below 3 000 m,and warmed and salted in the middle in the open *** the upper two layers,the changes are mainly caused by the enhanced mixing,as warm and salty water sinks and cold and fresh water rises;whereas in the deep layer,the enhancement of the deep overturning circulation accounts for the cold and fresh changes in the deep ocean.

关键词： tidal forcing tidal mixing ocean general circulation model wind-driven circulation atlantic meridional overturning circulation

Ocean Response to a Climate Change Heat-Flux Perturbation in an Ocean Model and Its Corresponding Coupled Model

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Advances in Atmospheric Sciences 2022年第1期39卷 55-66页

作者： Jiangbo JIN Xiao DONG Juanxiong HE Yi YU Hailong LIU Minghua ZHANG Qingcun ZENG He ZHANG Xin GAO Guangqing ZHOU Yaqi WANG International Center for climate and Environment Sciences(ICCES) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100049China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100049China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China School of Marine and Atmospheric Sciences Stony Brook UniversityStony BrookNew YorkNY 11790USA

State-of-the-art coupled general circulation models(CGCMs)are used to predict ocean heat uptake(OHU)and sealevel change under global ***,the projections of different models vary,resulting in high *** of the inter-model spread is driven by responses to surface heat *** study mainly focuses on the response of the ocean to a surface heat flux perturbation F,as prescribed by the Flux-Anomaly-Forced Model Intercomparison Project(FAFMIP).The results of ocean model were compared with those of a CGCM with the same ocean *** the global scale,the changes in global mean temperature,ocean heat content(OHC),and steric sea level(SSL)simulated in the OGCM are generally consistent with CGCM *** in changes in ocean temperature,OHC,and SSL between the two models primarily occur in the Arctic and atlantic Oceans(AA)and the Southern Ocean(SO)*** addition to the differences in surface heat flux anomalies between the two models,differences in heat exchange between basins also play an important role in the inconsistencies in ocean climate changes in the AA and SO *** discrepancies are largely due to both the larger initial value and the greater weakening change of the atlantic meridional overturning circulation(AMOC)in *** greater weakening of the AMOC in the CGCM is associated with the atmosphere–ocean feedback and the lack of a restoring salinity boundary ***,differences in surface salinity boundary conditions between the two models contribute to discrepancies in SSL changes.

关键词： ocean heat uptake atlantic meridional overturning circulation ocean general circulation model coupled general circulation model

The impact of oceanic processes on the transient climate response: a tidal forcing experiment

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Acta Oceanologica Sinica 2020年第1期39卷 52-62页

作者： Yi Yu Hailong Liu Pengfei Lin Jian Lan Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 510275China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China College of Earth Sciences University of Chinese Academy of SciencesBeijing 100049China College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266003China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao266071China

In this study, the impact of oceanic processes on the sensitivity of transient climate change is investigated using two sets of coupled experiments with and without tidal forcing, which are termed ExpTide and ExpControl,respectively. After introducing tidal forcing, the transient climate response(TCR) decreases from 2.32 K to 1.90 K,and the surface air temperature warming at high latitudes decreases by 29%. Large ocean heat uptake efficiency and heat storage can explain the low TCR in ExpTide. Approximately 21% more heat is stored in the ocean in ExpTide(1.10×10^24 J) than in ExpControl(0.91×10^24 J). Most of the large ocean warming occurs in the upper 1 000 m between 60°S and 60°N, primarily in the atlantic and Southern Oceans. This ocean warming is closely related to the atlantic meridional overturning circulation(AMOC). The initial transport at mid-and high latitudes and the decline in the AMOC observed in ExpTide are both larger than those observed in ExpControl. The spatial structures of AMOC are also different with and without tidal forcing in present experiments. The AMOC in ExpTide has a large northward extension. We also investigated the relationship between AMOC and TCR suggested by previous studies using the present experiments.

关键词： tidal forcing transient climate response ocean heat uptake atlantic meridional overturning circulation

The impacts of different surface boundary conditions for sea surface salinity on simulation in an OGCM

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Atmospheric and Oceanic Science Letters 2016年第6期9卷 465-470页

作者： JIN Jiang-Bo ZENG Qing-Cun LIU Hai-Long WU Lin International Center for Climate and Environment Sciences(ICCES) Institute of Atmospheric Physics(IAP)Chinese Academy of Sciences(CAS) College of Earth Science University of Chinese Academy of Sciences State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of Sciences State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry(LAPC) Institute of Atmospheric PhysicsChinese Academy of Sciences

An OGCM, LICOM2.0, was used to investigate the effects of different surface boundary conditions for sea surface salinity （SSS） on simulations of global mean salinity, SSS, and the atlantic meridional overturning circulation （AMOC）. Four numerical experiments （CTRL, Expl, Exp2 and Exp3） were designed with the same forcing data-set, CORE.v2, and different surface boundary conditions for SSS~ A new surface salinity boundary condition that consists of both virtual and real salt fluxes was adopted in the fourth experiment （Exp3）. Compared with the other experiments, the new salinity boundary condition prohibited a monotonous increasing or decreasing global mean salinity trend. As a result, global salinity was approximately conserved in EXP3. In the default salinity boundary condition setting in LICOM2.0, a weak restoring salinity term plays an essential role in reducing the simulated SSS bias, tending to increase the global mean salinity. However, a strong restoring salinity term under the sea ice can reduce the global mean salinity. The authors also found that adopting simulated SSS in the virtual salt flux instead of constant reference salinity improved the simulation of AMOC, whose strength became closer to that observed.

关键词： Surface salinity boundarycondition real salt flux atlantic meridional overturning circulation global mean salinity