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The Role of the Aerosol Indirect Effect in the Northern Indian Ocean Warming Simulated by CMIP5 Models

Atmospheric and Oceanic Science Letters 2014年第5期7卷 411-416页

作者： HU Ning LI Li-Juan WANG Bin State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Ministry of Education Key Laboratory for Earth System Modeling Center for Earth System Science Tsinghua University

The northern Indian Ocean （NIO） experienced a decadal-scale persistent warming from 1950 to 2000, which has influenced both regional and global climate. Because the NIO is a region susceptible to aerosols emis- sion changes, and there are still large uncertainties in the representation of the aerosol indirect effect （ALE） in CMIP5 （Coupled Model Intercomparison Project Phase 5） models, it is necessary to investigate the role of the AIE in the NIO warming simulated by these models. In this study, the authors select seven CMIP5 models with both the aerosol direct and indirect effects to investigate their performance in simulating the basin-wide decadal-scale NIO warming. The results show that the decreasing trend of the downwelling shortwave flux （FSDS） at the surface has the major damping effect on the SST increasing trend, which counteracts the warming effect of greenhouse gases （GHGs）. The FSDS decreasing trend is mostly contrib- uted by the decreasing trend of cloudy-sky surface downwelling shortwave flux （FSDSCL）, a metric used to measure the strength of the AIE, and partly by the clear-sky surface downwelling shortwave flux （FSDSC）. Models with a relatively weaker AIE can simulate well the SST increasing trend, as compared to observation. In contrast, models with a relatively stronger AIE produce a much smaller magnitude of the increasing trend, indicat- ing that the strength of the AIE in these models may be overestimated in the NIO.

关键词： Indian Ocean warming aerosol indirect ef-fect CMIP5

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Experimental deformation of shales at elevated temperature and pressure:Pore-crack system evolution and its effects on shale gas reservoirs

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Petroleum Science 2024年第6期21卷 3754-3773页

作者： Yi-Wen Ju Xin-Gao Hou Kui Han Yu Song Lei Xiao Cheng Huang Hong-Jian Zhu Li-Ru Tao Key Laboratory of Earth System Numerical Modeling and Application College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesChinese Academy of SciencesBeijing100049China Key Laboratory of Earth Exploration and Information Technique Ministry of EducationCollege of GeophysicsChengdu University of TechnologyChengdu610059SichuanChina Key Laboratory of Coalbed Methane Resource&Reservoir Formation Process Ministry of EducationSchool of Resources&Earth ScienceChina University of Mining and TechnologyXuzhou221116JiangsuChina

Although many studies based on naturally deformed samples have been carried out to investigate the pore-crack characteristics of shales,studies based on high temperature(T)and high pressure(P)deformation experiments,which can exclude sample heterogeneity factors,simulate deep T-P conditions,and generate a continuous deformation sequence,are still *** this study,shales with different deformation levels are generated by triaxial compression experiments,and methods including scanning electron microscopy,mercury injection,and gas sorption are utilized to characterize their influence factors and pore-crack *** indicate that T is the primary factor influencing shale deformation when P is low,while P is dominant under high P *** T<90℃ and P<60 MPa,shales undergo brittle deformation and their macropores decrease due to the compaction of primary pores,while mesopores increase because of the interconnection of *** 90℃200℃ and P>110 MPa,shales are subjected to ductile deformation,and their micro-and mesopores drop significantly due to the intense compaction in the matrix while macropores continuously increase with crack *** permeability of shale increases with the degree of deformation and ductile material contents are predicted to be a key factor determining whether open microcracks can be preserved after ductile *** account for these experimental results,an ideal model of micro pore-crack system evolution in deformed shales is further proposed,which can provide guidance for the exploration of shale gas resources in the deep or structurally complex zones.

关键词： Shale Deformation experiment Microscopic structure Pore-crack system Shale gas reservoir

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Constrained future brightening of solar radiation and its implication for China's solar power

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National Science Review 2023年第1期10卷 154-165页

作者： Yanyi He Kun Yang Martin Wild Kaicun Wang Dan Tong Changkun Shao Tianjun Zhou Department of Earth System Science Ministry of Education Key Laboratory for Earth System Modeling Institute for Global Change Studies Tsinghua University National Tibetan Plateau Data Center State Key Laboratory of Tibetan Plateau Earth System and Resource Environment Institute of Tibetan Plateau Research Chinese Academy of Sciences Institute for Atmospheric and Climate Science ETH Zürich Sino-French Institute for Earth System Science College of Urban and Environmental Sciences Peking University State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

As earth's primary energy source,surface downward solar radiation（Rs） determines the solar power potential and usage for climate change *** projections of Rsbased on climate models have large uncertainties that interfere with the efficient deployment of solar energy to achieve China' s carbon-neutrality *** we assess 24 models in the latest Coupled Model Inter comparison Project Phase 6 with historical observations in China and find systematic biases in simulating historical Rsvalues likely due to model biases in cloud cover and clear-sky radiation,resulting in largely uncertain projections for future changes in Based on emergent constraints,we obtain credible Rswith narrowed uncertainties by ～56% in the mid-twenty-first century and show that the mean Rschange during 2050-2069 relative to 1995-2014 is 30% more brightening than the raw *** in North China and Southeast China with higher power demand,the constrained projections present more significant brightening,highlighting the importance of considering the spatial changes in future Rswhen locating new solar energy infrastructures.

关键词： surface downward solar radiation CMIP6 model emergent constraint future change solar energy

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Non-negative matrix factorization based unmixing for principal component transformed hyperspectral data

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Frontiers of Information Technology & Electronic Engineering 2016年第5期17卷 403-412页

作者： Xiu-rui GENG Lu-yan JI Kang SUN Key Laboratory of Technology in Geo-spatial Information Processing and Application System Institute of Electronics Chinese Academy of Sciences Beijing 100190 China MOE Key Laboratory for Earth System Modeling Center for Earth System Science Tsinghua University Beijing 100084 China The 54th Research Institute of China Electronics Technology Group Corporation Shijiazhuang 050000 China

Non-negative matrix factorization(NMF) has been widely used in mixture analysis for hyperspectral remote sensing. When used for spectral unmixing analysis, however, it has two main shortcomings:(1) since the dimensionality of hyperspectral data is usually very large, NMF tends to suffer from large computational complexity for the popular multiplicative iteration rule;(2) NMF is sensitive to noise(outliers), and thus the corrupted data will make the results of NMF meaningless. Although principal component analysis(PCA) can be used to mitigate these two problems, the transformed data will contain negative numbers, hindering the direct use of the multiplicative iteration rule of NMF. In this paper, we analyze the impact of PCA on NMF, and find that multiplicative NMF can also be applicable to data after principal component transformation. Based on this conclusion, we present a method to perform NMF in the principal component space, named ‘principal component NMF'(PCNMF). Experimental results show that PCNMF is both accurate and time-saving.

关键词： Non-negative matrix factorization(NMF) Principal component analysis(PCA) Endmember Hyperspectral

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Evaluation of the Historical Sampling Error for Global Models

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Atmospheric and Oceanic Science Letters 2015年第5期8卷 250-256页

作者： SHEN Si LIU Juan-Juan WANG Bin State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences Ministry of Education Key Laboratory for Earth System Modeling Center of Earth System Science (CESS) Tsinghua University

Various ensemble-based schemes are employed in data assimilation because they can use the ensemble to estimate the flow-dependent background error covariance. The most common way to generate the real-time ensemble is to use an ensemble forecast; however, this is very time-consuming. The historical sampling approach is an alternative way to generate the ensemble,by picking some snapshots from historical forecast *** this approach, many ensemble-based assimilation schemes can be used in a deterministic forecast environment. Furthermore, considering the time that it saves, the method has the potential for operational ***, the historical sampling approach carries with it a special kind of sampling error because, in a historical forecast, the way to integrate the ensemble members is different from the way to integrate the initial conditions at the analysis time(i.e., forcing and lateral boundary condition differences, and ‘warm start' or ‘cold start' differences). This study analyzes the results of an experiment with the Global Regional Assimilation Prediction system-Global Forecast system(GRAPES-GFS), to evaluate how the different integration configurations influence the historical sampling error for global models. The results show that the sampling error is dominated by diurnal cycle patterns as a result of the radiance forcing *** the RMSEs of the sampling error are small, in view of the correlation coefficients of the perturbed ensemble, the sampling error for some variables on some levels(e.g., low-level temperature and humidity, stratospheric temperature and geopotential height and humidity), is non-negligible. The results suggest some caution must be applied, and advice taken, when using the historical sampling approach.

关键词： ensemble-based data assimilation historical sampli

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An Extension of the Dimension-Reduced Projection 4DVar

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Atmospheric and Oceanic Science Letters 2014年第4期7卷 324-329页

This paper extends the dimension-reduced projection four-dimensional variational assimilation method(DRP-4DVar) by adding a nonlinear correction process,thereby forming the DRP-4DVar with a nonlinear correction, which shall hereafter be referred to as the NC-DRP-4DVar. A preliminary test is conducted using the Lorenz-96 model in one single-window experiment and several multiple-window experiments. The results of the single-window experiment show that compared with the adjoint-based traditional 4DVar, the final convergence of the cost function for the NC-DRP-4DVar is almost the same as that using the traditional 4DVar, but with much less computation. Furthermore, the 30-window assimilation experiments demonstrate that the NC-DRP-4DVar can alleviate the linearity approximation error and reduce the root mean square error significantly.

关键词： data assimilation linear approximation nonlinear correction OSSE

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A New Approach to Implement Sigma Coordinate in a numerical Model

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Communications in Computational Physics 2012年第9期12卷 1033-1050页

作者： Yiyuan Li Donghai Wang Bin Wang State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijingChina Ministry of Education Key Laboratory for Earth System Modeling and Center for Earth System ScienceTsinghua UniversityBeijingChina

This study shows a new way to implement terrain-following s-coordinate in a numerical model,which does not lead to the well-known"pressure gradient force(PGF)"***,the causes of the PGF problemare analyzedwith existing methods that are categorized into two different types based on the ***,the new method that bypasses the PGF problem all together is *** comparing these threemethods and analyzing the expression of the scalar gradient in a curvilinear coordinate system,this study finds out that only when using the covariant scalar equations of s-coordinate will the PGF computational form have one term in each momentum component equation,thereby avoiding the PGF problem completely.A convenient way of implementing the covariant scalar equations of s-coordinate in a numerical atmospheric model is illustrated,which is to set corresponding parameters in the scalar equations of the Cartesian ***,two idealized experimentsmanifest that the PGF calculated with the new method is more accurate than using the classic *** method can be used for oceanic models as well,and needs to be tested in both the atmospheric and oceanic models.

关键词： Pressure gradient force(PGF) terrain-following sigma coordinate non-orthogonal basis vectors numerical modeling computational errors

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Simulation of Salinity Variability and the Related Freshwater Flux Forcing in the Tropical Pacific: An Evaluation Using the Beijing Normal University earth system Model(BNU-ESM)

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Advances in Atmospheric Sciences 2015年第11期32卷 1551-1564页

作者： ZHI Hai ZHANG Rong-Hua LIN Pengfei WANG Lanning The Earth System Modeling Center and College of Atmospheric Sciences Nanjing University of Information Science and Technology Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of Sciences State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences College of Global Change and Earth System Science Beijing Normal University

The climatology and interannual variability of sea surface salinity （SSS） and freshwater flux （FWF） in the equatorial Pacific are analyzed and evaluated using simulations from the Beijing Normal University earth system Model （BNU-ESM）. The simulated annual climatology and interannual variations of SSS, FWF, mixed layer depth （MLD）, and buoyancy flux agree with those observed in the equatorial Pacific. The relationships among the interannual anomaly fields simulated by BNU-ESM are analyzed to illustrate the climate feedbacks induced by FWF in the tropical Pacific. The largest interannual variations of SSS and FWF are located in the western-central equatorial Pacific. A positive FWF feedback effect on sea surface temperature （SST） in the equatorial Pacific is identified. As a response to El Nino-Southern Oscillation （ENSO）, the interannual variation of FWF induces ocean processes which, in turn, enhance ENSO. During El Nino, a positive FWF anomaly in the western-central Pacific （an indication of increased precipitation rates） acts to enhance a negative salinity anomaly and a negative surface ocean density anomaly, leading to stable stratification in the upper ocean. Hence, the vertical mixing and entrainment of subsurface water into the mixed layer are reduced, and the associated E1 Nino is enhanced. Related to this positive feedback, the simulated FWF bias is clearly reflected in SSS and SST simulations, with a positive FWF perturbation into the ocean corresponding to a low SSS and a small surface ocean density in the western-central equatorial Pacific warm pool.

关键词： freshwater flux salinity feedback tropical Pacific BNU-ESM

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Quantitative Analysis of the Feedback Induced by the Freshwater Flux in the Tropical Pacific Using CMIP5

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Advances in Atmospheric Sciences 2015年第10期32卷 1341-1353页

Freshwater flux （FWF） directly affects sea surface salinity （SSS） and hence modulates sea surface temperature （SST） in the tropical Pacific. This paper quantifies a positive correlation between FWF and SST using observations and simulations of the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to analyze the interannual variability in the tropical Pacific. Comparisons among the displacements of FWF, SSS and SST interannual variabilities illustrate that a large FWF variability is located in the west-central equatorial Pacific, covarying with a large SSS variability, whereas a large SST variability is located in the eastern equatorial Pacific. Most CMIP5 models can reproduce the fact that FWF leads to positive feedback to SST through an SSS anomaly as observed. However, the difference in each model＇s performance results from different simulation capabilities of the CMIP5 models in the magnitudes and positions of the interannual variabilities, including the mixed layer depth and the buoyancy flux in the equatorial Pacific. SSS anomalies simulated from the CMIP5 multi-model are sensitive to FWF interannual anomalies, which can lead to differences in feedback to interannual SST variabilities. The relationships among the FWF, SSS and SST interannual variabilities can be derived using linear quantitative measures from observations and the CMIP5 multi-model simulations. A 1 mm d-1 FWF anomaly corresponds to an SSS anomaly of nearly 0.12 psu in the western tropical Pacific and a 0.11℃ SST anomaly in the eastern tropical Pacific.

关键词： feedback freshwater flux CMIP5 correlation

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Comparisons of Soil Moisture Datasets over the Tibetan Plateau and application to the Simulation of Asia Summer Monsoon Onset

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Advances in Atmospheric Sciences 2010年第2期27卷 303-314页

作者：包庆刘屹岷施建成吴国雄 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Institute for Computational Earth System Science University of California

The influence of soil moisture on Asian monsoon simulation/prediction was less studied, partly due to a lack of available and reliable soil moisture datasets. In this study, we firstly compare several soil moisture datasets over the Tibetan Plateau, and find that the remote sensing products from the Advanced Microwave Scanning Radiometer for earth Observing system （AMSR-E） can capture realistic temporal variations of soil moisture better than the two reanalyses （NCEP and ECMWF） during the pre-monsoon seasons. Using the AMSR-E soil moisture product, we investigate the impacts of soil moisture over the Tibetan Plateau on Asian summer monsoon onset based on a Spectral Atmospheric Model developed at IAP/LASG （SAMIL）. Comparison between results with and without the assimilation of remotely sensed soil moisture data demonstrates that with soil moisture assimilated into SAMIL, the land-sea thermal contrast during pre-monsoon seasons is more realistic. Accordingly, the simulation of summer monsoon onset dates over both the Bay of Bengal and South China Sea regions are more accurate with AMSR-E soil moisture assimilated. This study reveals that the application of the soil moisture remote sensing products in a numerical model could potentially improve prediction of the Asian summer monsoon onset.

关键词： soil moisture remote sensing AMSR-E and ASM onset

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