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Journal of Meteorological Research 2017年第3期31卷 468-475页

作者： Lei ZHANG Tim LI climate Dynamics Research Center and Earth System modeling Center International Laboratory on Climate and Environment ChangeNanjing University of Information Science & Technology Department of Atmospheric Sciences University of Hawaii

Arctic sea ice concentration （ASIC） in boreal autumn exhibits prominent interannual variability since 1979. The physical mechanism responsible for the year-to-year variation of ASIC is investigated through observational data analyses and idealized numerical modeling. It is found that the ASIC interannual variability is closely associated with the anomalous meridional circulations over the Northern Hemisphere, which is further linked with the tropical sea surface temperature （SST） forcing. A tropics-wide SST cooling anomaly leads to an enhanced meridional SST gradi- ent to the north of the equator in boreal summer, generating strengthened and northward shifting Hadley circulation over the Northern Hemisphere. Consequently, the meridional circulations are enhanced and pushed poleward, lead- ing to an enhanced descending motion at the North Pole, surrounded by an ascending motion anomaly; the surface outflow turns into easterly anomalies, opposing the mean-state winds. As a result, positive cloudiness and weakened surface wind speed emerge, which reduce ASIC through changes in the surface latent heat flux and the downward longwave radiation.

关键词： Arctic sea ice variability interannual variability tropical forcing meridional circulations

Numerical simulation and cause analysis of persistent summer drought during the 1920s in eastern China

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Science China Earth Sciences 2022年第5期65卷 966-982页

作者： Meng LUO Jinming FENG Zhongfeng XU Jun WANG Li DAN Yunnan climate Center Kunming 650034China Key lab of Regional climate-environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

In the late 1920’s,a mega-drought in China resulted in widespread crop failure and *** evidence suggests that this drought belonged to a dry period ranging from approximately 1922 to *** understand the characteristics and the cause of this persistent drought period,we combined various data,including observations,tree ring proxy data,reanalysis data,simulation results of the Fifth Phase of the Coupled Model Intercomparison Project and numerical downscaling *** results show that during 1922-1932,most regions in eastern China suffered from a persistent drought that lasted for six years,and the maximum negative precipitation anomaly reached−1.5 times the standard *** its spatial coverage,duration,and strength,the 1920s drought was unique for the 20th *** 1920s drought was primarily caused by internal *** easterlies in lower latitudes,strong monsoon circulation,and abnormally high geopotential heights at middle and upper levels were responsible for the 1920s drought conditions in eastern China;these drought conditions could be further attributed to the joint impact of the Atlantic Multidecadal Oscillation,Pacific Decadal Oscillation and Indian Ocean Basin Mode.

关键词： Drought 1920s Eastern China East Asia Summer Monsoon Regional climate Model Atlantic Multidecadal Oscillation Pacific Decadal Oscillation Indian Ocean Basin Mode

Influence of Human Activities on Wintertime Haze-Related Meteorological Conditions over the Jing–Jin–Ji Region

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Engineering 2021年第8期7卷 1185-1192页

作者： Ying Xu Yanju Liu Zhenyu Han Botao Zhou Yihui Ding Jie Wuc Tongfei Tian Rouke Li Jing Wang National climate Center China Meteorological AdministrationBeijing 100081China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China School of Geography and environmental Engineering Gannan Normal UniversityGanzhou 341000China Camford Royal School Beijing 100093China climate and environment modeling lab Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China

This work analyzes and discusses the influence of human activities on the meteorological conditions related to winter haze events in Beijing,Tianjin,and Hebei(i.e.,the Jing-Jin-Ji region)during 1961-2016,using the results of two numerical simulation experiments based on the Community Atmosphere Model version 5.1.1(http://***/models/cesm1.0/cam/docs/ug5_1_1/***)used in the international climate Variability and Predictability Programme(CLIVAR)climate of the 20th Century Detection and Attribution Project(C20C+D&A).The results show that,under the influence of human activities,the changes in dynamical and thermal meteorological conditions related to winter haze events in the Jing–Jin–Ji region are conducive to the formation and accumulation of haze,and prevent the diffusion of *** dynamical conditions mainly include the obvious weakening of the East Asian winter monsoon(EAWM)and the enhancement of the near-surface anomalous southerly *** thermal conditions include the obvious increase in surface temperature,and the enhancement of water vapor transport and near-surface *** relative contribution of dynamical and thermal conditions to the variation of haze days in the Jing-Jin-Ji region is analyzed using statistical *** results show that the contribution of human activities to the increase of haze days in the Jing-Jin-Ji region is greater than that of natural forcing for the study *** be specific,the dynamical meteorological factors contribute more to the haze days than the thermal meteorological *** contribution of thermal meteorological factors is basically the same in both scenarios.

关键词： Meteorological conditions Human activities Haze Jing-Jin-Ji region

A New Parameterization of Canopy Radiative Transfer for Land Surface Radiation Models

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Advances in Atmospheric Sciences 2017年第5期34卷 613-622页

作者： Feng ZHANG Yadong LEI Jia-Ren YAN Jian-Qi ZHAO Jiangnan LI Qiudan DAI Key laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisasterNanjing University of Information Science & Technology State Key laboratory of Numerical modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences Canadian Center for climate modeling and Analysis University of Victoria

A new parameterization of canopy asymmetry factor on phase function,which is dependent on the leaf normal distribution and leaf reflection/transmission,is derived. This new parameterization is much more accurate than the existing scheme. In addition,the new solutions for both the diffuse and direct radiation can be obtained using the Eddington approximation. It is found that the direct radiation can be described as a function of the diffuse radiation. This new approach offers a substantial improvement in accuracy,as compared with the hemispheric constant method,for both isotropic and anisotropic cases. Given the analytical nature of the solution and its high accuracy,we recommend the new parameterization for application in land surface radiation modeling.

关键词： radiative transfer canopy asymmetry factor Eddington approximation

Spatiotemporal trends of PM_(2.5) and its major chemical components at urban sites in Canada

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Journal of environmental Sciences 2021年第5期33卷 1-11页

作者： Huanbo Wang Leiming Zhang Irene Cheng Xiaohong Yao Ewa Dabek-Zlotorzynska School of environment and Resource Southwest University of Science and TechnologyMianyang 621010China Air Quality Research Division Science and Technology BranchEnvironment and Climate Change CanadaTorontoCanada lab of Marine environmental Science and Ecology Ministry of EducationOcean University of ChinaQingdao 266100China Air Quality Research Division Science and Technology BranchEnvironment and Climate Change CanadaOttawaCanada

To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM_(2.5) data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM_(2.5) collected at seven urban and two rural sites during 2010-2016 were analyzed to characterize geographical and seasonal patterns and associated potential causes. Site-specific seven-year mean gravimetric PM_(2.5) mass concentrations ranged from 5.7 to 9.6 μg/m^(3). Seven-year mean concentrations of SO_(4)^(2-), NO_(3)^(-), NH_(4)^(+), organic carbon(OC), and elemental carbon(EC) were in the range of 0.68 to 1.6, 0.21 to 1.5, 0.27 to 0.71, 1.1 to 1.9, and 0.37 to 0.71 μg/m^(3), accounting for 10.8%-18.1%, 3.7%-16.7%, 4.7%-7.4%, 18.4%-21.0%, and 6.4%-10.6%, respectively, of gravimetric PM_(2.5) mass. PM_(2.5) and its five major chemical components showed higher concentrations in southeastern Canada and lower values in Atlantic Canada, with the seven-year mean ratios between the two regions being on the order of 1.7 for PM_(2.5) and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO_(4)^(2-) and NH_(4)^(+) were comparable, while those of NO_(3)^(-), OC, and EC were around 20%, 40%-50%, and 70%-80%, respectively, higher at urban than rural sites, indicating the regional scale impacts of SO_(4)^(2-) and NH_(4)^(+) and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO_(4)^(2-) and wintertime peaks for NO_(3)^(-), but those of NH_(4)^(+), OC, and EC exhibited different seasonality at different locations.

关键词： Fine particulate matter Aerosol chemical composition Monitoring network

The Effects of Line-Wing Cutoff in LBL Integration on Radiation Calculations

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Acta meteorologica Sinica 2008年第2期22卷 248-255页

作者：张华石广玉刘毅 laboratory for climate Studies of China Meteorological Administration National Climate Center State Key laboratory of Numerical modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics laboratory for Middle Atmosphere and Global environment Observation (LAGEO) Institute of Atmospheric Physics

There are three basic methods in radiative transfer calculations, i.e., line-by-line （LBL） integration, correlated k-distribution method, and band model. The LBL integration is the most accurate of all, in which, there are two quadrature algorithms named in this paper as integration by lines and by sampling points when calculating atmospheric transmittance in the considered wavenumher region. Because the LBL integration is the most expensive of all, it is necessary and important to save calculation time hut increase calculation speed when it is put into use in the daily operation in atmospheric remote sensing and atmospheric sounding. A simplified LBL method is given in this paper on the basis of integration by lines, which increases computational speed greatly with keeping the same accuracy. Then, we discuss the effects of different cutoff schemes on atmospheric absorption coefficient, transmittance, and cooling rate under both of accurate and simplified LBL methods in detail. There are four cutoff schemes described in this paper, i.e., CUTOFFs 1, 2, 3, and 4. It is shown by this numerical study that the way to cut off spectral line-wing has a great effect on the accuracy and speed of radiative calculations. The relative errors of the calculated absorption coefficients for CUTOFF 2 are the largest under different pressures, while for CUTOFF 1, they are less than 2% at most of sampling points and for CUTOFFs 3 or 4, they are almost less than 5% in the calculated spectral region, however, the calculation time is reduced greatly. We find in this study that the transmittance in the lower atmosphere is not sensitive to different LBL methods and different cutoff schemes. Whereas for the higher atmosphere, the differences of transmittance results between CUTOFF 2 and each of other three cutoff schemes are the biggest of all no matter for the accurate LBL or for the simplified LBL integrations. By comparison, the best and optimized cutoff scheme is given in this paper fina

关键词： LBL (line-by-line) integration line-wing cutoff absorption coefficient transmittance cooling rate

Evaluation of the Tropical Variability from the Beijing climate Center's Real-Time Operational Global Ocean Data Assimilation System

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Advances in Atmospheric Sciences 2016年第2期33卷 208-220页

作者： Wei ZHOU Mengyan CHEN Wei ZHUANG Fanghua XU Fei ZHENG Tongwen WU Xin WANG laboratory for climate Studies National Climate Center China Meteorological Administration State Key laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of Sciences Ministry of Education Key laboratory for Earth System modeling and Center for Earth System ScienceTsinghua University International Center for climate and environment Science Institute of Atmospheric PhysicsChinese Academy of Sciences

The second-generation Global Ocean Data Assimilation System of the Beijing climate Center （BCC_GODAS2.0） has been run daily in a pre-operational mode. It spans the period 1990 to the present day. The goal of this paper is to introduce the main components and to evaluate BCC_GODAS2.0 for the user community. BCC_GODAS2.0 consists of an observational data preprocess, ocean data quality control system, a three-dimensional variational （3DVAR） data assimilation, and global ocean circulation model [Modular Ocean Model 4 （MOM4）]. MOM4 is driven by six-hourly fluxes from the National Centers for environmental Prediction. Satellite altimetry data, SST, and in-situ temperature and salinity data are assimilated in real time. The monthly results from the BCC_GODAS2.0 reanalysis are compared and assessed with observations for 1990-201 I. The climatology of the mixed layer depth of BCC_GODAS2.0 is generally in agreement with that of World Ocean Atlas 2001. The modeled sea level variations in the tropical Pacific are consistent with observations from satellite altimetry on interannual to decadal time scales. Performances in predicting variations in the SST using BCC_GODAS2.0 are evaluated. The standard deviation of the SST in BCC_GODAS2.0 agrees well with observations in the tropical Pacific. BCC_GODAS2.0 is able to capture the main features of E1 Nifio Modoki I and Modoki II, which have different impacts on rainfall in southern China. In addition, the relationships between the Indian Ocean and the two types of E1 Nino Modoki are also reproduced.

关键词： operational oceanography global ocean 3DVAR E1 Nifio interannual variability

Wintertime extreme precipitation event over southern China and its typical circulation features

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Chinese Science Bulletin 2014年第10期59卷 1036-1044页

作者： Haifeng Zong Cholaw Bueh Liren Ji The International Center for climate and environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences State Key laboratory of Numerical modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

This study objectively defined an extreme precipitation event(EPE)over southern China and investigated the associated typical circulation pattern on the intraseasonal time *** occurrence of the EPE resulted from the joint operations of anomalous circulations over the subtropics and mid-high *** the EPE,simultaneous enhancements of the trough over the Bay of Bengal(BBT)and the Western Pacific subtropical high(WPSH)facilitated the abundant water vapor conditions over southern China,whereas the weakened East Asian major trough(EAT)led to a moderate cold air invasion to that region,producing a persistent convergence zone over southern *** train pattern in North Atlantic and Europe may be viewed as precursory signals for the EPE over southern China,and it contributed to the Rossby wave propagation in association with the *** wave packets propagated toward East Asia mainly along the North African-Asian subtropical westerly jet ***-frequency disturbances along this waveguide contributed to the enhancement of the BBT and WPSH and the weakening of the EAT,constituting favorable circulation conditions for the EPE.

关键词： Extreme precipitation event Troughover the Bay of Bengal - Western Pacific subtropicalhigh Precursory signal

Decadal Changes in Interannual Dependence of the Bay of Bengal Summer Monsoon Onset on ENSO Modulated by the Pacific Decadal Oscillation

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Advances in Atmospheric Sciences 2019年第12期36卷 1404-1416页

作者： Xiaofei WU Jiangyu MAO School of Atmospheric Sciences/Plateau Atmosphere and environment Key laboratory of Sichuan Province/Joint laboratory of climate and environment Change Chengdu University of Information TechnologyChengdu 610225China State Key laboratory of Numerical modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

Interannual variations of the Bay of Bengal summer monsoon (BOBSM) onset in association with El Ni-o-Southern Oscillation (ENSO) are reexamined using NCEP1, JRA-55 and ERA20C atmospheric and Hadley sea surface temperature (SST) reanalysis datasets over the period 1900-2017. Decadal changes exist in the dependence of the BOBSM onset on ENSO, varying with the Pacific Decadal Oscillation (PDO). A higher correlation between the BOBSM onset and ENSO arises during the warm PDO epochs, with distinct late (early) onsets following El Ni-o (La Ni-a) events. In contrast, less significant correlations occur during the cold PDO epochs. The mechanism for the PDO modulating the ENSO-BOBSM onset relationship is through the variations in SST anomaly (SSTA) patterns. During the warm PDO epochs, the superimpositions of the PDO-related and ENSO-related SSTAs lead to the SSTA distribution of an El Ni-o (La Ni-a) event exhibiting significant positive (negative) SSTAs over the tropical central-eastern Pacific and Indian Ocean along with negative (positive) SSTAs, especially over the tropical western Pacific (TWP), forming a strong zonal interoceanic SSTA gradient between the TWP and tropical Indian Ocean. Significant anomalous lower tropospheric easterlies (westerlies) together with upper-tropospheric westerlies (easterlies) are thus induced over the BOB, favoring an abnormally late (early) BOBSM onset. During the cold PDO epochs, however, the superimpositions of PDO-related SSTAs with El Ni-o-related (La Ni-a-related) SSTAs lead to insignificant SSTAs over the TWP and a weak zonal SSTA gradient, without distinct circulation anomalies over the BOB favoring early or late BOBSM onsets.

关键词： decadal change Bay of Bengal summer monsoon onset ENSO Pacific Decadal Oscillation

The Impact of Soil Freezing/Thawing Processes on Water and Energy Balances

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Advances in Atmospheric Sciences 2011年第1期28卷 169-177页

作者：张霞孙菽芬 Key laboratory of Regional climate-environment Research for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Science State Key laboratory of Numerical modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Science

A frozen soil parameterization coupling of thermal and hydrological processes is used to investigate how frozen soil processes affect water and energy balances in seasonal frozen soil. Simulation results of soil liquid water content and temperature using soil model with and without the inclusion of freezing and thawing processes are evaluated against observations at the Rosemount field station. By comparing the simulated water and heat fluxes of the two cases, the role of phase change processes in the water and energy balances is analyzed. Soil freezing induces upward water flow towards the freezing front and increases soil water content in the upper soil layer. In particular, soil ice obviously prevents and delays the infiltration during rain at Rosemount. In addition, soil freezingthawing processes alter the partitioning of surface energy fluxes and lead the soil to release more sensible heat into the atmosphere during freezing periods.

关键词： frozen soil water and energy balances freezing/thawing processes surface flux