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Causes of Mid-Pliocene Strengthened Summer and Weakened Winter Monsoons over East Asia

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Advances in Atmospheric Sciences 2015年第7期32卷 1016-1026页

作者： ZHANG Ran JIANG Dabang ZHANG Zhongshi Climate Change research Center Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences Nansen–Zhu International research Centre Institute of Atmospheric PhysicsChinese Academy of Sciences Bjerknes Centre for Climate research Uni Research

The mid-Pliocene warm period was the most recent geological period in Earth＇s history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds （EASWs） strengthened in monsoonal China, and that East Asian winter winds （EAWWs） weakened in northern monsoonal China during this period, as compared to the pre-industrial period. However, the corresponding mechanisms are still unclear. In this paper, the results of a set of numerical simulations are reported to analyze the effects of changed boundary conditions on the mid-Pliocene East Asian monsoon climate, based on PRISM3 （Pliocene research Interpretation and Synoptic Mapping） palaeoenvironmental recon- struction. The model results showed that the combined changes of sea surface temperatures, atmospheric CO2 concentration, and ice sheet extent were necessary to generate an overall warm climate on a large scale, and that these factors exerted the greatest effects on the strengthening of EASWs in monsoonal China. The orographic change produced significant local warming and had the greatest effect on the weakening of EAWWs in northern monsoonal China in the mid-Pliocene. Thus, these two factors both had important but different effects on the monsoon change. In comparison, the effects of vegetational change on the strengthened EASWs and weakened EAWWs were relatively weak. The changed monsoon winds can be ex- plained by a reorganization of the meridional temperature gradient and zonal thermal contrast. Moreover, the effect of orbital parameters cannot be ignored. Results showed that changes in orbital parameters could have marked!y affected the EASWs and EAWWs, and caused significant short-term oscillations in the mid-Pliocene monsoon climate in East Asia.

关键词： mid-Pliocene East Asian monsoon orographic change orbital parameters

Impacts of Model Mismatch and Array Scale on Channel Estimation for XL-HRIS-Aided Systems

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ZTE Communications 2024年第1期22卷 24-33页

作者： LU Zhizheng HAN Yu JIN Shi National Mobile Communications research Laboratory Southeast Uni-versityNanjing 210096China

Extremely large-scale hybrid reconfigurable intelligence surface(XL-HRIS),an improved version of the RIS,can receive the incident signal and enhance communication ***,as the RIS size increases,the phase variations of the received signal across the whole array are nonnegligible in the near-field region,and the channel model mismatch,which will decrease the estimation accuracy,must be *** this paper,the lower bound(LB)of the estimated parameter is studied and the impacts of the distance and signal-tonoise ratio(SNR)on LB are then ***,the impacts of the array scale on LB and spectral efficiency(SE)are also *** results verify that even in extremely large-scale array systems with infinite SNR,channel model mismatch can still limit estimation ***,this impact decreases with increasing distance.

关键词： XL-HRIS near-field LB model mismatch parameter estimation

Mid-Pliocene Westerlies from Plio MIP Simulations

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Advances in Atmospheric Sciences 2015年第7期32卷 909-923页

作者： LI Xiangyu JIANG Dabang ZHANG Zhongshi ZHANG Ran TIAN Zhiping YAN Qing Nansen–Zhu International research Centre Institute of Atmospheric PhysicsChinese Academy of Sciences university of Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences Climate Change research Center Chinese Academy of Sciences uni research Bjerknes Centre for Climate Research

The midlatitude westerlies are one of the major components of the global atmospheric circulation. They play an important role in midlatitude weather and climate, and are particularly significant in interpreting aeolian sediments. In this study, we analyzed the behavior and the possible mechanism involved in the change of the westerlies, mainly in terms of the jet stream position, in the mid-Pliocene warm period （3.3 to 3.0 million years ago） using simulations of 15 climate models from the Pliocene Model Intercomparison Project （PlioMIP）. Compared to the reference period, the mid-Pliocene midlatitude westerlies generally shifted poleward （approximately 3.6° of latitude in the Northern Hemisphere and 1.9~ of latitude in the Southern Hemisphere at 850 hPa level） with a dipole pattern. The dipole pattern of the tropospheric zonal wind anomalies was closely related to the change of the tropospheric meridional temperature gradient as a result of thermal structure adjustment. The poleward shift of the midlatitude westerly jet corresponded to the poleward shift of the mean meridional circulation. The sea surface temperatures and sea ice may have affected the simulated temperature structure and zonal winds, causing the spread of the westerly anomalies in the mid-Pliocene between the atmosphere-only and coupled atmosphere-ocean general circulation model simulations.

关键词： mid-Pliocene westerly climate model PlioMIP

Greenland Ice Sheet Contribution to Future Global Sea Level Rise based on CMIP5 Models

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Advances in Atmospheric Sciences 2014年第1期31卷 8-16页

作者： YAN Qing WANG Huijun Ola M.JOHANNESSEN ZHANG Zhongshi Nansen-Zhu International research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Nansen Environmental and Remote Sensing Center university of the Chinese Academy of Sciences Climate Change research Center Chinese Academy of Sciences Nansen Scientific Society Bjerknes Centre for Climate research Uni Research

Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large uncertainties in modeled climate and ice sheet behavior. We used the ice sheet model SICOPOLIS （Simulation COde for POLythermal Ice Sheets） driven by climate projections from 20 models in the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to estimate the GrlS contribution to global SLR. Based on the outputs of the 20 models, it is estimated that the GrIS will contribute 0-16 （0-27） cm to global SLR by 2100 under the Representative Concentration Pathways （RCP） 4.5 （RCP 8.5） scenarios. The projected SLR increases further to 7-22 （7-33） cm with 2~basal sliding included. In response to the results of the multimodel ensemble mean, the ice sheet model projects a global SLR of 3 cm and 7 cm （10 cm and 13 cm with 2~basal sliding） under the RCP 4.5 and RCP 8.5 scenarios, respectively. In addition, our results suggest that the uncertainty in future sea level projection caused by the large spread in climate projections could be reduced with model-evaluation and the selective use of model outputs.

关键词： sea level rise Greenland ice sheet ice sheet modeling model evaluation

Arctic Sea Ice and Eurasian Climate:A Review

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Advances in Atmospheric Sciences 2015年第1期32卷 92-114页

作者： GAO Yongqi SUN Jianqi LI Fei HE Shengping Stein SANDVEN YAN Qing ZHANG Zhongshi Katja LOHMANN Noel KEENLYSIDE Tore FUREVIK SUO Lingling Nansen-Zhu International research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Nansen Environmental and Remote Sensing Center/Bjerknes Center for Climate research Climate Change research Center Chinese Academy of Sciences uni research/Bjerknes Center for Climate research Max-Planck Institute for Meteorology Geophysical Institute University of Bergen/Bjerknes Center for Climate Research

The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian ***, observational and modelling studies are covered to summarize several major themes, including： the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era,as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response（e.g., atmospheric circulation, air temperature） to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research.

关键词： Arctic sea ice Eurasian climate Arctic Oscillation review

Unprecedented Retreat in a 50-Year Observational Record for Petermann Glacier, North Greenland

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Atmospheric and Oceanic Science Letters 2013年第5期6卷 259-265页

作者： Ola M. JOHANNESSEN Mohamed BABIKER Martin W. MILES Nansen Environmental and Remote Sensing Center Nansen Scientific Society Nansen-Zhu International research Center Institute of Atmospheric Physics Chinese Academy of Sciences uni research as Bjerknes Centre for Climate research

Petermann Glacier is a marine-terminating outlet glacier that had a 70 km-long floating ice tongue prior to a ～ 270 km2 calving event that was observed from satellite sensors in August 2010,shortening the ice tongue by ～ 27 ***,in July 2012,another 10 km was lost through *** order to understand these events in perspective,here the authors perform a long-term data analysis of Petermann Glacier calving-front variability and ice velocity for each year in the 1990s-2000s,supplemented by available observations from the previous three *** major （on the order of 100 krm2） calving events are identified,with ～ 153 km2 calved from 1959 to 1961,～ 168 km2 in 1991,～ 71 km2 in 2001,～ 270 km2 in 2010,and ～ 130 km2 in 2012-as well as ～ 31 k m2 calved in *** increased frequency of major calving events in recent years has left the front terminus position retreated nearly 25 km beyond the range of observed in previous *** contrast,stable ice-dynamics are suggested from ice-velocity measurements made each year between 1993-2012,which are on average 1063 m yr-1,with limited interannual variability and no significant trend; moreover,there is no apparent relationship between ice-velocity variability and calving *** degree to which the massive calving events in 2010 and 2012 represent natural episodic variability or a response to atmospheric and/or oceanic changes remains speculative; however,melt-induced weakening of the floating ice tongue in recent years is strongly suggested.

关键词： Greenland outlet glaciers iceberg calving satellite remote sensing

The Effect of Non-equilibrium Condensation on the Drag Coefficient in a Transonic Airfoil Flow

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Journal of Thermal Science 2012年第6期21卷 518-524页

作者： I.W.Kim M.M.A.Alam S.J.Lee Y.D.Kwon S.B.Kwon School of Mechanical Engineering Kyungpook Nat.Uni.1370Sankyuk-dongDaegu 702-701Korea Dept.of Advanced & Control Eng.Saga uni.Japan

In this study, a transonic flow past NACA0012 profile at angle of attack α=0^0 whose aspect ratio AR is 1.0 with non-equilibrium condensation is analyzed by numerical analysis using a TVD scheme and is investigated using an intermittent indraft type supersonic wind tunnel. Transonic flows of 0.78-0.90 in free stream Mach number with the variations of the stagnation relative humidity（φ0） are tested. For the same free stream Mach number, the increase in φ0 causes decrease in the drag coefficient of profile which is composed of the drag components of form, viscous and wave. In the case of the same Moo and To, for more than φ0=30%, despite the irreversibility of process in non-equilibrium condensation, the drag by shock wave decreases considerably with the increase of φ0. On the other hand, it shows that the effect of condensation on the drag coefficients of form and viscous is negligible. As an example, the decreasing rate in the drag coefficient of profile caused by the influence of non-equilibrium condensation for the case of M∞=0.9 and φ0 =50% amounts to 34%. Also, it were turned out that the size of supersonic bubble （that is, the maximum height of supersonic zone） and the deviation of pressure coefficient from the value for M=1 decrease with the increase of φ0 for the same M∞.

关键词： Non-equilibrium condensation Transonic Moist air Drag coefficient Pressure coefficient

Potential impacts of enhanced tropical cyclone activity on the El Ni?o–Southern Oscillation and East Asian monsoon in the mid-Piacenzian warm period

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Atmospheric and Oceanic Science Letters 2019年第1期12卷 1-11页

作者： YAN Qing ZHANG Zhongshi ZHANG Ran Nansen-Zhu International research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Department of Atmospheric Science School of Environmental Studies China University of Geosciences Bjerknes Center for Climate research Uni Research Climate Climate Change research Center Chinese Academy of Sciences

Tropical cyclones(TCs)not only passively respond to climate change,but also play an important role in vertical mixing of the upper ocean and in driving oceanic heat *** a fully coupled climate model,the authors investigate the potential effect of TC-induced vertical mixing on the El Nino–Southern Oscillation(ENSO)and East Asian monsoon in the mid-Piacenzian,during which global TCs are estimated to have been *** experiments indicate that the TC-induced oceanic mixing over global storm basins leads to additional warming over the eastern tropical Pacific and a deeper thermocline in the mid-Piacenzian,whereas it dampens the interannual variability of *** the East Asian monsoon circulations,low-level(850 hPa)summer and winter winds are intensified in response to enhanced vertical mixing,with a southward/westward shift of the western North Pacific high and westerly jet in summer and a deepened East Asian trough in *** climatic features are largely reproduced in the experiment with enhanced vertical mixing only over the central-eastern North *** results may shed light on TC feedbacks associated with vertical mixing and advance our understanding on mid-Piacenzian climate.

关键词： Mid-Piacenzian climate modeling tropical cyclone ENSO

Stability of Macroscopic Binary Systems

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Communications in Theoretical Physics 2019年第11期71卷 1335-1340页

作者： G.G.Adamian N.V.Antonenko H.Lenske V.V.Sargsyan Joint Institu te for Nuclear research 141980 DubnaRussia Ins titut fur Theore tische Physik der Jus tus-Liebig—uni versit Nt D-35392 GiessenGermany

The Darwin instability effect in the binary systems(di-planets, di-stars, and di-galaxies) is analyzed within the model based on the Regge-like laws. All possible binary stars are found satisfying the Darwin instability condition that requires to search for other mechanism triggering the merger of the contact binary objects. New analytical formulas are obtained for the orbital rotation period and the relative distance between components of the binary system. The decreasing and increasing periods as functions of mass asymmetry are related, respectively, with the non-overlapping and overlapping stage of the binary object evolution.

关键词： Regge laws binary stars and galaxies Darwin instability effect