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Changes in the seasonal amplitude of northern ecosystem productivity under future global warming

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Atmospheric and Oceanic Science Letters 2023年第3期16卷 1-6页

作者： Jiawen ZHU Xiaofei Gao Xiaodong Zeng International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjingChina University of Chinese Academy of Sciences BeijingChina

观测显示过去几十年北半球大气二氧化碳季节幅度大幅增加,这主要是由北半球陆地净生态系统生产力季节幅度的增加所致。但是,因为气候变化和植被动态的不确定性,未来陆地净生态系统生产力季节幅度的变化还很不清楚.本工作利用全球植被动... 详细信息

观测显示过去几十年北半球大气二氧化碳季节幅度大幅增加,这主要是由北半球陆地净生态系统生产力季节幅度的增加所致。但是,因为气候变化和植被动态的不确定性,未来陆地净生态系统生产力季节幅度的变化还很不清楚.本工作利用全球植被动力学模式研究了全球变暖背景下北纬45°以北陆地净生态系统生产力季节幅度的变化.作者做了两大类试验:当代试验(1981-2000)和CMIP5RCP8.5变暖情景驱动的未来试验(2081-2100).结果显示,在RCP8.5变暖情景下北半球中高纬陆地净生态系统生产力季节幅度整体增加,这是因为陆地净生态系统生产力的月最大值增加且月最小值减小.最大(最小)陆地净生态系统生产力的增加(减小)是由于总初级生产力的增加强(弱)于生态系统总呼吸,总初级生产力和生态系统总呼吸的变化都主要受地表气温和植被动态的驱动.本工作强调了植被动态对北半球中高纬陆地生态系统碳循环的关键调制作用,也强调了在地球系统模式中包含全球植被动力学模式的重要性。

关键词：陆地生态系统碳循环全球变暖植被动态碳循环的季节变化

Changes in Global Vegetation Distribution and Carbon Fluxes in Response to Global Warming:Simulated Results from IAP-DGVM in CAS-ESM2

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Advances in Atmospheric Sciences 2022年第8期39卷 1285-1298,I0002-I0010页

作者： Xiaofei GAO Jiawen ZHU Xiaodong ZENG Minghua ZHANG Yongjiu DAI Duoying JI He ZHANG International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China School of Marine and Atmospheric Sciences Stony Brook UniversityNY 11790USA School of Atmospheric Sciences Sun Yat-Sen UniversityGuangzhou 510275China College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China

Terrestrial ecosystems are an important part of Earth systems,and they are undergoing remarkable changes in response to global warming.This study investigates the response of the terrestrial vegetation distribution and carbon fluxes to global warming by using the new dynamic global vegetation model in the second version of the Chinese Academy of Sciences(CAS)Earth System Model(CAS-ESM2).We conducted two sets of simulations,a present-day simulation and a future simulation,which were forced by the present-day climate during 1981-2000 and the future climate during 2081-2100,respectively,as derived from RCP8.5 outputs in CMIP5.CO_(2)concentration is kept constant in all simulations to isolate CO_(2)-fertilization effects.The results show an overall increase in vegetation coverage in response to global warming,which is the net result of the greening in the mid-high latitudes and the browning in the tropics.The results also show an enhancement in carbon fluxes in response to global warming,including gross primary productivity,net primary productivity,and autotrophic respiration.We found that the changes in vegetation coverage were significantly correlated with changes in surface air temperature,reflecting the dominant role of temperature,while the changes in carbon fluxes were caused by the combined effects of leaf area index,temperature,and precipitation.This study applies the CAS-ESM2 to investigate the response of terrestrial ecosystems to climate warming.Even though the interpretation of the results is limited by isolating CO_(2)-fertilization effects,this application is still beneficial for adding to our understanding of vegetation processes and to further improve upon model parameterizations.

关键词： global warming vegetation distribution carbon flux leaf area index surface air temperature

Development of an Establishment Scheme for a DGVM

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Advances in Atmospheric Sciences 2016年第7期33卷 829-840页

作者： Xiang SONG Xiaodong ZENG Jiawen ZHU Pu SHAO International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of lnformation Science&TechnologyNanjing 210044 University of Chinese Academy of Sciences Beijing 100049

Environmental changes are expected to shift the distribution and abundance of vegetation by determining seedling estab- lishment and success. However, most current ecosystem models only focus on the impacts of abiotic factors on biogeophysics （e.g., global distribution, etc.）, ignoring their roles in the population dynamics （e.g., seedling establishment rate, mortality rate, etc.） of ecological communities. Such neglect may lead to biases in ecosystem population dynamics （such as changes in population density for woody species in forest ecosystems） and characteristics. In the present study, a new establishment scheme for introducing soil water as a function rather than a threshold was developed and validated, using version 1.0 of the IAP-DGVM as a test bed. The results showed that soil water in the establishment scheme had a remarkable influence on forest transition zones. Compared with the original scheme, the new scheme significantly improved simulations of tree population density, especially in the peripheral areas of forests and transition zones. Consequently, biases in forest fractional coverage were reduced in approximately 78.8% of the global grid cells. The global simulated areas of tree, shrub, grass and bare soil performed better, where the relative biases were reduced from 34.3% to 4.8%, from 27.6% to 13.1%, from 55.2% to 9.2%, and from 37.6% to 3.6%, respectively. Furthermore, the new scheme had more reasonable dependencies of plant functional types （PFTs） on mean annual precipitation, and described the correct dominant PFTs in the tropical rainforest peripheral areas of the Amazon and central Africa.

关键词： establishment scheme soil water IAP-DGVM1.0 forest population density fractional coverage

CAS-ESM2.0 Successfully Reproduces Historical Atmospheric CO_(2) in a Coupled Carbon−Climate Simulation

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Advances in Atmospheric Sciences 2024年第4期41卷 572-580页

作者： Jiawen ZHU Juanxiong HE Duoying JI Yangchun LI He ZHANG Minghua ZHANG Xiaodong ZENG Kece FEI Jiangbo JIN International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjing 210044China College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China School of Marine and Atmospheric Sciences Stony Brook UniversityNY 11790USA University of Chinese Academy of Sciences Beijing 100049China

The atmospheric carbon dioxide(CO_(2))concentration has been increasing rapidly since the Industrial Revolution,which has led to unequivocal global warming and crucial environmental change.It is extremely important to investigate the interactions among atmospheric CO_(2),the physical climate system,and the carbon cycle of the underlying surface for a better understanding of the Earth system.Earth system models are widely used to investigate these interactions via coupled carbon-climate simulations.The Chinese Academy of Sciences Earth System Model version 2(CAS-ESM2.0)has successfully fixed a two-way coupling of atmospheric CO_(2)with the climate and carbon cycle on land and in the ocean.Using CAS-ESM2.0,we conducted a coupled carbon-climate simulation by following the CMIP6 proposal of a historical emissions-driven experiment.This paper examines the modeled CO_(2)by comparison with observed CO_(2)at the sites of Mauna Loa and Barrow,and the Greenhouse Gases Observing Satellite(GOSAT)CO_(2)product.The results showed that CAS-ESM2.0 agrees very well with observations in reproducing the increasing trend of annual CO_(2)during the period 1850-2014,and in capturing the seasonal cycle of CO_(2)at the two baseline sites,as well as over northern high latitudes.These agreements illustrate a good ability of CAS-ESM2.0 in simulating carbon-climate interactions,even though uncertainties remain in the processes involved.This paper reports an important stage of the development of CAS-ESM with the coupling of carbon and climate,which will provide significant scientific support for climate research and China’s goal of carbon neutrality.

关键词： CAS-ESM atmospheric CO_(2) coupled carbon-climate simulation emissions-driven CMIP6 experiment

Comprehensive Study on the Influence of Evapotranspiration and Albedo on Surface Temperature Related to Changes in the Leaf Area Index

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Advances in Atmospheric Sciences 2015年第7期32卷 935-942页

作者： zhu jiawen ZENG Xiaodong International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology

Many studies have investigated the influence of evapotranspiration and albedo and emphasize their separate effects but ignore their interactive influences by changing vegetation status in large amplitudes. This paper focuses on the comprehensive influence of evapotranspiration and albedo on surface temperature by changing the leaf area index （LAD between 30^-90~N. Two LAI datasets with seasonally different amplitudes of vegetation change between 30^-90~N were used in the simulations. Seasonal differences between the results of the simulations are compared, and the major findings are as follows. （1） The interactive effects of evapotranspiration and albedo on surface temperature were different over different regions during three seasons [March-April-May （MAM）, June-July-August （JJA）, and September-October-November （SON）], i.e., they were always the same over the southeastern United States during these three seasons but were opposite over most regions between 30°-90°N during JJA. （2） Either evapotranspiration or albedo tended to be dominant over different areas and during different seasons. For example, evapotranspiration dominated almost all regions between 30^-90~N during JJA, whereas albedo played a dominant role over northwestern Eurasia during MAM and over central Eurasia during SON. （3） The response of evapotranspiration and albedo to an increase in LAI with different ranges showed different paces and signals. With relatively small amplitudes of increased LAI, the rate of the relative increase in evapotranspiration was quick, and positive changes happened in albedo. But both relative changes in evapotranspiration and albedo tended to be gentle, and the ratio of negative changes of albedo increased with relatively large increased amplitudes of LAI.

关键词： surface temperature evapotranspiration albedo leaf area index comprehensive influence

Effects of Varying Copper Content on the Microstructure and Mechanical Properties of FeCoNiCu_(x)

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Journal of Wuhan University of Technology(Materials Science) 2022年第5期37卷 986-991页

作者：杨颜如 ZHANG Yichen LI jiawen 朱和国 College of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing210094China

Five sets of high entropy alloys(HEAs)FeCoNiCu_(x)(x=0.5,1.0,1.5,2.0,2.5)were produced by vacuum induction smelting.The effects of Cu content on the microstructure and mechanical properties of the alloys were interrogated by X-ray diffractometer(XRD),field scanning electron microscope(FESEM)and tensile mechanical test.The result shows that the HEAs form single FCC solid solution phase.With the increase of Cu content,the diffraction peak first deviated to the right and then shifted to the left.The alloys changed from equiaxed crystal structure to refined dendritic crystal structure,as Cu content increased.A large number of Cu atoms are isolated in the inter-crystalline region.The tensile mechanical tests show that with the increase of Cu content,the ultimate tensile strength first increased and then decreased.When x is 2.0,the ultimate tensile strength reaches a maximum of 473 MPa,the percent elongation is 43.0%,and the fracture presents ductile behaviour.

关键词： FeCoNiCu alloy copper content microstructure elemental segregation mechanical properties

Mass transfer mechanisms in fixed-bed adsorption of erythromycin

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Frontiers of Chemical Science and Engineering 2008年第4期2卷 353-360页

作者： Ying SUN Jiawen ZHU Kui CHEN Sheng zhu Jie XU Chemical Engineering Research Centre East China University of Science and TechnologyShanghai 200237China

The equilibrium and kinetic characteristics of the adsorption of erythromycin to Sepabeads SP825 were determined.The equilibrium data in a batch system was well described by a Langmuir isotherm.The separation performance was investigated in a fixed-bed system with respect to the adsorption superficial velocity,ionic strength and pH.A mathematical model was used to simulate the mass transfer mechanism,taking film mass transfer,pore diffusion and axial dispersion into account.The model predictions were consistent with the experi-mental data and were consequently used to determine the mass transfer coefficients.

关键词： fixed-bed adsorption superficial velocity ionic strength erythromycin However investigations on the parameters governing the performance of this technology are still scarce.In the present work a polymeric and porous resin Sepabeads SP825 resin was used for its higher adsorption efficiency compared with the resins reported.The equilib-rium capacity of Sepabeads SP825 for EM in a batch system was established using a Langmuir isotherm.The effects of superficial velocity ionic strength and pH on the adsorption process were determined from the results of fixed bed experiments.And a model of the purification process was used to simulate the mass transfer mechanism which has taken film mass transfer pore diffusion and axial dispersion into account.The experimental adsorp-tion measurements were compared to the results calcu-lated from the model.The completion of these studies provide some essential parameters which are required in order to design a successful purification process and better understand the fundamentals of these process.

Free-standing hybrid films comprising of ultra-dispersed titania nanocrystals and hierarchical conductive network for excellent high rate performance of lithium storage

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Nano Research 2021年第7期14卷 2301-2308页

作者： Kunlei zhu Chenyu Li Yushuang Jiao Jiawen ZHU Hongtao Ren Yufeng Luo Shoushan Fan Kai Liu College of Chemistry and Chemical Engineering Qufu Normal UniversityJingxuan West Road NO.57Qufu 273165China State Key Laboratory of New Ceramics and Fine Processing and Key Laboratory of Advanced Materials of Ministry of EducationSchool of Materials Science and EngineeringTsinghua UniversityBeijing 100084China School of Materials Science and Engineering Liaocheng UniversityHunan Road No.1Liaocheng 252000China Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center Tsinghua UniversityBeijing 100084China

The construction of advanced electrode materials is key to the field of energy storage.Herein,a free-standing anatase titania(TiO_(2))nanocrystal/carbon nanotube(CNT)film is reported using a simple and scalable sol-gel method,followed by calcination.This unique free-standing film comprises ultra-small TiO_(2) nanocrystals(~5.9 nm)and super-aligned CNTs,with ultra-dispersed TiO_(2) nanocrystals on the surfaces of the CNTs.On the one hand,these TiO_(2) nanocrystals can significantly decrease the diffusion distance of the charges and on the other hand,the cross-linked CNTs can act as a three-dimensional(3D)conductive network,allowing the fast transport of electrons.In addition,the film is free-standing,without requiring electrode fabrication and additional conductive agents and binders.Owing to these above synergistic effects,the film is directly used as an anode in Li-ion batteries,and delivers a high discharge capacity of~105 mAh·g^(−1) at high rate of 60 C(1 C=170 mA·g^(−1))and excellent cycling performance over 2,500 cycles at 30 C.These results indicate that the free-standing anatase TiO_(2) nanocrystal/CNT film affords a superior performance among the various TiO_(2) materials and can be a promising anode material for fast-charging Li-ion batteries.Moreover,the TiO_(2)/CNT film exhibits an areal capacity of up to 2.4 mAh·cm^(−2),confirming the possibility of its practical use.

关键词： carbon nanotubes free-standing high rate Li-ion batteries TiO_(2) ultra-small

The global regulation of c-di-GMP and cAMP in bacteria

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mLife 2024年第1期3卷 42-56页

作者： Cong Liu Rui Shi Marcus S.Jensen Jingrong zhu jiawen Liu Xiaobo Liu Di Sun Weijie Liu Jiangsu Key Laboratory of Phylogenomics&Comparative Genomics School of Life SciencesJiangsu Normal UniversityXuzhouChina Key Laboratory of Metabolic Engineering and Biosynthesis Technology Ministry of Industry and Information TechnologyNanjing University of Science and TechnologyNanjingChina

Nucleotide second messengers are highly versatile signaling molecules that regulate a variety of key biological processes in bacteria.The best-studied examples are cyclic AMP(cAMP)and bis-(3'-5')-cyclic dimeric guanosine monophosphate(c-di-GMP),which both act as global regulators.Global regulatory frameworks of c-di-GMP and cAMP in bacteria show several parallels but also significant variances.In this review,we llustrate the global regulatory models of the two nucleotide second messengers,compare the different regulatory frameworks between c-di-GMP and cAMP,and discuss the mechanisms and physiological significance of cross-regulation between c-di-GMP and cAMP.c-di-GMP responds to numerous signals de-pendent on a great number of metabolic enzymes,and it regulates various signal transduction pathways through its huge number of effectors with varying activities.In contrast,due to the limited quantity,the cAMP metabolic enzymes and its major effector are regulated at different levels by diverse signals.cAMP performs its global regulatory function primarily by controlling the transcription of a large number of genes via cAMP receptor protein(CRP)in most bacteria.This review can help us understand how bacteria use the two typical nucleotide second messengers to effectively coordinate and integrate various physiological processes,providing theoretical guidelines for future research.

关键词： bacteria cAMP c-di-GMP cross-regulation CRP