Effect of Baroclinicity on Vortex Axisymmetrization. Part Ⅰ:Barotropic Basic Vortex     

Melinda S.PENG  Jiayi PENG  Tim LI  Eric HENDRICKS 《大气科学进展》2014,31(6)

The barotropic and baroclinic disturbances axisymmetrized by the barotropic basic vortex are examined in an idealized modeling framework consisting of two layers. Using a Wentzel-Kramers-Brillouin approach, the radial propagation of a baroclinic disturbance is shown to be slower than a barotropic disturbance, resulting in a slower linear axisymmetrization for baroclinic disturbances. The slower-propagating baroclinic waves also cause more baroclinic asymmetric kinetic energy to be transferred directly to the barotropic symmetric vortex than from barotropic disturbances, resulting in a faster axisymmetrization process in the nonlinear baroclinic wave case than in the nonlinear barotropic wave case.  相似文献   

福建省枇杷气象灾害综合风险评估   总被引：1，自引：1，他引：0       下载免费PDF全文

陈家金  李丽纯  林晶  王加义  郑东旗  黄川容 《应用气象学报》2014,25(2):232-241

通过辨识影响福建省枇杷生长发育和产量的主要致灾因子,分析枇杷对气象灾害的敏感性和暴露性,考虑种植区的防灾减灾能力,构建出枇杷气象灾害综合风险评估指标体系,利用枇杷种植区1971—2011年气象资料,1992—2011年枇杷种植面积、产量及其他社会经济资料,采用层次分析法和熵权系数法融合方法计算各风险指标的权重及各评估单元的风险指数,进而构建枇杷气象灾害的综合风险评估模型,应用GIS技术制作出风险精细区划图,评估枇杷气象灾害的综合风险。结果表明:致灾危险性对综合风险的影响最大,起主要作用;重度以上的综合风险主要分布在福建省5个主要山脉的中高海拔山区以及枇杷种植面积大的莆田市、福清市、云霄县,轻度综合风险区主要分布在中南部沿海县市的低海拔种植区 (除种植大县和东山县外),其余种植区的综合风险属中度。  相似文献   

Shell sand properties and vegetative distribution on shell ridges of the Southwestern Coast of Bohai Bay     

Wenjun Xie  Yanyun Zhao  Zhidong Zhang  Qing Liu  Jiangbao Xia  Jingkuan Sun  Jiayi Tian  Tongqiu Sun 《Environmental Earth Sciences》2012,67(5):1357-1362

Little information is available about shell ridge ecosystems. Vegetative distribution and shell sand properties were investigated on a shell ridge in the Binzhou National Shell Ridge and Wetland Nature Reserve. 21 plant species were observed in the study area and, according to the Shannon?CWeiner Index and species evenness, vegetative cover, and abundance varied significantly at different sites (P?<?0.05). Sand percent, dissolved organic C, total N, and available N concentrations were significantly higher in the upper layers, while total and available P and K concentrations were significantly higher in the lower profile. Plant species were divided into three groups based on canonical correspondence analysis. Group A included 10 plant species, and was well correlated with high available nutrient concentrations (dissolved organic C, and available N, P, and K) and sand moisture. Groups B and C were well correlated with total K, P and salinity. Thus shell sand properties affected the spatial distribution of vegetation in the study area. Due to the coarse texture, salinity was less than 0.4% and much lower than in adjacent soils. Ten salt-sensitive plant species were found, accounting for 48% of the total plant species. Shell sand is therefore imperative to shell ridge ecosystem sustainability, and shell sand mining should be prohibited in the area.  相似文献