On small-meso scale, the sea ice dynamic characteristics are quite different from that on large scale. To model the sea ice dynamics on small-meso scale, a new elastic-viscous-plastic （EVP） constitutive model and a ...On small-meso scale, the sea ice dynamic characteristics are quite different from that on large scale. To model the sea ice dynamics on small-meso scale, a new elastic-viscous-plastic （EVP） constitutive model and a hybrid Lagrangian- Eulerian （HLE） numerical method are developed based on continuum theory. While a modified discrete element model （DEM） is introduced to model the ice cover at discrete state. With the EVP constitutive model, the numerical simulation for ice ridging in an idealized rectangular basin is carried out and the results are comparable with the analytical solution of jam theory. Adopting the HLE numerical model, the sea ice dynamic process is simulated in a vortex wind field. The furthering application of DEM is discussed in details for modeling the discrete distribution of sea ice. With this study, the mechanical and numerical models for sea ice dynamics can be improved with high precision and computational efficiency.展开更多
[Objective]The aim was to analyze the mesoscale and small scale system that influenced the strong rainfall in Hunan from June 18 to 20 in 2010. [Method] By dint of regular observation material and rainfall in regional...[Objective]The aim was to analyze the mesoscale and small scale system that influenced the strong rainfall in Hunan from June 18 to 20 in 2010. [Method] By dint of regular observation material and rainfall in regional automatic station, TBB of FY-2C geostationary meteorological satellite, characteristics and causes of one heavy rainfall event in Hunan Province on 18-20 June 2010 were studied. [Result] The rainstorm happened under the southwest warm and wet torrent at the edge of subtropical high when the ground cold air intruded, which triggered the release of unstable energy. The water vapor from Bay of Bengal and South China Sea sent abundant water vapor to south China. The water vapor strengthened, which synchronized with the rainstorm. The ground mesoscale convergence line and the mesoscale low pressure intensified the rainstorm. Changes of pressure field reflected the changes of rainfall and indicated the location and movement of heavy rainfall. [Conclusion] The study provided theoretical basis to understand the rainstorm formation mechanism and improve disaster prevention capacity.展开更多
[Objective] The research aimed to study the meso-scale characteristics of a hail process in Linyi area. [Method] By comprehensively using MICAPS conventional observation data, automatic encryption ground station, MM5 ...[Objective] The research aimed to study the meso-scale characteristics of a hail process in Linyi area. [Method] By comprehensively using MICAPS conventional observation data, automatic encryption ground station, MM5 model product and Doppler weather radar data, a strong convective hail weather process which happened in Shandong Peninsula and southeast of Shandong on May 30, 2010 was analyzed. The circulation background and physical mechanism of strong convection weather occurrence, the features of meso- and micro-scale systems were discussed. Some occurrence and development rules of such weather were found. [Result] The strong convective weather was mainly affected by the cold vortex and translot. The high-altitude northwest airflow, low-level southwest airflow, dry and cold air at the high layer, warm and wet air at the low layer, forward-tilting trough caused the strong convective weather. The radar echo analysis showed that the radar echo in the process belonged to the typical multi-monomer windstorm echo, and the strong echo zone was in the forefront of echo. When the convection development was the strongest, the echo intensity reached 65 dBz, and the echo top height surpassed 11 km. As the development of windstorm monomer, the big-value zone of vertical liquid water content product had the jumping formation and disappearance. Moreover, there was obvious weak echo zone. The windstorm monomer moved to the southeast direction as the precipitation system. In the right front of monomer moving direction, there was hook echo feature. The evolution characteristics of radial speed field at the different elevation angles before and after the hail weather occurrence were analyzed. It was found that the radial speed field had some premonitory variations before the hail weather occurrence. Doppler radar product was used to improve the initial field of MM5 model, which could improve the forecast effect in the certain degree and the accuracy of short-time forecast and nowcasting. [Conclusion] The research accumulated the experience for the short-term forecast and nowcasting work of strong convective weather in future.展开更多
Heavy rains occur in China frequently, which often bring us floods and serious disasters in the summer half-year. The meso-scale heavy rain parcels (MHRP) in the mid-latitude are usually developed in following cases:I...Heavy rains occur in China frequently, which often bring us floods and serious disasters in the summer half-year. The meso-scale heavy rain parcels (MHRP) in the mid-latitude are usually developed in following cases:I.By the approaching, meeting and / or overlapping of different weather systems, when two or more different rainfall systems are getting to conjugate, some MHRPs could be developed, such as: 1) a new cold/warm front or squall line approaches an old front or squall, even when the old one is somewhat decrepit; 2) at the places where two or more synoptic systems with different characteristics are meeting together, such as the meeting of tropical cyclone with the cold airs coming from the mid- and / or high-latitudes, or the low latitude vortex meeting with the westerly trough; 3) at the intersections of some different weather systems, such as the intersection of drylines, squall lines or fronts moving from different directions; and 4) by the overlapping of rainfall parcels produced continuously from a meso-generation centre.II.Resonance Effect and Tibetan Plateau Influence are two reasons why high frequency of heavy and torrential rains arround the meiyu front is discussed also.展开更多
利用海口多普勒雷达、海南省区域加密自动站和常规资料对2016年4月11日凌晨发生在海南岛北部近海和陆地的大范围雷暴大风过程进行天气学分析。结果表明:(1)这次雷暴大风过程发生在500 h Pa槽前、低空急流左前侧、低层切变线南侧、高空...利用海口多普勒雷达、海南省区域加密自动站和常规资料对2016年4月11日凌晨发生在海南岛北部近海和陆地的大范围雷暴大风过程进行天气学分析。结果表明:(1)这次雷暴大风过程发生在500 h Pa槽前、低空急流左前侧、低层切变线南侧、高空急流分流区下方和地面静止锋南侧的有利于对流发展的较大范围上升气流区域内;(2)对流风暴移动路径上的大气环境具有中等程度的条件不稳定、对流有效位能CAPE以及上干冷下暖湿的温-湿廓线垂直结构、强的深层垂直风切变,对流风暴形成后最终组织发展产生雷暴大风、大冰雹和短时强降水的多单体带状回波和弓形回波;(3)在多单体带状回波中镶嵌的风暴A和B各自发展成为具有中层径向辐合特征的超级单体,风暴B和C合并形成弓形回波,其中风暴C的中气旋加强成为弓形回波北部的气旋式中尺度涡旋;(4)阵风锋对对流风暴的正反馈作用、对流风暴前侧强劲的暖湿入流与风暴后侧径向风速相当的冷池出流,长时间倾斜依存的自组织结构及其与强的低层环境风垂直切变的相互作用,是多单体风暴和弓形回波长时间维持和加强的主要原因;(5)地面原来存在的β中尺度辐合切变线,对流风暴主体回波沿着海南岛北部近海东移等因素,有利于多单体带状回波和弓形回波的长时间维持。展开更多
利用新一代多普勒天气雷达资料及国家、区域自动站和常规高空地面资料,分析了2008-2013年河南省9次区域暴雨回波系统的形态、结构特征、移动特点和降水强度等,分析了区域暴雨过程中中γ尺度对流系统的降水特征。结果表明：1）河南区域...利用新一代多普勒天气雷达资料及国家、区域自动站和常规高空地面资料,分析了2008-2013年河南省9次区域暴雨回波系统的形态、结构特征、移动特点和降水强度等,分析了区域暴雨过程中中γ尺度对流系统的降水特征。结果表明：1）河南区域暴雨落区主要位于高空槽前和副高西北侧、中低层切变线之间、低涡东南侧、低空急流左前侧,以及地面倒槽或气旋顶部偏北到偏东气流中。2）从新一代雷达监测产品来看,河南省区域暴雨主要有积云降水、积层混合降水和层状云降水三种回波类型,其中混合降水包括以积云为主的混合降水和以层云为主的混合降水,是河南省区域暴雨的主要回波类型。3）降水强度与回波类型、结构特征、移动特点等均有关系,特别是≥50 mm/h的短时强降水与γ中尺度对流系统密切相关,强降水超级单体可造成局地50 mm/h以上的强降水,并多伴有雷暴大风、龙卷等剧烈对流天气。一般情况下,积云降水强度最大,混合降水次之,层云降水强度最小。综合分析来看,雨强与回波强度比与回波性质有更好的相关性。≥50 mm/h的强降水多由强降水超级单体和因辐合、气旋、后向传播等使回波加强、合并、发展旺盛的准静止状态的50~60 d Bz的强积云降水回波产生;≥20 mm/h强降水多由积层混合降水中≥45 d Bz的积云回波产生。10 mm/h以上的降水落区和≥40 d Bz的较强回波有很好的对应关系;〈40 d Bz的层云回波降水强度通常在10 mm/h以下。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.40206004)partly by the open foundation of Key Laboratory of Polar Science of Science of the State Oceanic Administration,China(Grant No.KP2007004).
文摘On small-meso scale, the sea ice dynamic characteristics are quite different from that on large scale. To model the sea ice dynamics on small-meso scale, a new elastic-viscous-plastic （EVP） constitutive model and a hybrid Lagrangian- Eulerian （HLE） numerical method are developed based on continuum theory. While a modified discrete element model （DEM） is introduced to model the ice cover at discrete state. With the EVP constitutive model, the numerical simulation for ice ridging in an idealized rectangular basin is carried out and the results are comparable with the analytical solution of jam theory. Adopting the HLE numerical model, the sea ice dynamic process is simulated in a vortex wind field. The furthering application of DEM is discussed in details for modeling the discrete distribution of sea ice. With this study, the mechanical and numerical models for sea ice dynamics can be improved with high precision and computational efficiency.
基金Supported by National Meteorological Bureau Program in 2011 (GY-HY201106003)
文摘[Objective]The aim was to analyze the mesoscale and small scale system that influenced the strong rainfall in Hunan from June 18 to 20 in 2010. [Method] By dint of regular observation material and rainfall in regional automatic station, TBB of FY-2C geostationary meteorological satellite, characteristics and causes of one heavy rainfall event in Hunan Province on 18-20 June 2010 were studied. [Result] The rainstorm happened under the southwest warm and wet torrent at the edge of subtropical high when the ground cold air intruded, which triggered the release of unstable energy. The water vapor from Bay of Bengal and South China Sea sent abundant water vapor to south China. The water vapor strengthened, which synchronized with the rainstorm. The ground mesoscale convergence line and the mesoscale low pressure intensified the rainstorm. Changes of pressure field reflected the changes of rainfall and indicated the location and movement of heavy rainfall. [Conclusion] The study provided theoretical basis to understand the rainstorm formation mechanism and improve disaster prevention capacity.
文摘[Objective] The research aimed to study the meso-scale characteristics of a hail process in Linyi area. [Method] By comprehensively using MICAPS conventional observation data, automatic encryption ground station, MM5 model product and Doppler weather radar data, a strong convective hail weather process which happened in Shandong Peninsula and southeast of Shandong on May 30, 2010 was analyzed. The circulation background and physical mechanism of strong convection weather occurrence, the features of meso- and micro-scale systems were discussed. Some occurrence and development rules of such weather were found. [Result] The strong convective weather was mainly affected by the cold vortex and translot. The high-altitude northwest airflow, low-level southwest airflow, dry and cold air at the high layer, warm and wet air at the low layer, forward-tilting trough caused the strong convective weather. The radar echo analysis showed that the radar echo in the process belonged to the typical multi-monomer windstorm echo, and the strong echo zone was in the forefront of echo. When the convection development was the strongest, the echo intensity reached 65 dBz, and the echo top height surpassed 11 km. As the development of windstorm monomer, the big-value zone of vertical liquid water content product had the jumping formation and disappearance. Moreover, there was obvious weak echo zone. The windstorm monomer moved to the southeast direction as the precipitation system. In the right front of monomer moving direction, there was hook echo feature. The evolution characteristics of radial speed field at the different elevation angles before and after the hail weather occurrence were analyzed. It was found that the radial speed field had some premonitory variations before the hail weather occurrence. Doppler radar product was used to improve the initial field of MM5 model, which could improve the forecast effect in the certain degree and the accuracy of short-time forecast and nowcasting. [Conclusion] The research accumulated the experience for the short-term forecast and nowcasting work of strong convective weather in future.
文摘Heavy rains occur in China frequently, which often bring us floods and serious disasters in the summer half-year. The meso-scale heavy rain parcels (MHRP) in the mid-latitude are usually developed in following cases:I.By the approaching, meeting and / or overlapping of different weather systems, when two or more different rainfall systems are getting to conjugate, some MHRPs could be developed, such as: 1) a new cold/warm front or squall line approaches an old front or squall, even when the old one is somewhat decrepit; 2) at the places where two or more synoptic systems with different characteristics are meeting together, such as the meeting of tropical cyclone with the cold airs coming from the mid- and / or high-latitudes, or the low latitude vortex meeting with the westerly trough; 3) at the intersections of some different weather systems, such as the intersection of drylines, squall lines or fronts moving from different directions; and 4) by the overlapping of rainfall parcels produced continuously from a meso-generation centre.II.Resonance Effect and Tibetan Plateau Influence are two reasons why high frequency of heavy and torrential rains arround the meiyu front is discussed also.
文摘利用海口多普勒雷达、海南省区域加密自动站和常规资料对2016年4月11日凌晨发生在海南岛北部近海和陆地的大范围雷暴大风过程进行天气学分析。结果表明:(1)这次雷暴大风过程发生在500 h Pa槽前、低空急流左前侧、低层切变线南侧、高空急流分流区下方和地面静止锋南侧的有利于对流发展的较大范围上升气流区域内;(2)对流风暴移动路径上的大气环境具有中等程度的条件不稳定、对流有效位能CAPE以及上干冷下暖湿的温-湿廓线垂直结构、强的深层垂直风切变,对流风暴形成后最终组织发展产生雷暴大风、大冰雹和短时强降水的多单体带状回波和弓形回波;(3)在多单体带状回波中镶嵌的风暴A和B各自发展成为具有中层径向辐合特征的超级单体,风暴B和C合并形成弓形回波,其中风暴C的中气旋加强成为弓形回波北部的气旋式中尺度涡旋;(4)阵风锋对对流风暴的正反馈作用、对流风暴前侧强劲的暖湿入流与风暴后侧径向风速相当的冷池出流,长时间倾斜依存的自组织结构及其与强的低层环境风垂直切变的相互作用,是多单体风暴和弓形回波长时间维持和加强的主要原因;(5)地面原来存在的β中尺度辐合切变线,对流风暴主体回波沿着海南岛北部近海东移等因素,有利于多单体带状回波和弓形回波的长时间维持。
文摘利用新一代多普勒天气雷达资料及国家、区域自动站和常规高空地面资料,分析了2008-2013年河南省9次区域暴雨回波系统的形态、结构特征、移动特点和降水强度等,分析了区域暴雨过程中中γ尺度对流系统的降水特征。结果表明：1）河南区域暴雨落区主要位于高空槽前和副高西北侧、中低层切变线之间、低涡东南侧、低空急流左前侧,以及地面倒槽或气旋顶部偏北到偏东气流中。2）从新一代雷达监测产品来看,河南省区域暴雨主要有积云降水、积层混合降水和层状云降水三种回波类型,其中混合降水包括以积云为主的混合降水和以层云为主的混合降水,是河南省区域暴雨的主要回波类型。3）降水强度与回波类型、结构特征、移动特点等均有关系,特别是≥50 mm/h的短时强降水与γ中尺度对流系统密切相关,强降水超级单体可造成局地50 mm/h以上的强降水,并多伴有雷暴大风、龙卷等剧烈对流天气。一般情况下,积云降水强度最大,混合降水次之,层云降水强度最小。综合分析来看,雨强与回波强度比与回波性质有更好的相关性。≥50 mm/h的强降水多由强降水超级单体和因辐合、气旋、后向传播等使回波加强、合并、发展旺盛的准静止状态的50~60 d Bz的强积云降水回波产生;≥20 mm/h强降水多由积层混合降水中≥45 d Bz的积云回波产生。10 mm/h以上的降水落区和≥40 d Bz的较强回波有很好的对应关系;〈40 d Bz的层云回波降水强度通常在10 mm/h以下。
