A three-dimensional（3D） charging-discharging cloud resolution model was used to investigate the impact of the vertical velocity field on the charging processes and the formation of charge structure in a strong thund...A three-dimensional（3D） charging-discharging cloud resolution model was used to investigate the impact of the vertical velocity field on the charging processes and the formation of charge structure in a strong thunderstorm. The distribution and evolution of ice particle content and charges on ice particles were analyzed in different vertical velocity fields. The results show that the ice particles in the vertical velocity range from 1 to 5 m s-1obtained the most charge through charging processes during the lifetime of the thunderstorm. The magnitude of the charges could reach 1014 n C. Before the beginning of lightning activity,the charges produced in updraft region 2（updraft speed 13 m s-1） and updraft region 1（updraft speed between 5 and 13 m s-1） were relatively significant. The magnitudes of charge reached 1013 n C, which clearly impacted upon the early lightning activity. The vertical velocity conditions in the quasi-steady region（updraft speed between -1 and 1 m s-1） were the most conducive for charge separation on ice particles on different scales. Accordingly, a net charge structure always appeared in the quasi-steady and adjacent regions. Based on the results, a conceptual model of ice particle charging, charge separation, and charge structure formation in the flow field was constructed. The model helps to explain observations of the＂lightning hole＂ phenomenon.展开更多
模式分辨率对气候模式的模拟效果具有重要影响。然而,当前模式开发对于垂直分辨率的重视不够。以ENSO(厄尔尼诺-南方涛动)遥相关为例,利用CESM(Community Earth System Model)模式,探究不同模式垂直分辨率设置下模式模拟的ENSO对平流层...模式分辨率对气候模式的模拟效果具有重要影响。然而,当前模式开发对于垂直分辨率的重视不够。以ENSO(厄尔尼诺-南方涛动)遥相关为例,利用CESM(Community Earth System Model)模式,探究不同模式垂直分辨率设置下模式模拟的ENSO对平流层、对流层影响的差异,评估模式垂直分辨率在气候模拟中的重要性。结果表明,提高垂直分辨率可以显著改进模式对ENSO遥相关的模拟能力。以ECMWF(European Centre for Medium-Range Weather Forecasts)第五代再分析数据集(ERA5)为参照,ENSO对纬向平均温度的影响在北半球中高纬地区冬季呈现出“负正负”的三极子模态。CESM默认的垂直分辨率设置(L66)不能模拟出这一模态,而提高模式垂直分辨率(L103)后则可以较好地模拟出这个模态。对于水平分布而言,L66模拟的ENSO在对流层的信号与再分析资料相比明显偏强,L103则可以显著改善。同时,L103对ENSO影响平流层的模拟效果也比L66有所改善。进一步分析发现,L103模拟的行星波从对流层向平流层的传播更强,更接近再分析资料。提高垂直分辨率可以改善模式对大气波活动以及平流层-对流层动力耦合的模拟,重视模式的研发。展开更多
A global eddy-permitting ocean-ice coupled model with a horizontal resolution of 0.25° by 0.25° is estab- lished on the basis of Modular Ocean Model version 4 （MOM4） and Sea Ice Simulator （SIS）. Simulati...A global eddy-permitting ocean-ice coupled model with a horizontal resolution of 0.25° by 0.25° is estab- lished on the basis of Modular Ocean Model version 4 （MOM4） and Sea Ice Simulator （SIS）. Simulation results are compared with those of an intermediate resolution ocean-ice coupled model with a horizontal resolution of about 1° by 1°. The results show that the simulated ocean temperature, ocean current and sea ice concentration from the eddy-permitting model are better than those from the intermediate resolu- tion model. However, both the two models have the common problem of ocean general circulation models （OGCMs） that the majority of the simulated summer sea surface temperature （SST） is too warm while the majority of the simulated subsurface summer temperature is too cold. Further numerical experiments show that this problem can be alleviated by incorporating the non-breaking surface wave-induced vertical mixing into the vertical mixing scheme for both eddy-permitting and intermediate resolution models.展开更多
The numerical simulation of typhoons has been found to be very sensitive to the vertical resolution of the model.During the updating of the TRAMS model from version 1.0 to 3.0,the horizontal resolution has been increa...The numerical simulation of typhoons has been found to be very sensitive to the vertical resolution of the model.During the updating of the TRAMS model from version 1.0 to 3.0,the horizontal resolution has been increased from 36 km to 9 km,while the vertical layer number only increased from 55 to 65 layers.The lack of high vertical resolution limits the performance of the TRAMS model in typhoon forecasting to a certain extent.In order to study the potential improvement of typhoon forecasting by increasing the vertical resolution,this paper increases the vertical resolution of the TRAMS model from 65 to 125 layers for the first time for a comparative simulation test.The results of the case study with Typhoon Hato(2017)show that the model with high vertical resolution can significantly enhance the warm structure caused by water vapor flux convergence and vertical transport,thus accurately simulating the rapid strengthening process of the typhoon.Meanwhile,the model with 125-layer vertical resolution can simulate the asymmetric structural characteristics of the wind field,which are closer to the observations and can help to reduce the bias in typhoon track forecasting.The improvement of vertical resolution is also trialed by using the batch test results of several landfalling typhoons in 2016-2017.The experimental results show that the typhoon forecast of the model becomes consistent with the observations only when the number of vertical layers of the model increases to about 125 layers,which in turn causes a large computational burden.In the next step,we will try to solve the computational burden problem caused by ultra-high vertical resolution with the top boundary nesting technique,and realize the application of high vertical resolution in the actual operation of the TRAMS model.展开更多
The impacts of stratospheric initial conditions and vertical resolution on the stratosphere by raising the model top,refining the vertical resolution,and the assimilation of operationally available observations,includ...The impacts of stratospheric initial conditions and vertical resolution on the stratosphere by raising the model top,refining the vertical resolution,and the assimilation of operationally available observations,including conventional and satellite observations,on continental U.S.winter short-range weather forecasting,were investigated in this study.The initial and predicted wind and temperature profiles were analyzed against conventional observations.Generally,the initial wind and temperature bias profiles were better adjusted when a higher model top and refined vertical resolution were used.Negative impacts were also observed in both the initial wind and temperature profiles,over the lower troposphere.Different from the results by only raising the model top,the assimilation of operationally available observations led to significant improvements in both the troposphere and stratosphere initial conditions when a higher top was used.Predictions made with the adjusted stratospheric initial conditions and refined vertical resolutions showed generally better forecasting skill.The major improvements caused by raising the model top with refined vertical resolution,as well as those caused by data assimilation,were in both cases located in the tropopause and lower stratosphere.Negative impacts were also observed in the predicted near surface wind and lower-tropospheric temperature.These negative impacts were related to the uncertainties caused by more stratospheric information,as well as to some physical processes.A case study shows that when we raise the model top,put more vertical layers in stratosphere and apply data assimilation,the precipitation scores can be slightly improved.However,more analysis is needed due to uncertainties brought by data assimilation.展开更多
The vertical resolution of LICOM1.0 (LASG/IAP Climate System Ocean Model, version 1.0) is adjusted by increasing the level amount within the upper 150 m while keeping the total of levels. It is found that the eastern ...The vertical resolution of LICOM1.0 (LASG/IAP Climate System Ocean Model, version 1.0) is adjusted by increasing the level amount within the upper 150 m while keeping the total of levels. It is found that the eastern equatorial Pacific cold tongue is sensitive to the adjustment. Compared with the simulation of the original level scheme, the adjusting yields a more realistic structure of cold tongue extending from the coast of Peru to the equator, as well as a temperature minimum at Costa Rica coast, north of the cold tongue. In the original scheme experiment, the sharp heating by net surface heat flux at the beginning of spin-up leads to a great warm- ing in the eastern equatorial Pacific Ocean. The weak vertical advection due to a too thick mixed layer in the coarse vertical structure also accounts for the warm bias. The fact that most significant improvements of the upper 50 m temperature appear at the region of the thinnest mixed layer indicates the necessity of fine vertical resolution for the eastern equatorial Pacific Ocean. However, the westward extension of equatorial cold tongue, a defect in the original scheme, gets even more serious in the adjusting scheme due to the intensi- fied vertical velocity and hence vertical advection in the central-eastern equatorial Pacific Ocean.展开更多
基金Supported by the National Natural Science Foundation of China(41205001 and 41030960)National(Key)Basic Research and Development(973)Program of China(2014CB441406)+1 种基金Basic Research Funds of CAMS(2012Y005 and 2013Z006)LASW State Key Laboratory Special Fund
文摘A three-dimensional（3D） charging-discharging cloud resolution model was used to investigate the impact of the vertical velocity field on the charging processes and the formation of charge structure in a strong thunderstorm. The distribution and evolution of ice particle content and charges on ice particles were analyzed in different vertical velocity fields. The results show that the ice particles in the vertical velocity range from 1 to 5 m s-1obtained the most charge through charging processes during the lifetime of the thunderstorm. The magnitude of the charges could reach 1014 n C. Before the beginning of lightning activity,the charges produced in updraft region 2（updraft speed 13 m s-1） and updraft region 1（updraft speed between 5 and 13 m s-1） were relatively significant. The magnitudes of charge reached 1013 n C, which clearly impacted upon the early lightning activity. The vertical velocity conditions in the quasi-steady region（updraft speed between -1 and 1 m s-1） were the most conducive for charge separation on ice particles on different scales. Accordingly, a net charge structure always appeared in the quasi-steady and adjacent regions. Based on the results, a conceptual model of ice particle charging, charge separation, and charge structure formation in the flow field was constructed. The model helps to explain observations of the＂lightning hole＂ phenomenon.
文摘模式分辨率对气候模式的模拟效果具有重要影响。然而,当前模式开发对于垂直分辨率的重视不够。以ENSO(厄尔尼诺-南方涛动)遥相关为例,利用CESM(Community Earth System Model)模式,探究不同模式垂直分辨率设置下模式模拟的ENSO对平流层、对流层影响的差异,评估模式垂直分辨率在气候模拟中的重要性。结果表明,提高垂直分辨率可以显著改进模式对ENSO遥相关的模拟能力。以ECMWF(European Centre for Medium-Range Weather Forecasts)第五代再分析数据集(ERA5)为参照,ENSO对纬向平均温度的影响在北半球中高纬地区冬季呈现出“负正负”的三极子模态。CESM默认的垂直分辨率设置(L66)不能模拟出这一模态,而提高模式垂直分辨率(L103)后则可以较好地模拟出这个模态。对于水平分布而言,L66模拟的ENSO在对流层的信号与再分析资料相比明显偏强,L103则可以显著改善。同时,L103对ENSO影响平流层的模拟效果也比L66有所改善。进一步分析发现,L103模拟的行星波从对流层向平流层的传播更强,更接近再分析资料。提高垂直分辨率可以改善模式对大气波活动以及平流层-对流层动力耦合的模拟,重视模式的研发。
基金The Key Project of the National Science Foundation of China under contract No. 40730842the "973" Project of China under contract No. 2010CB950303+2 种基金the Scientific Research Foundation of the First Institute of Oceanography, State Oceanic Administration of Chinaunder contract No. 2011T02the National Key Technology R&D Program of China under contract No. 2011BAC03B02the Key Supercomputing Science-Technology Project of Shandong Province of China under contract No. 2011YD01107
文摘A global eddy-permitting ocean-ice coupled model with a horizontal resolution of 0.25° by 0.25° is estab- lished on the basis of Modular Ocean Model version 4 （MOM4） and Sea Ice Simulator （SIS）. Simulation results are compared with those of an intermediate resolution ocean-ice coupled model with a horizontal resolution of about 1° by 1°. The results show that the simulated ocean temperature, ocean current and sea ice concentration from the eddy-permitting model are better than those from the intermediate resolu- tion model. However, both the two models have the common problem of ocean general circulation models （OGCMs） that the majority of the simulated summer sea surface temperature （SST） is too warm while the majority of the simulated subsurface summer temperature is too cold. Further numerical experiments show that this problem can be alleviated by incorporating the non-breaking surface wave-induced vertical mixing into the vertical mixing scheme for both eddy-permitting and intermediate resolution models.
基金National Natural Science Foundation of China(U2142213)Open Grants of the State Key Laboratory of Severe Weather(2022LASW-B16)+1 种基金Guangdong Basic and Applied Basic Research Foundation(2022A1515011870)Special Program for Innovation and Development of China Meteorological Administration(CXFZ2021Z006,CXFZ2022P026)。
文摘The numerical simulation of typhoons has been found to be very sensitive to the vertical resolution of the model.During the updating of the TRAMS model from version 1.0 to 3.0,the horizontal resolution has been increased from 36 km to 9 km,while the vertical layer number only increased from 55 to 65 layers.The lack of high vertical resolution limits the performance of the TRAMS model in typhoon forecasting to a certain extent.In order to study the potential improvement of typhoon forecasting by increasing the vertical resolution,this paper increases the vertical resolution of the TRAMS model from 65 to 125 layers for the first time for a comparative simulation test.The results of the case study with Typhoon Hato(2017)show that the model with high vertical resolution can significantly enhance the warm structure caused by water vapor flux convergence and vertical transport,thus accurately simulating the rapid strengthening process of the typhoon.Meanwhile,the model with 125-layer vertical resolution can simulate the asymmetric structural characteristics of the wind field,which are closer to the observations and can help to reduce the bias in typhoon track forecasting.The improvement of vertical resolution is also trialed by using the batch test results of several landfalling typhoons in 2016-2017.The experimental results show that the typhoon forecast of the model becomes consistent with the observations only when the number of vertical layers of the model increases to about 125 layers,which in turn causes a large computational burden.In the next step,we will try to solve the computational burden problem caused by ultra-high vertical resolution with the top boundary nesting technique,and realize the application of high vertical resolution in the actual operation of the TRAMS model.
基金National Key Research and Development Project(2018YFC1505706)Fund of Southern Marine Science and Engineering Guangdong Laboratory(Zhanjiang)(ZJW-2019-08)+3 种基金Program for Scientific Research Start-up Funds of GDOU(R17061)Project of Enhancing School with Innovation of GDOU(230419053)Projects(Platforms)for Construction of Top-ranking Disciplines of GDOU(231419022)Special Funds of Central Finance to Support the Development of Local Colleges and Universities(000041)
文摘The impacts of stratospheric initial conditions and vertical resolution on the stratosphere by raising the model top,refining the vertical resolution,and the assimilation of operationally available observations,including conventional and satellite observations,on continental U.S.winter short-range weather forecasting,were investigated in this study.The initial and predicted wind and temperature profiles were analyzed against conventional observations.Generally,the initial wind and temperature bias profiles were better adjusted when a higher model top and refined vertical resolution were used.Negative impacts were also observed in both the initial wind and temperature profiles,over the lower troposphere.Different from the results by only raising the model top,the assimilation of operationally available observations led to significant improvements in both the troposphere and stratosphere initial conditions when a higher top was used.Predictions made with the adjusted stratospheric initial conditions and refined vertical resolutions showed generally better forecasting skill.The major improvements caused by raising the model top with refined vertical resolution,as well as those caused by data assimilation,were in both cases located in the tropopause and lower stratosphere.Negative impacts were also observed in the predicted near surface wind and lower-tropospheric temperature.These negative impacts were related to the uncertainties caused by more stratospheric information,as well as to some physical processes.A case study shows that when we raise the model top,put more vertical layers in stratosphere and apply data assimilation,the precipitation scores can be slightly improved.However,more analysis is needed due to uncertainties brought by data assimilation.
文摘The vertical resolution of LICOM1.0 (LASG/IAP Climate System Ocean Model, version 1.0) is adjusted by increasing the level amount within the upper 150 m while keeping the total of levels. It is found that the eastern equatorial Pacific cold tongue is sensitive to the adjustment. Compared with the simulation of the original level scheme, the adjusting yields a more realistic structure of cold tongue extending from the coast of Peru to the equator, as well as a temperature minimum at Costa Rica coast, north of the cold tongue. In the original scheme experiment, the sharp heating by net surface heat flux at the beginning of spin-up leads to a great warm- ing in the eastern equatorial Pacific Ocean. The weak vertical advection due to a too thick mixed layer in the coarse vertical structure also accounts for the warm bias. The fact that most significant improvements of the upper 50 m temperature appear at the region of the thinnest mixed layer indicates the necessity of fine vertical resolution for the eastern equatorial Pacific Ocean. However, the westward extension of equatorial cold tongue, a defect in the original scheme, gets even more serious in the adjusting scheme due to the intensi- fied vertical velocity and hence vertical advection in the central-eastern equatorial Pacific Ocean.
