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Journal of Computational Mathematics 2020年第3期38卷 452-468页

作者： Jie Chen Zhengkang He Shuyu Sun Shimin Guo Zhangxin Chen School of Mathematics and Statistics Xi'an Jiaotong UniversityXi'an 710049China Computational transport phenomena laboratory Division of Physical Science and EngineeringKing Abdullah University of Science and TechnologyThuwal 23955-6900Kingdom of Saudi Arabia School of Mathematics and Statistics Xi'an Jiaotong Universityy Xi'an 710049China Department of Chemical&Petroleum Engineering Schulich School of EngineeringUniversity of Calgary2500 University Drive N.W.CalgaryAlberta T2N 1N4Canada

In this paper,we study linearly first and second order in time,uniquely solvable and unconditionally energy stable numerical schemes to approximate the phase field model of solid-state dewetting problems based on the novel"scalar auxiliary variable"(SAV)approach,a new developed efficient and accurate method for a large class of gradient *** schemes are based on the first order Euler method and the second order backward differential formulas(BDF2)for time discretization,and finite element methods for space *** proposed schemes are proved to be unconditionally stable and the discrete equations are uniquely solvable for all time *** numerical experiments are presented to validate the stability and accuracy of the proposed schemes.

关键词： phase field models Solid-state dewetting SAV Energy stability Surface diffusion Finite element method

Detecting Primary Precursors of January Surface Air Temperature Anomalies in China

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Journal of Meteorological Research 2017年第6期31卷 1096-1108页

作者： Guirong TAN Hong-Li REN Haishan CHEN Qinglong YOU Key laboratory of Meteorological Disaster of Ministry of Education/Joint International Research laboratory of Climate and Environment change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science &Technology laboratory for Climate Studies/CMA–NJU Joint laboratory for Climate Prediction Studies National Climate CenterChina Meteorological Administration Department of Atmospheric Science School of Environmental Studies China University of Geoscience

This study aims to detect the primary precursors and impact mechanisms for January surface temperature anomaly （JSTA） events in China against the background of global warming, by comparing the causes of two extreme JSTA events occurring in 2008 and 2011 with the common mechanisms inferred from all typical episodes during 1979- 2008. The results show that these two extreme events exhibit atmospheric circulation patterns in the mid-high latitudes of Eurasia, with a positive anomaly center over the Ural Mountains and a negative one to the south of Lake Baikal （UMLB）, which is a pattern quite similar to that for all the typical events. However, the Eurasian teleconnection patterns in the 2011 event, which are accompanied by a negative phase of the North Atlantic Oscillation, are different to those of the typical events and the 2008 event. We further find that a common anomalous signal appearing in early summer over the tropical Indian Ocean may be responsible for the following late-winter Eurasian teleeonnec- lions and the associated JSTA events in China. We show that sea surface temperature anomalies （SSTAs） in the preceding summer over the western Indian Ocean （WIO） are intimately related to the UMLB-like circulation pattern in the following January. Positive WIOSSTAs in early summer tend to induce strong UMLB-like circulation anomalies in January, which may result in anomalously or extremely cold events in China, which can also be successfully reproduced in model experiments. Our results suggest that the WIOSSTAs may be a useful precursor for predicting JSTA events in China.

关键词： Eurasian teleconnection anomalous temperature in China seasonal climate prediction SST anomaly western Indian Ocean model experiment

Comparison of Controlling Parameters for Near-Equatorial Tropical Cyclone Formation between Western North Pacific and North Atlantic

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Journal of Meteorological Research 2021年第4期35卷 623-634页

作者： Changhao LU Xuyang GE Melinda PENG Key laboratory of Meteorological Disaster of Ministry of Education/Joint International Research laboratory of Climate and Environment change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China University of Colorado Colorado SpringColorado 80918USA

In this study,the differences in spatial distribution and controlling parameters for the formation of near-equatorial tropical cyclones(NETCs)between the western North Pacific(WNP)and the North Atlantic(NA)are *** exhibit distinctive spatial variabilities in different *** the past few decades,the majority of NETCs took place in WNP while none was observed in *** mechanism behind such a distinguishing spatial distribution difference is analyzed by using statistical *** is noted that the dynamical variables such as low-level relative vorticity and vertical wind shear(VWS)are likely the primary controlling *** with NA,larger low-level vorticity and smaller VWS appear over *** increase of vorticity attributes a lot to the turning of northeast trade *** in WNP tend to occur in the areas with VWS less than 9 m s^(-1),while the VWS in NA generally exceeds 10 m s^(-1).On the other hand,the sea surface temperature in the near-equatorial region of both of the two oceans exceeds 26.5℃and the difference of mid-level moisture is not significant;thus,thermal factors have little contribution to the distinction of NETC activities between WNP and *** oscillation(ISO)and synoptic-scale disturbances in WNP are also shown to be more favorable for NETC *** NETCs were generated in ISO active ***-scale disturbances in WNP obtain more energy from the mean flows through the barotropic energy conversion *** overall unfavorable thermal and dynamic conditions lead to the absence of NETCs in NA.

关键词： near-equatorial tropical cyclone(NETC) cyclogenesis genesis potential index(GPI)

Parallel Comparison of the 1982/83,1997/98 and 2015/16 Super El Nios and Their Effects on the Extratropical Stratosphere

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Advances in Atmospheric Sciences 2017年第9期34卷 1121-1133页

作者： Jian RAO Rongcai REN Key laboratory of Meteorological Disaster Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and Technology State Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

This study uses multiple sea surface temperature （SST） datasets to perform a parallel comparison of three super El Nifios and their effects on the stratosphere. The results show that, different from ordinary El Nifios, warm SST anomalies appear earliest in the western tropical Pacific and precede the super El Nifio peak by more than 18 months. In the previous winter, relative to the mature phase of El Nifio, as a precursor, North Pacific Oscillation-like circulation anomalies are observed. A Pacific-North America （PNA） teleconnection appears in the extratropical troposphere during the mature phase, in spite of the subtle differences between the intensities, as well as the zonal position, of the PNA lobes. Related to the negative rainfall response over the tropical Indian Ocean, the PNA teleconnection in the winter of 1997/98 is the strongest among the three super El Nifios. The northern winter stratosphere shows large anomalies in the polar cap temperature and the circumpolar westerly, if the interferences from other factors are linearly filtered from the circulation data. Associated with the positive PNA response in a super El Nino winter, positive polar cap temperature anomalies and circumpolar easterly anomalies, though different in timing, are also observed in the mature winters of the three super El Nifios. The stratospheric polar vortex in the next winter relative to the 1982/83 and 1997/98 events is also anomalously weaker and warmer, and the stratospheric circulation conditions remain to be seen in the coming winter following the mature phase of the 2015/16 event.

关键词： super El Nifio Pacific-North America (PNA) teleconnection stratosphere proceeding winter

Determination of the Backward Predictability Limit and Its Relationship with the Forward Predictability Limit

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Advances in Atmospheric Sciences 2019年第6期36卷 669-677页

作者： Xuan LI Ruiqiang DING Jianping LI State Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology College of Global change and Earth System Sciences (GCESS) Beijing Normal University

In this work, two types of predictability are proposed—forward and backward predictability—and then applied in the nonlinear local Lyapunov exponent approach to the Lorenz63 and Lorenz96 models to quantitatively estimate the local forward and backward predictability limits of states in phase space. The forward predictability mainly focuses on the forward evolution of initial errors superposed on the initial state over time, while the backward predictability is mainly concerned with when the given state can be predicted before this state happens. From the results, there is a negative correlation between the local forward and backward predictability limits. That is, the forward predictability limits are higher when the backward predictability limits are lower, and vice versa. We also find that the sum of forward and backward predictability limits of each state tends to fluctuate around the average value of sums of the forward and backward predictability limits of sufficient ***, the average value is constant when the states are sufficient. For different chaotic systems, the average value is dependent on the chaotic systems and more complex chaotic systems get a lower average value. For a single chaotic system,the average value depends on the magnitude of initial perturbations. The average values decrease as the magnitudes of initial perturbations increase.

关键词： nonlinear local Lyapunov exponent forward and backward predictability limit negative correlation average value

Effects of the Soil Heat Flux Estimates on Surface Energy Balance Closure over a Semi-Arid Grassland

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Acta meteorologica Sinica 2011年第6期25卷 774-782页

作者：岳平张强牛生杰成华王西育 Key laboratory of Arid Climatic change and Disaster Reduction of Gansu Province Institute of Arid MeteorologyChina Meteorological Administration Zhangye National Climatological Observatory Nanjing University of Information Science & Technology

Soil heat flux is important for surface energy balance （SEB）, and inaccurate estimation of soil heat flux often leads to surface energy imbalance. In this paper, by using observations of surface radiation fluxes and soil temperature gradients at a semi-arid grassland in Xilingguole, Inner Mongolia, China from June to September 2008, the characters of the SEB for the semi-arid grassland were analyzed. Firstly, monthly averaged diurnal variations of SEB components were revealed. A 30-min forward phase displacement of soil heat flux （G） observed by a fluxplate at the depth of 5-em below the soil surface was conducted and its effect on the SEB was studied. Secondly, the surface soil heat flux （Gs） was computed by using harmonic analysis and the effect of the soil heat storage between the surface and the fluxplate on the SEB was examined. The results show that with the 30-min forward phase displacement of observed G, the slope of the ordinary linear regression （OLR） of turbulent fluxes （H＋LE） against available energy （Rn G） increased from 0.835 to 0.842, i.e., the closure ratio of SEB increased by 0.7%, yet energy imclosure of 15.8% still existed in the SEB. When Gs, instead of G was used in the SEB equation, the slope of corresponding OLR of （H＋LE） against （Rn-Gs） reached 0.979, thereby the imelosure ratio of SEB was reduced to only 2.1%.

关键词： soil heat flux surface energy balance harmonic analysis turbulent fluxes available energy

Multidecadal Trends in Large-Scale Annual Mean SATa Based on CMIP5 Historical Simulations and Future Projections

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Engineering 2017年第1期3卷 136-143页

作者： Nan Xing Jianping Li Lanning Wang College of Global change and Earth System Science Beijing Normal University Belting 100875 China Belting Meteorological Observatory Belting 100089 China Joint Center for Global change Studies Beijing 100875 China

Based on observations and Coupled Model lntercomparison Project phase 5 （CMIP5） results, multidecadal variations and trends in annual mean surface air temperature anomalies （SATa） at global, hemispheric, and hemispheric land and ocean scales in the past and under the future scenarios of two representative concentration pathways （RCPs） are analyzed. Fifteen models are selected based on their performances in capturing the temporal variability, long-term trend, multidecadal variations, and trends in global annual mean SATa. Observational data analysis shows that the multidecadal variations in annual mean SATa of the land and ocean in the northern hemisphere （NH） and of the ocean in the southern hemisphere （SH） are similar to those of the global mean, showing an increase during the 1900-1944 and 1971-2000 periods, and flattening or even cooling during the 1945-1970 and 2001-2013 periods. These observed characteristics are basically reproduced by the models. However, SATa over SH land show an increase during the 1945-1970 period, which differs from the other hemispheric scales, and this feature is not captured well by the models. For the recent hiatus period （2001-2013）, the projected trends of BCC-CSM1-1-m, CMCC-CM, GFDL-ESM2M, and NorESM1-ME at the global and hemispheric scales are closest to the observations based on RCP4.5 and RCP8.5 scenarios, suggesting that these four models have better projection capability in SATa. Because these four models are better at simulating and projecting the multidecadal trends of SATa, they are selected to analyze future SATa variations at the global and hemispheric scales during the 2006-2099 period. The selected multi-model ensemble （MME） projected trends in annual mean SATa for the globe, NH, and SH under RCP4.5 （RCP8.5） are 0.17 （0.29） ℃, 0.22 （0.36） ℃, and 0.11 （0.23） ℃-decade-1 in the 21st century, respectively. These values are significantly lower than the projections of CMIP5 MME without model selection.

关键词： Surface air temperature anomalies (SATa) Multidecadal trend Coupled Model lntercomparison Project phase 5 (CMIPS) Projection

Stability-driven Structure Evolution:Exploring the Intrinsic Similarity Between Gas-Solid and Gas-Liquid Systems

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Chinese Journal of Chemical Engineering 2012年第1期20卷 167-177页

作者：陈建华杨宁葛蔚李静海 State Key laboratory of Multi-phase Complex Systems Institute of Process EngineeringChinese Academy of Sciences Graduate University of Chinese Academy of Sciences

As the core of the Energy-Minimization Multi-Scale(EMMS) approach,the so-called stability condi-tion has been proposed to reflect the compromise between different dominant mechanisms and believed to be in-dispensable for understanding the complex nature of gas-solid fluidization *** approach was recently ex-tended to the study of gas-liquid bubble *** this article,we try to analyze the intrinsic similarity between gas-solid and gas-liquid systems by using the EMMS ***,the model solution spaces for the two systems are depicted through a unified numerical solution strategy,so that we are able to find three structural hierarchies in the EMMS model for gas-solid *** may help to understand the roles of cluster diameter correlation and stability ***,a common characteristic of gas-solid and gas-liquid systems can be found by comparing the model solutions for the two systems,albeit structural parameters and stability criteria are specific in each system:two local minima of the micro-scale energy dissipation emerges simultaneously in the solution space of structure parameters,reflecting the compromise of two different dominant *** may share an equal value at a critical condition of operating conditions,and the global minimum may shift from one to the other when the oper-ating condition *** a result,structure parameters such as voidage or gas hold-up exhibit a jump change due to this shift,leading to dramatic structure variation and hence regime transition of these *** demonstrates that it is the stability condition that drives the structure variation and system evolution,which may be the intrinsic similarity of gas-solid and gas-liquid systems.

关键词： naulti-scale fluidize-d bed bubble column regime transition stability condition

INTERANNUAL VARIABILITY OF WINTER-TO-SPRING CIRCULATION TRANSITION OVER SOUTHERN CHINA AND ITS SURROUNDING AREAS AND MECHANISMS

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Journal of Tropical Meteorology 2019年第4期25卷 471-482页

作者： ZHOU Ming-sen JIAN Mao-qiu Center for Monsoon and Environment Research/Guangdong Province Key laboratory for Climate change and Natural Disaster Studies/School of Atmospheric Sciences Sun Yat-sen UniversityGuangzhou 510275 China Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519082China

The climatological features and interannual variation of winter-to-spring transition over southern China and its surrounding areas, and its possible mechanisms are examined in this study. The climatological mean winter-to-spring transition is approximately in mid-March over southern China and the northern South China Sea. During the transition stage, anomalous southwest winds prevail at low-level over southern China and its nearby regions with enhanced convergence center over southern China, bringing more moisture from the Bay of Bengal(BOB) and the South China Sea(SCS) to southern China;meanwhile, the upper level is characterized by an obvious divergence wind pattern over southern China to the southwest part of Japan and enhanced upward motion. All the change of circulation is favorable to an increase of precipitation over southern China after seasonal transition. The winter-to-spring transition is predominantly on the interannual variation over southern China and the northern SCS. Early winter-to-spring transitions may induce more precipitation over southern China in spring, especially in March, while late cases will result in less precipitation. The interannual variability of the winter-to-spring transition and the related large-scale circulation are closely associated with the decaying phase of ENSO events. The warm ENSO events contribute to early winter-to-spring transitions and more precipitation over southern China.

关键词： winter-to-spring transition southern China and its surrounding areas interannual variability mechanism ENSO

A PRINCIPAL MODE OF CIRCULATION COVARIATION BETWEEN THE NORTHERN AND SOUTHERN HEMISPHERES AND ITS ASSOCIATION WITH ENSO DURING BOREAL WINTER

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Journal of Tropical Meteorology 2017年第4期23卷 450-461页

作者：唐卫亚管兆勇钱代丽 Key laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint Intemational Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044 China

By employing the singular value decomposition(SVD) analysis, we have investigated in the present paper the covariations between circulation changes in the Northern(NH) and Southern Hemispheres(SH) and their associations with ENSO by using the NCEP/NCAR reanalysis, the reconstructed monthly NOAA SST, and CMAP precipitation along with NOAA Climate Prediction Center(CPC) ENSO indices. A bi-hemispheric covariation mode(hereafter BHCM) is explored, which is well represented by the first mode of the SVD analysis of sea surface pressure anomaly(SLPA-SVD1). This SVD mode can explain 57.36% of the total covariance of SLPA. BHCM varies in time with a long-term trend and periodicities of 3—5 years. The long term trend revealed by SVD1 shows that the SLP increases in the equatorial central and eastern Pacific but decreases in the western Pacific and tropical Indian Ocean, which facilitates easterlies in the lower troposphere to be intensified and El Ni觡o events to occur with lower frequency. The spatial pattern of the BHCM looks roughly symmetric about the equator in the tropics, whereas it is characterized by zonal disturbances in the mid-latitude of NH and is highly associated with AAO in the mid-latitude of SH. On inter-annual time scales, the BHCM is highly correlated with ENSO. The atmosphere in both the NH and SH responds to sea surface temperature anomalies in the equatorial region, while the contemporaneous circulation changes in the NH and SH in turn affect the occurrence of El Ni觡o/La Ni觡a. In boreal winter, significant temperature and precipitation anomalies associated with the BHCM are found worldwide. Specifically, in the positive phase of the BHCM,temperature and precipitation are anomalously low in eastern China and some other regions of East Asia. These results are helpful for us to better understand interactions between circulations in the NH and SH and the dynamical mechanisms behind these interactions.

关键词： Northern and Southern Hemispheres circulation variations covariation mode climate anomaly ENSO