排序方式： 共有9条查询结果，搜索用时 15 毫秒
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强对流天气短时临近预报系统（Severe Weather Automatic Nowcasting,SWAN）是面向短时临近监测、分析、预报、预警制作等功能为一体的业务平台。SWAN2.0基于MICAPS4（Meteorological Information Comprehensive Analysis and Processing System Version 4.0,人机交互气象信息处理和天气预报制作系统）二次开发框架,采用C/S架构,服务器部署在省级,负责收集数据,运算SWAN产品;客户端部署在气象台站,实现具体的预报业务,并形成算法二次开发接口。SWAN2.0新增了三维变分风场反演、基于分雨团技术的雷达降水估测、冰雹识别等方法,实现了算法管理、产品生成、分析处理、资料检索显示、实时监控报警、预警产品制作等功能。SWAN2.0业务系统已在全国试用,在强对流天气监测、分析和短时临近预报预警中发挥了重要作用。 相似文献
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台风灿鸿造成浙江东北部大暴雨地形作用的数值模拟研究 总被引：4，自引：3，他引：1
利用中尺度非静力数值模式WRF V3.6.1对台风灿鸿(1509)进行了高分辨率数值模拟,模式较好地再现了台风灿鸿的发展演变过程和在浙江东北部产生的强降水。观测资料显示台风接近浙江期间,在东北气流下,浙东北地形的摩擦辐合及抬升作用使得大量的对流云团汇集在台风西北侧,对流系统活跃,是浙江东北部产生强降水的重要原因。控制试验也模拟出了在台风接近陆地时,内核区西北侧存在有组织的、切向分布的小尺度对流系统,由地形强迫产生的降雨量和地形走向一致,迎风坡降雨量增加。通过升降地形,改变土地类型和将杭州湾水体用陆地替换等敏感性试验发现:(1)地形的影响对台风降雨量的增幅最为明显。通过降低地形,台风西北侧小尺度雨带明显减弱,浙江东北地区降水也明显减少。可见地形会影响这些中小尺度系统的结构和演变,引起降水异常变化。(2)大暴雨期间,台风一直维持较强的对称性,具有典型的眼墙和暖心结构。 相似文献
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用支持向量机方法做登陆热带气旋站点大风预报 总被引：2，自引：0，他引：2
将支持向量机（SVM）回归方法应用于在登陆热带气旋影响下,每天00、06、12、18 UTC 4时次2分钟平均的站点风速预报。从2002-2007年热带气旋本身强度、站点地形情况和站点附近高低空环境场要素,设计相关因子,建立了4种预报模式,其中模式4的风速拟合误差的标准差为1.591 m·s~（-1）。用2008年8个登录热带气旋做独立样本检验,预报风速与实际风速的平均绝对值误差为1.750 m·s~（-1）,标准差为2.367 m·s~（-1）。结果表明,在适当的样本截取和预报因子选取后,SVM方法建模的风速预报48小时内效果较好。 相似文献
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A minimal three-dimensional hurricane model formulated on an \(f\) -plane is used to investigate the asymmetries that develop when a model storm is subjected to ambient vertical wind shear. The asymmetries that form in the moist version of the model have a different structure to those that form in a dry version. In the moist case, there are two competing factors that influence the inner-core asymmetries: vertical wind shear and frictional convergence in the boundary layer. We show that the relative importance of these factors is different in the different stages of vortex evolution and different also in the core region compared with the outer region of the vortex. In the developing stage, the patterns of vertical velocity and temperature deviation above the boundary layer are primarily determined by the shear. When saturation occurs in the core region, the vortex rapidly intensifies and the upper and lower portions of the vortex become strongly coupled so that there is little tilt of the core region. In the mature stage, ascent associated with frictional convergence in the core tends to dominate the vertical motion field induced by the shear, but there are individual times when the patterns of ascent at the top of the boundary layer and at the upper level differ significantly. These times coincide mostly with fluctuations in the vortex track, which, in turn, must be influenced by asymmetries in the horizontal flow in the vortex. Even though the inner core of the vortex becomes upright with the onset of deep moist convection, the outer regions continue to have a significant tilt. Outside the core region, the asymmetries in the pattern of vertical motion above the boundary layer are associated primarily with the tilt of the outer vortex. 相似文献
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宁波市台风灾情评估和基于层次分析法的风险评估 总被引：6，自引：2，他引：6
筛选了1956—2016年间对宁波地区影响大、具有较完整灾情记录的台风个例30个,分析了台风灾情特征,并进行灾情评估;利用模糊算法和层次分析法,建立宁波地区台风风险评估模型。结果表明:近年来台风导致的死亡人数、倒塌房屋数量、水利和农作物受灾呈下降趋势;但是经济损失越来越大,浙江登陆台风造成养殖业的损失也有增大趋势。实际灾情指数(ADI)达到1级特重的台风有4个,达到2级(严重)及以上的有9个,ADI总体呈减小趋势。风险评估指数(RAI)与实际灾情指数(ADI)的相关系数为0.78,二者等级的一致率为73%;不一致的样本中,2000年之前风险评估等级小于灾情等级,2000年之后风险评估等级大于灾情等级。风险评估指数RAI和直接经济损失率的相关系数为0.7。业务中,可根据风险评估模型计算即将影响台风的RAI,利用直接经济损失率与RAI的拟合方程或者相近RAI的历史台风,估算其可能造成的经济损失。 相似文献
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It has long been known that incipient tropical cyclones (TCs) always occur in
synoptic-scale disturbances or tropical cyclogenesis precursors, and the disturbances can
intensify only within a limited area during tropical cyclogenesis. An observational analysis
of five tropical cyclogenesis events over the western North Pacific during 11 August to 10
September 2004 is conducted to demonstrate the role of synoptic-scale disturbances in
establishing a limited area of low-deformation vorticity for tropical cyclogenesis.
The analysis of the five tropical cyclogenesis events shows that synoptic-scale tropical
cyclogenesis precursors provide a region of low-deformation vorticity, which is measured with
large positive values of the Okubo-Weiss (OW) parameter. The OW concentrated areas are within
the tropical cyclogenesis precursors with a radius of about 400-500 km and can be found as
early as 72 hours prior to the formation of the tropical depression. When the TCs reached the
tropical storm intensity, the concentrated OW is confined to an area of 200-300 radius and the
storm centers are coincident with the centers of the maximum OW. This study indicates that the
tropical cyclogenesis occurs in the low-deformation 18-72 hours prior to the formation of
tropical depressions, suggesting the importance of low-deformation vorticity in pre-existent
synoptic-scale disturbances. Although the Rossby radius of deformation is reduced in TC
genesis precedes, the reduction does not sufficiently make effective conversion of convective
heating into kinetic energy within the low-deformation area. Further analysis indicates that
the initial development of four of the five disturbances is coupled with the counterclockwise
circulation of the mixed Rossby-Gravity (MRG) wave. 相似文献
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基于2010—2014年ASCAT反演风速、华东沿海14个浮标站和浙江沿海249个自动气象站资料,对华东沿海ASCAT反演风速进行检验和订正。研究表明:站点ASCAT风速误差不仅与离岸距离相关,而且与站点周围地形有关,误差较大的5个浮标站均位于舟山群岛附近海区,平均偏大4.79 m·s-1,其他海区浮标站的ASCAT反演风速平均偏差仅为0.46 m·s-1。ASCAT反演风速与浮标站风速的线性回归可有效减小反演风速误差,订正后误差大幅减小,误差越大的站点订正效果越好。相距160 km内的浮标站点间风速误差呈正相关,且站点间距越小,误差正相关越明显。考虑带影响半径的反距离权重,采用邻站方程订正法和邻站误差订正法分别对华东沿海ASCAT反演风速进行订正,均能明显减小平均偏差和均方根误差,两种方法订正效果接近,即两种方法均有较好的订正效果,可用于实际业务。 相似文献
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