南海局地生成的台风简称土台风,西北太平洋生成进入南海的台风简称洋台风。土台风具有突发性强、路径复杂、预报难度大等特点,给区域防灾减灾带来挑战,亟须开展系统性统计研究以提升对其发生发展规律的认知。当前对南海土台风的研究相...南海局地生成的台风简称土台风,西北太平洋生成进入南海的台风简称洋台风。土台风具有突发性强、路径复杂、预报难度大等特点,给区域防灾减灾带来挑战,亟须开展系统性统计研究以提升对其发生发展规律的认知。当前对南海土台风的研究相对零散,存在长期资料系统分析不足以及与洋台风对比不充分等问题,限制对其气候特征的深入理解。文章基于1949—2024年中国气象局热带气旋最佳路径数据集,系统分析了南海土台风的频数、强度、路径及源地分布特征,并与洋台风进行对比,揭示其时空变化模式。主要结论:1)土台风年均生成5.86个,年内分布呈单峰型,6—10月为高发期(78.9%),其中9月最多(21.7%),年频数存在显著下降线性趋势(-0.05个·年^(-1));2)土台风中心最低气压年均值位于965.0~999.5hPa,存在显著的下降线性趋势,路径以西/西北行为主,源地多位于南海中北部;3)与洋台风相比,土台风强度偏弱,仅13.7%的土台风为台风及以上等级,而洋台风可达61.7%,土台风累积气旋能量指数(accumulated cyclone energy index,ACE)和持续天数都更少,但变化迅速,登陆比例更高,更具突发性与局地性。展开更多
Based on reanalysis data and CMIP6 simulations,this study investigates the distinct responses of the cross-equatorial flows(CEFs)over the Maritime Continent(MC)under the simultaneous summer condition of two types of E...Based on reanalysis data and CMIP6 simulations,this study investigates the distinct responses of the cross-equatorial flows(CEFs)over the Maritime Continent(MC)under the simultaneous summer condition of two types of ENSO:central Pacific(CP)and eastern Pacific(EP).Results indicate that CP ENSO tends to exert stronger impacts on CEF.In CP ENSO years,significant lower-level southerly anomalies can be observed across all CEF branches adjacent to MC,accompanied by broader and deeper upper-level northerly anomalies,indicating a well-organized strengthening of both upper-and lowerlevel CEFs.In contrast,CEF anomalies in EP ENSO years tend to be weaker,with significant meridional wind anomalies confined to the east of MC.The disparities in the CEF responses can be elucidated from the perspective of convection over MC,a crucial factor in triggering CEF.In CP ENSO years,westward-leaning sea surface temperature(SST)anomalies result in a distinct cooling in MC and suppressed convection above,driving pronounced CEF anomalies.Conversely,the absence of such organized SST cooling during EP ENSO results in weaker convective forcing and subdued CEF responses.Furthermore,historical simulations from 48 CMIP6 models are utilized to validate the observational findings.Results show that model simulations can successfully reproduce the stronger impacts of CP ENSO,with a remarkable intermodel consistency.This research contributes toward a comprehensive understanding of the diversity in the relationship between CEF and ENSO types,and has implications for seasonal forecasting of CEF variability.展开更多
AdshtT Marine stratocumulus clouds profoundly affect Earth's energy budget by reflecting solar radiation over extensive oceanic areas.Yet,after using a large-eddy simulation(LES)and a Lagrangian microphysics schem...AdshtT Marine stratocumulus clouds profoundly affect Earth's energy budget by reflecting solar radiation over extensive oceanic areas.Yet,after using a large-eddy simulation(LES)and a Lagrangian microphysics scheme(Super-Droplet Method,SDM)for entrainment-mixing studies,uncertainty remains in the grid resolution and super-droplet number concentration(SDNC)required for accurate homogeneity capture.This study analyzes the homogeneous mixing degree(HMD)and the Damkohler number(Da)in stratocumulus using an LES with SDM,from microphysical and dynamical perspectives,respectively.Results show that HMD and Da both display a top-to-base gradient,with more intense inhomogeneity near the cloud top and relatively homogeneous conditions toward the base,although the upper region is more complex.Even at a fine horizontal resolution of 12.5 m and vertical resolution of 2.5 m,HMD remains sensitive and does not converge,whereas Da converges at coarser grid spacings(up to horizontal and vertical spacings of 25 m and 10 m,respectively)in the mid-cloud region.Similarly,HMD requires an SDNC well above 128 per cell for near-complete convergence,while Da converges once SDNC exceeds about 16 per cell.This difference arises because HMD depends on microphysical details,thereby demanding a high SDNC to capture local droplet inhomogeneities,whereas Da reflects turbulence-evaporation timescales that converge more readily once extreme droplet gradients are resolved.We further find that HMD and Da exhibit a significant negative correlation,with stronger anti-correlations emerging under finer spatial resolutions,reinforcing their complementary roles in diagnosing mixing regimes.Overall,these findings provide guidelines for selecting numerical configurations in entrainment-mixing simulations,ensuring that both turbulence-driven and microphysical processes are adequately resolved,.展开更多
The atmospheric surface layer of the tropical coastal ocean is commonly very unstable and experiences weakwind conditions.How the latent(LE)and sensible(H)heat fluxes behave under such conditions are unclear because o...The atmospheric surface layer of the tropical coastal ocean is commonly very unstable and experiences weakwind conditions.How the latent(LE)and sensible(H)heat fluxes behave under such conditions are unclear because of the lack of observation stations in the tropics.Thus,this study aims to analyze LE and H and the microclimate parameters influencing them.The authors deployed an eddy covariance system in a tropical coastal region for seven months.The microclimate parameters investigated were wind speed(U),vapor pressure deficit(Δe),temperature difference(ΔT),wind-vapor pressure deficit(UΔe),wind-temperature difference(UΔT),and atmospheric stability(z/L),where z is height and L is the Monin–Obukhov length.On the daily time scale,the results show that LE was more associated with U thanΔe,while H was more related toΔT than U.Cross-wavelet analysis revealed the strong coherence in the LE-U relationship for periods between one and two days,and for H–ΔT,0.5 to 1 day.Correlation and regression analyses confirmed the time series analyses results,where strong positive correlation coefficients(r)were obtained between LE and U(r=0.494)and H andΔT(r=0.365).Compared to other water bodies,the transfer coefficient of moisture(CE N)was found to be small(=0.40×10^(-3))and independent of stability;conversely,the transfer coefficient of heat(CH N)was closer to literature values(=1.00×10^(-3))and a function of stability.展开更多
The Northwest Pacific subtropical high(NWPSH)significantly affects East Asian weather and climate,rendering the prediction of its intensity and location critically important.This study aims to evaluate the performance...The Northwest Pacific subtropical high(NWPSH)significantly affects East Asian weather and climate,rendering the prediction of its intensity and location critically important.This study aims to evaluate the performance of the Convolutional Long and Short-Term Memory(ConvLSTM)model for predicting the summertime 500 hPa geopotential height and NWPSH intensity and area at a lead time of three months,and to compare it with the dynamical models of the Nanjing University of Information Science and Technology Climate Forecast System(NUIST-CFS1.0)and the Canadian Seasonal to Interannual Prediction System Version 2(CanSIPSv2).The mean latitude-weighted RMSE(RMSE_(w)),anomaly correlation coefficient(ACC),and NWPSH indices are used as evaluation metrics.For both summer mean and monthly prediction,the ConvLSTM model outperforms the two dynamical models in terms of RMSE_(w) and ACC for the 500 hPa geopotential height over the western Pacific region.The correlation coefficients between the NWPSH intensity index predicted by the ConvLSTM model and the observations are higher than those obtained from the two dynamical models.Regarding the NWPSH area index,the ConvLSTM model shows more stable performance.Particularly in August,the improvement of the ConvLSTM model compared to the two dynamical models is more significant,indicating the robust capability in capturing late-summer circulation patterns.Therefore,the ConvLSTM model demonstrates significant potential for summer NWPSH prediction,offering a new perspective and approach for climate prediction in this region.展开更多
The frequency of marine heatwaves(MHWs)in the South China Sea(SCS)has increased recently.However,the relative roles of thermal and dynamic processes regulating the changes of sCs MHWs remain an open question.This stud...The frequency of marine heatwaves(MHWs)in the South China Sea(SCS)has increased recently.However,the relative roles of thermal and dynamic processes regulating the changes of sCs MHWs remain an open question.This study examines all long-lived MHWs(>10 days)in the SCS from 1982 to 2021,categorizing them into intensified and attenuated MHWs based on the overall trend of sea surface temperature during an MHW event.A mixed-layer heat budget analysis reveals that the thermal processes primarily driven by the latent heat flux are crucial in modulating the SCS MHWs,particularly for attenuated MHWs.However,under intensified conditions,the proportions of dynamically dominated MHWs(40%)is approximately comparable to that of thermally dominated ones(47%).This study highlights the significance of dynamic processes in shaping SCS MHWs and discusses the potential impacts induced by tropical cyclones on these MHWs.展开更多
The coastal regions of southern China experience the country's most frequent convective weather.Accurately representing the low-level upstream atmospheric state over the data-sparse South China Sea(SCS)is crucial ...The coastal regions of southern China experience the country's most frequent convective weather.Accurately representing the low-level upstream atmospheric state over the data-sparse South China Sea(SCS)is crucial for reliable convection predictions in numerical models.Utilizing 10 years of radiosonde observations launched over the SCS,this study presents the upstream offshore convective environments and evaluates the global model data performance including NCEP FNL,ERA5,CRA-40,JRA-3Q,and MERRA-2.Results show that thermodynamic state variables such as temperature and humidity exhibit greater biases than kinetic variables,particularly at low levels.Deeper-layer parameters exhibit smaller uncertainties,especially wind-related variables,while moisture-related parameters have the largest uncertainties,compared to shallower-layer parameters.All model data tend to underestimate the conditional instability and equilibrium level,while overestimating the condensation level,storm relative helicity(SRH),with minimal bias in lapse rate,convective inhibition,vertical wind shear(VWS),and mean winds.These biases primarily arise from the model data's underestimation of temperature and moisture below 700 hPa and lower wind speeds below 950 hPa.Among the global models,CRA-40 performs best in dynamic parameters,with highest correlation and lowest mean absolute error in low-level winds,SRH,VWS,and mean winds.ERA5 excels in thermodynamic parameters.Additional convective-permitting numerical experiments indicate that minor initial condition errors over the upstream ocean significantly affect coastal rainfall production.The rainfall production on windward coasts is most sensitive to the low-level air temperature errors during nocturnal hours,while the rainfall over the PRD is most sensitive to the low-level wind errors.展开更多
The Zebiak–Cane(ZC) model, renowned as a coupled ocean-atmosphere model specifically designed to simulate and predict El Niño-Southern Oscillation(ENSO), is an indispensable tool for ENSO studies. However, the o...The Zebiak–Cane(ZC) model, renowned as a coupled ocean-atmosphere model specifically designed to simulate and predict El Niño-Southern Oscillation(ENSO), is an indispensable tool for ENSO studies. However, the original ZC model exhibits certain biases in reproducing the ENSO–related sea surface temperature anomalies and heating anomalies, limiting its broader applicability. To improve the accuracy of ENSO simulation, we propose a modified ZC model based on Xie et al.(2015), named the MZC_XJH model, through refining the heating parameterization scheme. The performance in simulating the nonlinear SST–precipitation relationship in the MZC_XJH model is firstly elaborated. Then, we investigate the impacts of three key atmospheric parameters on ENSO simulation by conducting experiments with the MZC_XJH model. Through assessing the performance in simulating five fundamental ENSO metrics(amplitude, periodicity,seasonality, diversity, and skewness), we uncover that the sensitivities of simulated ENSO behaviors to different parameters are distinct. Moreover, we explain why a particular parameter greatly affects some simulated ENSO behaviors while others exert minor influence. We also reveal that the nonlinear effect due to the covariation of multi-parameters on ENSO simulation warrants careful consideration when tuning multi-parameters synchronously. Lastly, we present an updated version of the MZC_XJH model, in which some biases have been mitigated but some remain obvious. Although there are no universally optimal parameters that would ensure flawless performance in simulating every aspect of ENSO, this study provides a valuable reference for tuning atmospheric parameters in the MZC_XJH model, rendering the MZC_XJH model applicable to some research objectives.展开更多
This study investigates the vertical variations of aerosol size distribution (0.06–1µm) and cloud condensation nuclei(CCN) spectra over the Southern Ocean (SO) using aircraft observations from the SOCRATES campa...This study investigates the vertical variations of aerosol size distribution (0.06–1µm) and cloud condensation nuclei(CCN) spectra over the Southern Ocean (SO) using aircraft observations from the SOCRATES campaign.Results reveal a bimodal aerosol size distribution within the marine boundary layer (MBL),with peaks at diameters of~0.06µm and~0.65µm,dominated by sea-salt particles.Accumulation-mode aerosol concentrations decrease with altitude within the MBL,while Aitken-mode aerosol concentrations peak above the MBL (~2–3 km).Wind speed strongly correlates with coarse-mode aerosol concentration (R2=0.77),implicating sea spray as a major CCN source at low supersaturations (SS=0.1%).The altitudes of CCN concentration peaks shift from the MBL (<1 km,SS<0.4%) to the free troposphere (~2.5 km,SS>0.4%),suggesting new particle formation aloft,distinct from sea surface sources.These findings highlight the unique aerosol–CCN dynamics in the pristine SO,offering critical constraints for models simulating cloud–aerosol interactions in preindustrial-like environments.展开更多
文摘南海局地生成的台风简称土台风,西北太平洋生成进入南海的台风简称洋台风。土台风具有突发性强、路径复杂、预报难度大等特点,给区域防灾减灾带来挑战,亟须开展系统性统计研究以提升对其发生发展规律的认知。当前对南海土台风的研究相对零散,存在长期资料系统分析不足以及与洋台风对比不充分等问题,限制对其气候特征的深入理解。文章基于1949—2024年中国气象局热带气旋最佳路径数据集,系统分析了南海土台风的频数、强度、路径及源地分布特征,并与洋台风进行对比,揭示其时空变化模式。主要结论:1)土台风年均生成5.86个,年内分布呈单峰型,6—10月为高发期(78.9%),其中9月最多(21.7%),年频数存在显著下降线性趋势(-0.05个·年^(-1));2)土台风中心最低气压年均值位于965.0~999.5hPa,存在显著的下降线性趋势,路径以西/西北行为主,源地多位于南海中北部;3)与洋台风相比,土台风强度偏弱,仅13.7%的土台风为台风及以上等级,而洋台风可达61.7%,土台风累积气旋能量指数(accumulated cyclone energy index,ACE)和持续天数都更少,但变化迅速,登陆比例更高,更具突发性与局地性。
基金supported by the National Natural Science Foundation of China(Grant No.42405029).
文摘Based on reanalysis data and CMIP6 simulations,this study investigates the distinct responses of the cross-equatorial flows(CEFs)over the Maritime Continent(MC)under the simultaneous summer condition of two types of ENSO:central Pacific(CP)and eastern Pacific(EP).Results indicate that CP ENSO tends to exert stronger impacts on CEF.In CP ENSO years,significant lower-level southerly anomalies can be observed across all CEF branches adjacent to MC,accompanied by broader and deeper upper-level northerly anomalies,indicating a well-organized strengthening of both upper-and lowerlevel CEFs.In contrast,CEF anomalies in EP ENSO years tend to be weaker,with significant meridional wind anomalies confined to the east of MC.The disparities in the CEF responses can be elucidated from the perspective of convection over MC,a crucial factor in triggering CEF.In CP ENSO years,westward-leaning sea surface temperature(SST)anomalies result in a distinct cooling in MC and suppressed convection above,driving pronounced CEF anomalies.Conversely,the absence of such organized SST cooling during EP ENSO results in weaker convective forcing and subdued CEF responses.Furthermore,historical simulations from 48 CMIP6 models are utilized to validate the observational findings.Results show that model simulations can successfully reproduce the stronger impacts of CP ENSO,with a remarkable intermodel consistency.This research contributes toward a comprehensive understanding of the diversity in the relationship between CEF and ENSO types,and has implications for seasonal forecasting of CEF variability.
基金supported by the National Natural Science Foundation of China(Grant Nos.42325503 and 42230604)The appointment of Chunsong Lu at Nanjing University of Information Science&Technology is partially supported by the Jiangsu Specially-Appointed Professor(Grant No.R2024T01).This research partly used the computational resources of Hokkaido University through the HPCI System Research Project(project IDs:hp200078,hp210059,hp220062,hp230166,and hp240151)and the computer facilities of the Center for Cooperative Work on Data Science and Computational Science,University of Hyogo.Shin-ichiro SHIMA was supported by JSPS KAKENHI,Grant 20H00225 and 23H00149and JST(Moonshot R and D)(Grant JPMJMS2286).We acknowledge the High-Performance Computing Center of the Nanjing University of Information Science and Technology for their support of this work.This study was also supported by the National Key Scientific and Technological Infrastructure project“Earth System Science Numerical Simulator Facility”(EarthLab,2024-EL-PT-000615).Chongzhi YIN would like to thank Lei Zhu for his generous support and informative discussions.
文摘AdshtT Marine stratocumulus clouds profoundly affect Earth's energy budget by reflecting solar radiation over extensive oceanic areas.Yet,after using a large-eddy simulation(LES)and a Lagrangian microphysics scheme(Super-Droplet Method,SDM)for entrainment-mixing studies,uncertainty remains in the grid resolution and super-droplet number concentration(SDNC)required for accurate homogeneity capture.This study analyzes the homogeneous mixing degree(HMD)and the Damkohler number(Da)in stratocumulus using an LES with SDM,from microphysical and dynamical perspectives,respectively.Results show that HMD and Da both display a top-to-base gradient,with more intense inhomogeneity near the cloud top and relatively homogeneous conditions toward the base,although the upper region is more complex.Even at a fine horizontal resolution of 12.5 m and vertical resolution of 2.5 m,HMD remains sensitive and does not converge,whereas Da converges at coarser grid spacings(up to horizontal and vertical spacings of 25 m and 10 m,respectively)in the mid-cloud region.Similarly,HMD requires an SDNC well above 128 per cell for near-complete convergence,while Da converges once SDNC exceeds about 16 per cell.This difference arises because HMD depends on microphysical details,thereby demanding a high SDNC to capture local droplet inhomogeneities,whereas Da reflects turbulence-evaporation timescales that converge more readily once extreme droplet gradients are resolved.We further find that HMD and Da exhibit a significant negative correlation,with stronger anti-correlations emerging under finer spatial resolutions,reinforcing their complementary roles in diagnosing mixing regimes.Overall,these findings provide guidelines for selecting numerical configurations in entrainment-mixing simulations,ensuring that both turbulence-driven and microphysical processes are adequately resolved,.
基金supported by a PETRONAS-Academia Collabora-tion Dialogue 2022 Grant[Grant number PACD 2022]from PETRONAS Research Sdn.Bhd。
文摘The atmospheric surface layer of the tropical coastal ocean is commonly very unstable and experiences weakwind conditions.How the latent(LE)and sensible(H)heat fluxes behave under such conditions are unclear because of the lack of observation stations in the tropics.Thus,this study aims to analyze LE and H and the microclimate parameters influencing them.The authors deployed an eddy covariance system in a tropical coastal region for seven months.The microclimate parameters investigated were wind speed(U),vapor pressure deficit(Δe),temperature difference(ΔT),wind-vapor pressure deficit(UΔe),wind-temperature difference(UΔT),and atmospheric stability(z/L),where z is height and L is the Monin–Obukhov length.On the daily time scale,the results show that LE was more associated with U thanΔe,while H was more related toΔT than U.Cross-wavelet analysis revealed the strong coherence in the LE-U relationship for periods between one and two days,and for H–ΔT,0.5 to 1 day.Correlation and regression analyses confirmed the time series analyses results,where strong positive correlation coefficients(r)were obtained between LE and U(r=0.494)and H andΔT(r=0.365).Compared to other water bodies,the transfer coefficient of moisture(CE N)was found to be small(=0.40×10^(-3))and independent of stability;conversely,the transfer coefficient of heat(CH N)was closer to literature values(=1.00×10^(-3))and a function of stability.
基金supported by the National Key Research and Development Program of China[grant number 2020YFA0608000]。
文摘The Northwest Pacific subtropical high(NWPSH)significantly affects East Asian weather and climate,rendering the prediction of its intensity and location critically important.This study aims to evaluate the performance of the Convolutional Long and Short-Term Memory(ConvLSTM)model for predicting the summertime 500 hPa geopotential height and NWPSH intensity and area at a lead time of three months,and to compare it with the dynamical models of the Nanjing University of Information Science and Technology Climate Forecast System(NUIST-CFS1.0)and the Canadian Seasonal to Interannual Prediction System Version 2(CanSIPSv2).The mean latitude-weighted RMSE(RMSE_(w)),anomaly correlation coefficient(ACC),and NWPSH indices are used as evaluation metrics.For both summer mean and monthly prediction,the ConvLSTM model outperforms the two dynamical models in terms of RMSE_(w) and ACC for the 500 hPa geopotential height over the western Pacific region.The correlation coefficients between the NWPSH intensity index predicted by the ConvLSTM model and the observations are higher than those obtained from the two dynamical models.Regarding the NWPSH area index,the ConvLSTM model shows more stable performance.Particularly in August,the improvement of the ConvLSTM model compared to the two dynamical models is more significant,indicating the robust capability in capturing late-summer circulation patterns.Therefore,the ConvLSTM model demonstrates significant potential for summer NWPSH prediction,offering a new perspective and approach for climate prediction in this region.
基金supported by the National Key R&D Program of China[grant number 2022YFF0801400]the National Natural Science Foundation of China [grant numbers 42376027 and W2441014]+2 种基金the Development Fund of the South China Sea Institute of Oceanology of the Chinese Academy of Sciences [grant number SCSIO202208]the Special Fund of the South China Sea Institute of Oceanology of the Chinese Academy of Sciences [grant number SCSIO2023QY01]the Science and Technology Projects in Guangzhou [grant number 202201010367]。
文摘The frequency of marine heatwaves(MHWs)in the South China Sea(SCS)has increased recently.However,the relative roles of thermal and dynamic processes regulating the changes of sCs MHWs remain an open question.This study examines all long-lived MHWs(>10 days)in the SCS from 1982 to 2021,categorizing them into intensified and attenuated MHWs based on the overall trend of sea surface temperature during an MHW event.A mixed-layer heat budget analysis reveals that the thermal processes primarily driven by the latent heat flux are crucial in modulating the SCS MHWs,particularly for attenuated MHWs.However,under intensified conditions,the proportions of dynamically dominated MHWs(40%)is approximately comparable to that of thermally dominated ones(47%).This study highlights the significance of dynamic processes in shaping SCS MHWs and discusses the potential impacts induced by tropical cyclones on these MHWs.
基金supported by the National Natural Science Foundation of China(Grant Nos.42030610,42275006,41805035,and 42305001)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515030210)+2 种基金the Guangdong Provincial Marine Meteorology Science Data Center(Grant No.2024B1212070014)the Open Project of the Xiamen Key Laboratory of Straits Meteorology(Grant Nos.HXQX202304 and 2024KF02)the Key Innovation Team of the China Meteorological Administration(Grant No.CMA2023ZD08)。
文摘The coastal regions of southern China experience the country's most frequent convective weather.Accurately representing the low-level upstream atmospheric state over the data-sparse South China Sea(SCS)is crucial for reliable convection predictions in numerical models.Utilizing 10 years of radiosonde observations launched over the SCS,this study presents the upstream offshore convective environments and evaluates the global model data performance including NCEP FNL,ERA5,CRA-40,JRA-3Q,and MERRA-2.Results show that thermodynamic state variables such as temperature and humidity exhibit greater biases than kinetic variables,particularly at low levels.Deeper-layer parameters exhibit smaller uncertainties,especially wind-related variables,while moisture-related parameters have the largest uncertainties,compared to shallower-layer parameters.All model data tend to underestimate the conditional instability and equilibrium level,while overestimating the condensation level,storm relative helicity(SRH),with minimal bias in lapse rate,convective inhibition,vertical wind shear(VWS),and mean winds.These biases primarily arise from the model data's underestimation of temperature and moisture below 700 hPa and lower wind speeds below 950 hPa.Among the global models,CRA-40 performs best in dynamic parameters,with highest correlation and lowest mean absolute error in low-level winds,SRH,VWS,and mean winds.ERA5 excels in thermodynamic parameters.Additional convective-permitting numerical experiments indicate that minor initial condition errors over the upstream ocean significantly affect coastal rainfall production.The rainfall production on windward coasts is most sensitive to the low-level air temperature errors during nocturnal hours,while the rainfall over the PRD is most sensitive to the low-level wind errors.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFF0802004)the Excellent Youth Natural Science Foundation of Jiangsu Province (BK20230061)+1 种基金the Joint Open Project of KLME&CIC-FEMD (Grant No.KLME202501)Jiangsu Innovation Research Group (Grant No.JSSCTD 202346)。
文摘The Zebiak–Cane(ZC) model, renowned as a coupled ocean-atmosphere model specifically designed to simulate and predict El Niño-Southern Oscillation(ENSO), is an indispensable tool for ENSO studies. However, the original ZC model exhibits certain biases in reproducing the ENSO–related sea surface temperature anomalies and heating anomalies, limiting its broader applicability. To improve the accuracy of ENSO simulation, we propose a modified ZC model based on Xie et al.(2015), named the MZC_XJH model, through refining the heating parameterization scheme. The performance in simulating the nonlinear SST–precipitation relationship in the MZC_XJH model is firstly elaborated. Then, we investigate the impacts of three key atmospheric parameters on ENSO simulation by conducting experiments with the MZC_XJH model. Through assessing the performance in simulating five fundamental ENSO metrics(amplitude, periodicity,seasonality, diversity, and skewness), we uncover that the sensitivities of simulated ENSO behaviors to different parameters are distinct. Moreover, we explain why a particular parameter greatly affects some simulated ENSO behaviors while others exert minor influence. We also reveal that the nonlinear effect due to the covariation of multi-parameters on ENSO simulation warrants careful consideration when tuning multi-parameters synchronously. Lastly, we present an updated version of the MZC_XJH model, in which some biases have been mitigated but some remain obvious. Although there are no universally optimal parameters that would ensure flawless performance in simulating every aspect of ENSO, this study provides a valuable reference for tuning atmospheric parameters in the MZC_XJH model, rendering the MZC_XJH model applicable to some research objectives.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.42430601,42175087)the Science and Technology Project of Gansu Province(Outstanding Youth Fund,Grant No.24JRRA386)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2024-jdzx04)。
文摘This study investigates the vertical variations of aerosol size distribution (0.06–1µm) and cloud condensation nuclei(CCN) spectra over the Southern Ocean (SO) using aircraft observations from the SOCRATES campaign.Results reveal a bimodal aerosol size distribution within the marine boundary layer (MBL),with peaks at diameters of~0.06µm and~0.65µm,dominated by sea-salt particles.Accumulation-mode aerosol concentrations decrease with altitude within the MBL,while Aitken-mode aerosol concentrations peak above the MBL (~2–3 km).Wind speed strongly correlates with coarse-mode aerosol concentration (R2=0.77),implicating sea spray as a major CCN source at low supersaturations (SS=0.1%).The altitudes of CCN concentration peaks shift from the MBL (<1 km,SS<0.4%) to the free troposphere (~2.5 km,SS>0.4%),suggesting new particle formation aloft,distinct from sea surface sources.These findings highlight the unique aerosol–CCN dynamics in the pristine SO,offering critical constraints for models simulating cloud–aerosol interactions in preindustrial-like environments.
