排序方式: 共有71条查询结果,搜索用时 15 毫秒
41.
对澳门近百年的地表气温和降水等观测资料进行了统计分析和小波变换计算。结果表明,年/季节平均气温和年降雨量等气候变量的变化普遍存在2~5年周期的显著振荡,同时,振荡在时间域上有明显的局部性。年平均气温的周期约为60年的振荡与Atlantic multidecadal oscillation(AMO)密切相关,两者的位相相当一致。季节平均气温的变化存在明显的季节性差异,夏季和冬季分别有周期约为30年和60年的振荡,它们分别与Pacific decadal oscillation(PDO)和AMO的变化显著相关。前汛期降雨量和年蒸发量也有周期为几十年的年代际变化。 相似文献
42.
43.
With the hourly data of Air Pollution Index (API) by Hong Kong Environmental Protection
Department (HKEPD) during the 6 years of 2000 - 2005 and NCEP / NCAR reanalysis data of 2.5° ×
2.5° wind and pressure fields, the characteristics of API in Hong Kong area and the impacts of typical
weather characteristics on the air pollution in Hong Kong have been studied. The results are shown as
follows. (1) The API exhibits obvious seasonal variability as the number of air pollution days increases by
the year. For most of the local monitoring stations, it is the most from January to March, a little less from
July to September and the least from April to June. (2) There are four typical types of weather situations
that are responsible for the air pollution in Hong Kong: tropical cyclones, continental cold highs,
transformed highs that have moved out to sea and low pressure troughs. 相似文献
44.
初夏南海海温对华南降水影响的数值模拟 总被引:8,自引:0,他引:8
本文采用P-σ五层原始方程模式以气候统计分析结果为依据就6月份南海海温对华南地区降水的影响进行了数值模拟.试验结果表明,由于南海的海表温度增暖,华南地区低层有水汽辐合,并有较强的上升运动配置,使该地区降水增加.同时东亚季风环流也随之加强,整个东亚高、低层都呈现有利于华南地区降水增加的环流形势.在低层,由于南海海温增暖,使越过中南半岛的西南季风和110°E附近的越赤道气流都得到加强,从而增加了向南海及华南地区的水汽输送.在高层,南亚高压呈“东部型”,在我国大陆上空得到加强. 相似文献
45.
台风Fitow降雨的数值预报试验 总被引:11,自引:0,他引:11
用MM5对热带气旋Fitow(2001)的登陆过程进行了成功的预报,特别是对台风暴雨中心的位置和降雨量的预报与实况相当吻合。敏感性试验表明,华南地形对本次台风登陆过程中心气压和位置的变化没有明显的影响,但对台风低压北侧还是有一定的阻挡填塞作用,尤其是对24h累计的降水量有明显的增幅作用,而华南地形的这些影响主要是由南岭山脉所造成的。由于南岭山脉的阻挡,使南来的暖湿气流强迫抬升,促进了对流活动和降水系统的发展,最终造成台风降雨量明显加强,其增幅达30%。 相似文献
46.
热带气旋"黄蜂"动热力特征演变的模拟分析 总被引:9,自引:1,他引:8
以"中国登陆台风试验"项目的目标热带气旋"黄蜂"为对象,用高分辨数值模式成功模拟了其近海加强和登陆减弱的过程,从定量和时间演化角度细致分析了热带气旋(TC)各阶段的动、热力特征,包括对流加热特性、温湿结构、稳定度、涡散度、垂直运动、垂直环流、水平环流等基本动、热力因子的时空结构特征,揭示了该热带气旋的大量结构特点,如对流加热的强盛和非对称性、强热带风暴的无眼结构、低层的东暖西冷结构、涡度的准圆形对称结构、东/西侧环流正/斜压性的差异、低层辐合和上升运动的准周期振荡等等.这些结构特征的揭示对深入细致地研究和认识南海热带气旋的特点和演变机理具有重要学术意义. 相似文献
47.
用QuikSCAT资料分析"黄蜂"登陆前后近地层风场的分布特征 总被引:7,自引:4,他引:3
利用QuikSCAT资料对"黄蜂"近地层风场分布的演变特征进行了诊断分析.并采用了离散余弦转换(DCT)对其方差的波谱结构进行了讨论.结果表明台风近地层风场分布具有明显的不对称性,其方差大部分产生于波数1和2的气流中,并且与波的方向有关.当台风沿纬向西移时,有两个纬向排列的波谱中心,主要是纬向波数2和经向波数1的气流;而当台风沿径向北上时,有两个经向排列的波谱中心,主要是纬向波数1和经向波数2的气流.波数1的气流对切向风的方差做主要贡献,波数2的气流对径向风的方差做主要贡献.不对称性分布的特征随大尺度环境场和台风自转气旋环流的改变而改变.当台风靠近大陆时台风大风出现的在台风前进方向前沿,类似于陈联寿等分析的第二类台风大风模式,在左前方是西北偏北大风,在右前方是东南大风. 相似文献
48.
EFFECTS OF CONDENSATION HEATING AND SURFACE FLUXES ON THE DEVELOPMENT OF A SOUTH CHINA MESOSCALE CONVECTIVE SYSTEM (MCS) 总被引:1,自引:2,他引:1
A sensitive numerical simulation study is carried out to investigate the effects of condensation
heating and surface fluxes on the development of a South China MCS that occurred during 23 – 24 May 1998.
The results reveal the following: (1) Condensation heating plays an important role in the development of MCS. In
every different stage, without condensation heating, MCS precipitation is significantly reduced, and quickly
dissipates. (2) Condensation heating demonstrates most importantly during the early development stages of MCS
vortex; as the vortex develops stronger, the condensation heating effects reduces. (3) By affecting the MCS
development processes, condensation heating also influences the formation of MCS mesoscale environment
structure features such as low-level jet (mLLJ), upper-level divergence. (4) By changing the antecedent
environmental circulation, the surface fluxes also play an important role in the development of MCS. Because of
the surface heating, pressure declines over the heavy rainfall and MCS happening regions, which results in the
intensification of southerly flows from the ocean along the South China coastline areas, and leads to the
enhancement of horizontal convergence and increase of vapor amount in the lower layer. All of these make the
atmosphere more unstable and more favorable for the convection. 相似文献
49.
With PSU/NCAR nonhydrostatic mesoscale model MM5, the rainfall process of tropical storm
Fitow(0114) is simulated for 00:00 UTC 31 Aug. – 00:00 UTC 2 Sept. 2001. Mesoscale separation is performed
on the results with the filtering scheme. Analyses show that the MM5 model well reproduced the position and
intensity of heavy rain. Mesoscale characteristics of heavy rain were well represented in rainfall time scale,
rainfall area, stream field and divergence at lower and upper levels. The interaction between inverted typhoon
troughs and the mesoscale systems lead to heavy rain occurrence. The distribution of divergence fields at lower
and upper levels can have a kind of indication for the rainfall. Heavy rains are closely associated with topography
and land-sea distribution in South China. Weak instability is favorable to the generation of heavy rain. 相似文献
50.
华南地区网格化在路机动车污染排放量估算与分析 总被引:8,自引:0,他引:8
在机动车数据的基础上,利用SMOKE模式估算了华南地区在路机动车污染物排放量,得到了用于空气质量数值模拟的网格化机动车排放源数据。估算结果显示机动车排放源主要分布在珠江三角洲和华南沿海地区,其中珠江三角洲排放量最大,且在深圳香港、广州、珠海澳门三个中心城市区分别出现了三个机动车排放中心,这三个中心与区域经济发达程度有较好的对应。分析还表明,快速增长的摩托车和小汽车数量对机动车排放总量的影响很大,是造成华南城市空气质量恶化的重要因素。 相似文献