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El Nino事件与中国东部气温异常 总被引：5，自引：0，他引：5
本文进行的多年历史资料的分析表明,中国东部地区的气温异常同El Nino事件有密切的关系 在El Nino年夏季中国东北及附近地区气温多比常年偏低,而在反El Nino年夏季那里气温多出现高温异常。在El Nino年冬季,中国东部广大地区气温比常年偏高:反El Nino年冬季,中国东部广大地区气温比常年编低。中国东部地区的温度异常同El Nino所造成的大气环流异常的关系,本文亦作了分析研究。 中国东部地区冬半年气温的持续编低同El Nino事件的发生有密切关系,表明东亚地区持续的强高空槽活动(寒潮活动)可能是El Nino事件发生的重要触发机制。 相似文献
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根据1800-1989年(110年)的资料,分析研究了新加坡地区月平均和年平均降雨量的一些特征。主要结论是:新加坡年平均降雨量存在准2-6年和18年的周期振荡;亚洲季风以及ENSO对新加坡降雨量有明显的影响。新加坡年雨量的谷值出现在西南季风期而峰值在东北季风期。在El Nino年,新加坡降雨量多为负距平;而在反El Nino年,新加坡降雨量多为正距平。 相似文献
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El Nio事件与番禺降水的相关性分析 总被引：9，自引：9，他引：0
采用X^2检验方法,统计分析番禺地面气象站1961～2006年的逐月降水资料与El Nino现象的关系。结果表明：两类El Nino事件与番禺年降水量有密切关系,Ⅰ类El Nino事件与番禺年降水量呈强的正相关,降水增加量平均为26．63％,而Ⅱ类El Nino事件与番禺年降水量呈负相关,降水减少量平均为11．46％。从季节分布来看,两类El Nino事件对锋面降水和季风过渡季节降水影响较小,而对汛期降水影响较大。两类事件对降水影响的差异主要通过西太平洋副高脊线位置的差异表现出来：Ⅰ类El Nino事件影响年,4～6月副高脊线位置较常年偏南,7、8月偏北;Ⅱ类El Nino事件影响年,4～6月副高脊线位置较常年偏北,7、8月偏南。 相似文献
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两类ENSO对我国华南地区冬季降水的不同影响 总被引：5，自引：0，他引：5
El Nino Modoki是近年发现的赤道太平洋海温异常分布的新特征,主要表现为热带太平洋海温异常为纬向"三极型"分布,与传统的El Nino的"偶极型"分布显著不同。本文利用1979～2010年冬季降水观测资料以及NCEP/NCAR再分析月平均资料,分析了El Nino和El Nino Modoki对我国华南地区冬季降水的不同影响。结果表明,El Nino年冬季,西太平洋副热带高压偏强偏南,我国华南地区受其西侧异常西南风影响,获得充足的水汽供应。另外,高层抽吸作用增强,上升运动加强,对流发展,降水偏多;而El Nino Modoki年冬季,西太平洋副热带高压位置偏北,我国华南地区受高压脊控制。华南地区高层抽吸作用减弱,上升运动减弱,对流减弱,并且水汽供应不足,导致降水偏少。 相似文献
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通过合成的El NiNo和La NiNa的分析发现,一般一个El Nino或La Nina事件大致可以分成爆发前的冬季、发展期的夏季、盛期时的冬季和衰亡期的夏季四个阶段.在此基础上利用NCEP再分析环流资料和中国降水资料分析了东亚冬、夏季风对E1 Nino和LaNina的响应,结果发现,E1 Nino和La Nina事件显著地影响了东亚冬、夏季风的循环.E1Nino爆发前的冬季在东亚地区往往有异常强的北风;El Nino发展期的夏季,西太平洋副热带高压偏弱,同时影响我国的西南气流偏弱,从而江淮地区和南方沿海地区多雨,长江中游和华北地区少雨;E1 Nino盛期的冬季东亚地区则出现异常的南风;而E1 Nino衰亡期的夏季,西太平洋副热带高压偏强,同时影响我国的西南气流偏强,从而江淮地区少雨,华北、东北以及洞庭湖、鄱阳湖地区多雨.La Nina对东亚冬、夏季风循环的影响则与El Nino大致相反,但它的影响不如El ino的影响显著.对强、弱东亚冬季风后的夏季中国降水异常的分析则表明,正是由于与El Nino或La Nina事件有关的海温异常对东亚冬、夏季风循环的影响才导致了东亚冬季风与随后的夏季风存在着紧密的联系;当冬季风异常不是由与ElNiNino或La Nina事件有关的海温异常所引起时,两者之间就缺少显著的联系. 相似文献
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通过合成的El NiNo和La NiNa的分析发现,一般一个El Nino或La Nina事件大致可以分成爆发前的冬季、发展期的夏季、盛期时的冬季和衰亡期的夏季四个阶段.在此基础上利用NCEP再分析环流资料和中国降水资料分析了东亚冬、夏季风对E1 Nino和LaNina的响应,结果发现,E1 Nino和La Nina事件显著地影响了东亚冬、夏季风的循环.E1Nino爆发前的冬季在东亚地区往往有异常强的北风;El Nino发展期的夏季,西太平洋副热带高压偏弱,同时影响我国的西南气流偏弱,从而江淮地区和南方沿海地区多雨,长江中游和华北地区少雨;E1 Nino盛期的冬季东亚地区则出现异常的南风;而E1 Nino衰亡期的夏季,西太平洋副热带高压偏强,同时影响我国的西南气流偏强,从而江淮地区少雨,华北、东北以及洞庭湖、鄱阳湖地区多雨.La Nina对东亚冬、夏季风循环的影响则与El Nino大致相反,但它的影响不如El ino的影响显著.对强、弱东亚冬季风后的夏季中国降水异常的分析则表明,正是由于与El Nino或La Nina事件有关的海温异常对东亚冬、夏季风循环的影响才导致了东亚冬季风与随后的夏季风存在着紧密的联系;当冬季风异常不是由与ElNiNino或La Nina事件有关的海温异常所引起时,两者之间就缺少显著的联系. 相似文献
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利用SST资料对西太平洋暖池海温异常年进行划分,通过对异常年850 hPa、200 hPa矢量风场进行合成分析后发现:在西太平洋暖池夏季暖异常年,副热带夏季风和副热带季风经圈环流得到加强,热带西南季风得到削弱;在暖池夏季冷异常年,热带西南季风和热带季风经圈环流得到了加强,副热带夏季风得到削弱.在暖池冬季暖异常年,东亚冬季风、东亚和印尼一北澳冬季风(北半球)经向垂直环流得到削弱;在暖池冬季冷异常年,东亚冬季风、东亚和印尼一北澳冬季风(北半球)经向垂直环流得到加强. 相似文献
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冬季赤道西太平洋环流状况与后期亚洲季风 总被引：4，自引：0，他引：4
基于月平均NCEP再分析资料(1958～1997年)以及中国336个台站月降水总量(195l～1994年),通过合成、相关以及统计显著性检验方法,研究了赤道西太平洋区域冬季环流状况与后期春夏季亚洲(东亚和南亚)季风环流变化的关系.研究结果表明,冬季赤道西太平洋环流状况对后期南亚季风和东亚季风以及我国夏季降水均有显著的滞后影响.冬季赤道西太平洋海域海平面气压偏高(低),对应反气旋(气旋)性环流异常,致使后期东亚和南亚夏季风均偏弱(强)以及我国长江流域夏季降水偏多(少),揭示了实施这种滞后影响的一般特征. 相似文献
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The purpose of this study was to develop a diffusion model for a continuous point source which takes into account the increase
of wind speed with height, and to compare this model with short-range diffusion experiments. The main problem was to find
a good expression for the vertical diffusion coefficient. It turned out that good agreement between theory and experiment
could only be obtained by introducing a settling speed W for the tracer combined with a conventional expression for the vertical diffusion (K(Z) = K
0Z1−p). An empirical relation was found between K
0 and τ
vU and between W and bar
σ
vU2. 相似文献
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The effect of topographical slope angle and atmospheric stratification on turbulence intensities in the unstably stratified surface layer have been parameterized using observations obtained from a three-dimensional sonic anemometer installed at 8 m height above the ground at the Seoul National University (SNU) campus site in Korea for the years 1999–2001. Winds obtained from the sonic anemometer are analyzed according to the mean wind direction, since the topographical slope angle changes significantly along the azimuthal direction. The effects of the topographical slope angle and atmospheric stratification on surface-layer turbulence intensity are examined with these data. It is found that both the friction velocity and the variance for each component of wind normalized by the mean wind speed decrease with increase of the topographical slope angle, having a maximum decreasing rate at very unstable stratification. The decreasing rate of the normalized friction velocity (u
* /U) is found to be much larger than that of the turbulence intensity of each wind component due to the reduction of wind shear with increase in slope angle under unstable stratification. The decreasing rate of the w component of turbulence intensity (σ
w
/U) is the smallest over the downslope surface whereas that of the u component (σ
u
/U) has a minimum over the upslope surface. Consequently, σ
w
/u
* has a maximum increasing rate with increase in slope angle for the downslope wind, whereas σ
u
/u
* has its maximum for the upslope wind. The sloping terrain is found to reduce both the friction velocity and turbulence intensity compared with those on a flat surface. However, the reduction of the friction velocity over the sloping terrain is larger than that of the turbulence intensity, thereby enhancing the turbulence intensity normalized by the friction velocity over sloping terrain compared with that over a flat surface. 相似文献
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冬季西风环流指数的变率及其与北半球温度变化的关系研究 总被引：17，自引：2，他引：17
用H40°N-H65°N即40°N和65°N纬圈平均位势高度的差来定义西风指数,可以很好地反映温带地区西风的强弱。西风环流强的年份,北半球气温通常偏高,主要是中纬度大陆变暖明显,这可能与中高纬度西风强时,向北的经向热量输送也加强有关。在长期变化的趋势上,1950年代以前北半球偏暖时期的指数偏低,而偏冷时期的指数偏高。但近30多年来,伴随全球加速变暖,西风指数也持续加强,这是否与温室效应的加强有关还有待深入研究。 相似文献
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Surface measurements of cloud condensation nuclei (CCN) number concentration (cm−3) are presented for unmodified marine air and for polluted air at Mace Head, for the years 1994 and 1995. The CCN number concentration active at 0.5% supersaturation is found to be approximately log-normal for marine and polluted air at the site. Values of geometric mean, median and arithmetic mean of CCN number concentration (cm−3) for marine air are in the range 124–135, 140–150 and 130–157 for the two years of data. Analysis of CCN number concentration for high wind speed, U, up to 20 m s−1 show enhanced CCN production for U in excess of about 10–12 m s−1. Approximately 7% increase in CCN per 1 m s−1 increase in wind speed is found, up to 17 m s−1. A relationship of the form log10CCN=a+bU is obtained for the periods March 1994 and January, February 1995 for marine air yielding values a of 1.70; 1.90 and b of 0.035 for both periods. 相似文献
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THE APPROACH TO REMOTE SENSING OF WATER VAPOR BASED ON GPS AND LINEAR REGRESSION Tm IN EASTERN REGION OF CHINA 
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下载免费PDF全文 The approach to remote sensing of water vapor by using global positioning systems(GPS) isdiscussed.In order to retrieve the vertical integrated water vapor(IWV) or the precipitable water(PW),the weighted "mean temperature" of the atmosphere,Tm would be estimated to the specificarea and season.Tm depends on surface temperature,tropospheric temperature profile,and thevertical distribution of water vapor.The surface temperature dependence is borne out by acomparison of Tm and the values of surface temperature Ts using radiosonde profiles of BeijingStation(No.54511) throughout 1992.The analysis of radiosonde profiles spanning a one-yearinterval(1992) from sites in eastern region of China with a latitude range of 20-50°N and alongitude range of 100-130°E yields the coefficients a and b of a linear regression equation Tm=a+bTs. 相似文献
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The impact of different vertical diffusion schemes in a three-dimensional oil spill model in the Bohai Sea 总被引：2，自引：0，他引：2
Vertical transport is critical to the movement of oil spills in seawater. Breaking waves play an important role by developing a well-defined mixing layer in the upper part of the water column. A three-dimensional （3-D） Lagrangian random walk oil spill model was used here to study the influence of sea surface waves on the vertical turbulence movement of oil particles. Three vertical diffusion schemes were utilized in the model to compare their impact on oil dispersion and transportation. The first scheme calculated the vertical eddy viscosity semi-empirically. In the second scheme, the vertical diffusion coefficient was obtained directly from an Eulerian hydrodynamic model （Princeton Ocean Model, POM2k） while considering wave- caused turbulence. The third scheme was formulated by solving the Langevin equation. The trajectories, percentages of oil particles intruding into water, and the vertical distribution structures of oil particles were analyzed for a series of numerical experiments with different wind magnitudes. The results showed that the different vertical diffusion schemes could generate different horizontal trajectories and spatial distributions of oil spills on the sea surface. The vertical diffusion schemes caused different water-intruding and resurfacing oil particle behaviors, leading to different horizontal transport of oil particles at the surface and subsurface of the ocean. The vertical diffusion schemes were also applied to a realistic oil spill simulation, and these results were compared to satellite observations. All three schemes yielded acceptable results, and those of the third scheme most closely simulated the observed data. 相似文献
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S. S. Zilitinkevich 《Boundary-Layer Meteorology》1978,14(1):29-33
The surface drift current speed and direction are defined using the resistance laws for turbulent Ekman boundary layers. Stratification conditions that coincide in the atmospheric and oceanic boundary layers yield approximate formulas whereby the drift current and geostrophic wind directions coincide and the geostrophic wind factor k is equal to the square root of the air and water density ratio. The theoretical estimates of k are compared with available experimental data. 相似文献
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Summary ?We have investigated the effects of shear and sharp gradients in static stability and demonstrated how a mountain wave and
its associated surface winds can be strongly influenced. Linear theory for two-dimensional, nonrotating stratified flow over
an isolated mountain ridge with positive shear and constant static stability shows that the horizontal wind speeds on both
the lee and upslope surfaces are suppressed by positive shear. The critical F(=U/Nh where U is the basic wind speed, N the Brunt-Vaisala frequency, and h the mountain height) for the occurrence of wave breaking decreases when the strength of the positive shear increases, while
the location for the wave-induced critical level is higher in cases with larger positive shear. The linear theory is then
verified by a series of systematic nonlinear numerical experiments. Four different flow regimes are found for positive shear
flow over a two-dimensional mountain. The values of critical F which separate the flow regimes are lower when the strength of the positive shear is larger. The location of stagnation aloft
from numerical simulations is found to be quite consistent with those predicted by linear theory.
We calculate the strongest horizontal wind speed on the lee surface (U
max), the smallest horizontal wind speed on the upslope surface (U
min), the reflection (Ref), and the transmission (Tran) coefficients for different combinations of the stability ratio between
the upper and lower layers (i.e. and z
1 (interface height) in a two-layer atmosphere from linear analytical solutions. Both Ref and Tran are found to be functions
of log() but not the interface height (z
1). Ref is larger when is much different from 1, no matter whether it is larger or smaller than 1. However, Tran decreases when log() increases and approaches 0 when log() is large. The magnitude of the largest U
max (smallest U
min) increases (decreases) as the absolute value of log() increases. It is found that the largest U
max occurs when the nondimensional z
1 is near for cases with a less stable upper layer or when z
1 is near for cases with a more stable upper layer. These results are confirmed by nonlinear numerical simulations. We find that linear
theory is very useful in qualitative analysis of the possibility of high-drag state for different stability profiles. The
location of stagnation aloft in a two-layer atmosphere from numerical simulations agrees very well with those predicted by
linear theory.
The above findings are applied to investigate the Boulder severe downslope windstorm of 11 January 1972. We find that the
windstorm cannot develop if the near mountain-top inversion is located at a higher altitude (e.g., km). However, if there exists a less stable layer right below the tropopause, the windstorm can develop in the absence of
a low-level inversion. These results indicate the importance of partial reflection due to the structured atmosphere in influencing
the possibility of severe downslope windstorms, although partial reflection may not be the responsible mechanism for the generation
of windstorms.
Received September 25, 1999/Revised February 9, 2000 相似文献