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The Persistence and Zonal Scale of atmospheric Dipolar Modes

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Advances in atmospheric sciences 2024年第3期41卷 478-492页

作者： Jie SONG state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg) Institute of Atmospheric Physics(IAP)Chinese Academy of SciencesBeijing 100029China

This study investigates the relationship between the persistence and the zonal scale of atmospheric dipolar modes(DMs). Results from the daily data of ERA5 and the long-term output of an idealized atmospheric model show that the atmospheric DMs with a broader(narrower) zonal scale dipolar structure possess a longer(shorter) persistence. A detailed vorticity budget analysis indicates that the persistence of a hemispheric-scale DM(1/1 DM) and a regional or sectoral DM(1/8 DM) in the model both largely rely on the persistence of the nonlinear eddy forcing. Linear terms can indirectly reduce the persistence of the anomalous nonlinear eddy forcing in a 1/8 DM by modifying the baroclinicity via the arousal of anomalous vertical motions. Therefore, the atmospheric DMs with a broader(narrower) zonal scale possess a longer(shorter) persistence because the effects of the linear terms are less(more) pronounced when the atmospheric DMs have better(worse) zonal symmetry. Further analyses show that the positive eddy feedback effect is weak or even absent in a 1/8DM and the high-frequency eddy forcing acts more like a concomitant phenomenon rather than a leading driving factor for a 1/8 DM. Thus, the hemispheric-scale DM and the regional or sectoral DMs are different, not only in their persistence but also in their dynamics.

关键词： NAM NAO eddy feedback persistence linear term

numerical simulations of Atlantic meridional overturning circulation(AMOC)from OMIP experiments and its sensitivity to surface forcing

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Journal of Oceanology and Limnology 2024年第2期42卷 454-467页

作者： Xiaowei WANG Yongqiang YU state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of sciences Beijing 100049China

Atlantic meridional overturning circulation(AMOC)plays an important role in transporting heat meridionally in the Earth’s climate system and is also a key metrical tool to verify oceanic general circulation *** OMIP(Ocean Model Intercomparison Project phase 1 and 2)simulations with LICOM3(version 3 of the lasg/IAP Climate System Ocean Model)developed at the state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg),Institute of atmospheric Physics(IAP),are compared in this *** simulations well reproduce the fundamental characteristics of the AMOC,but the OMIP1 simulation shows a significantly stronger AMOC than the OMIP2 *** the LICOM3 configurations are identical between these two experiments,any differences between them must be attributed to the surface forcing *** analysis suggests that sea surface salinity(SSS)differences should be mainly responsible for the enhanced AMOC in the OMIP1 simulation,but sea surface temperature(SST)also play an unignorable role in modulating *** the North Atlantic,where deep convection occurs,the SSS in OMIP1 is more saline than that in *** find that in the major region of deep convection,the change of SSS has more significant effect on density than the change of *** a result,the SSS was more saline than that in OMIP2,leading to stronger deep convection and subsequently intensify the *** conduct a series of numerical experiments with LICOM3,and the results confirmed that the changes in SSS have more significant effect on the strength of AMOC than the changes in SST.

关键词： oceanic general circulation model(OGCM) Atlantic meridional overturning(AMOC) surface forcing deep convection

Reduced Spring Precipitation Bias and Associated Physical Causes over South China in FGOALS-f3 Climate Models:Experiments with the Horizontal Resolutions

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Journal of Meteorological Research 2024年第4期38卷 784-804页

作者： Peng ZI Yimin LIU Jiandong LI Ruowen YANG Bian HE Qing BAO Department of atmospheric Science Yunnan UniversityKunming 650504 state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029

Considerable spring precipitation occurs over South China(SC),a region that is adjacent to large-scale Asian topography and *** reasonable simulation is crucial for improving regional climate *** study investigates spring precipitation biases over SC and their possible causes in atmosphere-only and coupled Flexible Global Ocean–Atmosphere–Land System finite-volume version 3(FGOALS-f3) models with different horizontal *** performance of spring precipitation simulation over SC varies across different FGOALS-f3 model versions,with the best reproducibility in the high-resolution coupled model(25 km).In the low-resolution atmosphere-only model(100–125 km),the precipitation dry bias over SC is closely linked to overestimated surface sensible forcing over the eastern Tibetan Plateau(TP),which weakens the subtropical anticyclone over the western Pacific(SAWP) through regional circulation *** contrast,the high-resolution atmosphere-only model further amplifies surface thermal forcing in the Asian continents,causing intensified land–sea thermal contrast between the Southeast Asian continents and western Pacific,enhanced southerly winds and SAWP,and increased water vapor transport into ***,the reduced middle–high level cold bias over 10°–30°N in the high-resolution atmosphere-only model intensifies the East Asian westerly jet and ascent over SC,leading to enhanced spring precipitation *** high-resolution coupled model simulation not only reduces sea surface cold bias over the Bay of Bengal,thus intensifying the Indian–Burma trough and strengthening low-level water vapor transport into SC,but also enhances ascent over *** a result,the high-resolution coupled model better reproduces the magnitude and pattern of spring precipitation over SC than its atmosphere-only *** with low-resolution models,the domain-mean spring precipitation dry bias decreases by 11.2% over SC in the high-resolution atmosphere-only mod

关键词： South China spring precipitation high resolution Flexible Global Ocean–Atmosphere–Land System finite-volume version 3(FGOALS-f3)models simulation

Evaluation and Projection of Population Exposure to Temperature Extremes over the Beijing−Tianjin−Hebei Region Using a High-Resolution Regional Climate Model RegCM4 Ensemble

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Advances in atmospheric sciences 2024年第6期41卷 1132-1146页

作者： Peihua QIN Zhenghui XIE Rui HAN Buchun LIU state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural Sciences(CAAS)Beijing 100081China

Temperature extremes over rapidly urbanizing regions with high population densities have been scrutinized due to their severe impacts on human safety and *** of all,the performance of the regional climate model RegCM4 with a hydrostatic or non-hydrostatic dynamic core in simulating seasonal temperature and temperature extremes was evaluated over the historical period of 1991–99 at a 12-km spatial resolution over China and a 3-km resolution over the Beijing−Tianjin−Hebei(JJJ)region,a typical urban agglomeration of *** of spatial distributions of temperature extremes over the JJJ region using RegCM4 with hydrostatic and non-hydrostatic cores showed high spatial correlations of more than 0.8 with the *** a warming climate,temperature extremes of annual maximum daily temperature(TXx)and summer days(SU)in China and the JJJ region showed obvious increases by the end of the 21st century while there was a general reduction in frost days(FD).The ensemble of RegCM4 with different land surface components was used to examine population exposure to temperature extremes over the JJJ *** exposure to temperature extremes was found to decrease in 2091−99 relative to 1991−99 over the majority of the JJJ region due to the joint impacts of increases in temperature extremes over the JJJ and population decreases over the JJJ region,except for downtown ***,changes in population exposure to temperature extremes were mainly dominated by future population ***,we quantified changes in exposure to temperature extremes with temperature increase over the JJJ *** study helps to provide relevant policies to respond future climate risks over the JJJ region.

关键词： CMIP6 convection-permitting population exposure RegCM4 temperature extremes

Shallow Convection Dataset Simulated by Three Different Large Eddy Models

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Advances in atmospheric sciences 2024年第4期41卷 754-766页

作者： Yaxin ZHAO Xiaocong WANG Yimin LIU Guoxiong WU Yanjie LIU College of Earth and Planetary sciences University of Chinese Academy of Sciences(UCAS)Beijing 100029China state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg) Institute of Atmospheric Physics(IAP)Chinese Academy of Sciences(CAS)Beijing 100029China

Shallow convection plays an important role in transporting heat and moisture from the near-surface to higher altitudes,yet its parameterization in numerical models remains a great challenge,partly due to the lack of high-resolution *** study describes a large eddy simulation(LES)dataset for four shallow convection cases that differ primarily in inversion strength,which can be used as a surrogate for real *** reduce the uncertainty in LES modeling,three different large eddy models were used,including SAM(System for atmospheric modeling),WRF(Weather Research and Forecasting model),and *** show that the different models generally exhibit similar behavior for each shallow convection case,despite some differences in the details of the convective *** addition to grid-averaged fields,conditionally sampled variables,such as in-cloud moisture and vertical velocity,are also provided,which are indispensable for calculation of the entrainment/detrainment *** the essentiality of the entraining/detraining process in the parameterization of cumulus convection,the dataset presented in this study is potentially useful for validation and improvement of the parameterization of shallow convection.

关键词： large eddy simulation SAM WRF UCLA-LES shallow convection entraining process

Future changes in precipitation and water availability over the Tibetan Plateau projected by CMIP6 models constrained by climate sensitivity

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atmospheric and Oceanic Science Letters 2024年第5期17卷 40-46页

作者： Hui Qiu Tianjun Zhou Liwei Zou Jie Jiang Xiaolong Chen Shuai Hu state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina University of the Chinese Academy of sciences BeijingChina

Precipitation projections over the Tibetan Plateau(TP)show diversity among existing studies,partly due to model *** to develop a reliable projection remains ***,based on the IPCC AR6–assessed likely range of equilibrium climate sensitivity(ECS)and the climatological precipitation performance,the authors constrain the CMIP6(phase 6 of the Coupled Model Intercomparison Project)model projection of summer precipitation and water availability over the *** best estimates of precipitation changes are 0.24,0.25,and 0.45 mm d^(−1)(5.9%,6.1%,and 11.2%)under the Shared Socioeconomic Pathway(SSP)scenarios of SSP1–2.6,SSP2–4.5,and SSP5–8.5 from 2050–2099 relative to 1965–2014,*** corresponding constrained projections of water availability measured by precipitation minus evaporation(P–E)are 0.10,0.09,and 0.22 mm d^(−1)(5.7%,4.9%,and 13.2%),*** increase of precipitation and P–E projected by the high-ECS models,whose ECS values are higher than the upper limit of the likely range,are about 1.7 times larger than those estimated by constrained ***,there is a larger increase in precipitation and P–E over the eastern TP,while the western part shows a relatively weak difference in precipitation and a drier trend in P–*** wetter TP projected by the high-ECS models resulted from both an approximately 1.2–1.4 times stronger hydrological sensitivity and additional warming of 0.6℃–1.2℃ under all three scenarios during 2050–*** study emphasizes that selecting climate models with climate sensitivity within the likely range is crucial to reducing the uncertainty in the projection of TP precipitation and water availability changes.

关键词： Tibetan plateau Climate sensitivity Precipitation projection Water availability projection

A Long-Time-Step-Permitting Tracer Transport Model on the Regular Latitude–Longitude Grid

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Advances in atmospheric sciences 2024年第3期41卷 493-508页

作者： Jianghao LI Li DONG key laboratory of Earth System modeling and Prediction China Meteorological AdministrationBeijing 100081China state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg) Institute of Atmospheric Physics(IAP)Chinese Academy of SciencesBeijing 100029China state key laboratory of Severe Weather(LaSW) Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081China College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China

If an explicit time scheme is used in a numerical model, the size of the integration time step is typically limited by the spatial resolution. This study develops a regular latitude–longitude grid-based global three-dimensional tracer transport model that is computationally stable at large time-step sizes. The tracer model employs a finite-volume flux-form semiLagrangian transport scheme in the horizontal and an adaptively implicit algorithm in the vertical. The horizontal and vertical solvers are coupled via a straightforward operator-splitting technique. Both the finite-volume scheme's onedimensional slope-limiter and the adaptively implicit vertical solver's first-order upwind scheme enforce monotonicity. The tracer model permits a large time-step size and is inherently conservative and monotonic. Idealized advection test cases demonstrate that the three-dimensional transport model performs very well in terms of accuracy, stability, and efficiency. It is possible to use this robust transport model in a global atmospheric dynamical core.

关键词： tracer transport numerical stability latitude–longitude grid

Ingredients-based Methodology and Fuzzy Logic Combined Short-Duration Heavy Rainfall Short-Range Forecasting:An Improved Scheme

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Journal of Tropical Meteorology 2024年第3期30卷 241-256页

作者： TIAN Fu-you XIA Kun SUN Jian-hua ZHENG Yong-guang HUA Shan National Meteorological Center Beijing100081 China state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(lasg) Institute of Atmospheric PhysicsChinese Academy of Sciences(IAP/CAS)Beijing 100029 China key laboratory of Cloud-Precipitation Physics and Severe Storms(LACS) Institute of Atmospheric PhysicsChinese Academy of Sciences(IAP/CAS)Beijing 100029 China

Short-duration heavy rainfall(SHR),as delineated by the National Meteorological Center of the China Me-teorological Administration,is characterized by hourly rainfall amounts no less than 20.0 *** is one of the most common convective weather phenomena that can cause severe ***-range forecasting of SHR is an important part of operational severe weather *** the present study,an improved objective SHR forecasting scheme was developed by adopting the ingredients-based methodology and using the fuzzy logic *** 1.0°×1.0°National Centers for Environmental Prediction(NCEP)final analysis data and the ordinary rainfall(0.1-19.9 mm h-1)and SHR observational data from 411 stations were used in the improved *** best lifted index,the total precipitable water,the 925 hPa specific humidity(Q 925),and the 925 hPa divergence(DIV 925)were selected as predictors based on objective *** distributed membership functions of predictors were obtained based on relative frequency *** weights of predictors were also objectively *** with a typhoon SHR case and a spring SHR case show that the main possible areas could be captured by the improved *** of SHR forecasts within 96 hours with NCEP global forecasts 1.0°×1.0°data initiated at 08:00 Beijing Time during the warm seasons in 2015 show the results were improved from both deterministic and probabilistic *** study provides an objectively feasible choice for short-range guidance forecasts of *** scheme can be applied to other convective phenomena.

关键词： ingredients-based methodology fuzzy logic approach probability of short-duration heavy rainfall(SHR) improved forecasting scheme objectively obtained membership functions

A teleconnection pattern of upper-tropospheric circulation anomalies over the Eurasian continent associated with the interannual variability of atmospheric convection over the tropical western North Pacific in July

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atmospheric and Oceanic Science Letters 2024年第3期17卷 20-24页

作者： Peishan Chen Riyu Lu state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences BeijingChina College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijingChina

热带西北太平洋大气对流的年际变化对东亚夏季气候有着显著影响,而且受到前冬ENSO的影响.然而,还有相当多的西北太平洋对流年际变化不能由前冬ENSO解释.本文表明,7月西北太平洋对流受到欧亚大陆对流层上层遥相关型的显著影响,且这一影... 详细信息

热带西北太平洋大气对流的年际变化对东亚夏季气候有着显著影响,而且受到前冬ENSO的影响.然而,还有相当多的西北太平洋对流年际变化不能由前冬ENSO解释.本文表明,7月西北太平洋对流受到欧亚大陆对流层上层遥相关型的显著影响,且这一影响与前冬ENSO的影响程度相当.该遥相关型表现为位于欧洲的气旋式环流异常,中亚的反气旋式环流异常和东亚带状延伸的气旋式环流异常,并表现为7月对流层上层环流的第一主模态.基于本文的结果并结合前人的研究,作者认为这一遥相关型能通过亚洲急流出口区附近的罗斯贝波破碎引起西北太平洋对流异常.

关键词：遥相关大气对流西北太平洋年际变化