台风麦莎登陆后粘性摩擦对正压特征波动的影响     

沈新勇  刘佳  秦南南  冯琎 《大气科学》2013,37(6):1219-1234

本文推导出柱坐标系下含有粘性摩擦项的正压方程组。选取2005年台风麦莎登陆浙江过程中的8月6日15时的WRF(Weather Research and Forecasting)模式输出资料,利用数值差分方法对该正压方程组求特征波解,分析粘性摩擦对台风麦莎内部正压特征波动的影响。结果表明,重力惯性外波在粘性摩擦的影响下,最不稳定波的波数为45左右,波动在摩擦的影响下衰减,波动沿逆时针传播,在半径1000 km处,1波波速为47.43 m/s,在半径r>800 km的范围内,径向风分量扰动加大,辐合辐散运动增强;而摩擦影响下的涡旋Rossby波,2波最不稳定,波动增长率减小,在半径r=200 km处波动相速度为4.282~29.172 m/s,扰动涡度大值区范围减小,涡旋Rossby波的波动区域沿着径向向台风中心收缩。分析包含所有波动时,考虑摩擦后,最不稳定波数在45左右且波动衰减,1波波速在r=1000 km处(外螺旋雨带)为26.374 m/s;在半径r=200 km(内螺旋雨带)为5.275 m/s,考虑径向基本气流后,最不稳定波的波数保持不变,半径r=1000 km处的波速增加为30.324 m/s,r=200 km(内螺旋雨带)处波速为6.065 m/s,摩擦使得径向风分量扰动明显增大,辐合辐散运动加强。  相似文献   

Cross-equatorial structures of equatorially trapped nonlinear Rossby waves     

《Dynamics of Atmospheres and Oceans》2013

Analysis of the Sea Surface Height (SSH) from satellite altimeters has shown that equatorially trapped Rossby waves exhibit asymmetric cross-equatorial structures; their northern extrema are much larger in magnitude than their southern counterparts. Such asymmetry is inconsistent with the classical theory for the first baroclinic, first meridional equatorially trapped Rossby mode, which predicts that SSH and zonal velocity are symmetric in latitude and the meridional velocity is latitudinally antisymmetric (Matsuno, 1966). Chelton et al. (2003) attributed the observed asymmetry to the mean-shear-induced modifications of first meridional mode Rossby waves. The present paper examines nonlinear rectification of cross-equatorial wave structures in the presence of different zonal mean currents. Nonlinear traveling Rossby waves embedded in shears are calculated numerically in a 1.5-layer model. Nonlinearity is shown to increase the cross-equatorial asymmetry substantially making the northern extrema even more pronounced. However, nonlinearity only slightly increases the magnitude of the westward phase speed.  相似文献   

1961-2010年环渤海地区寒潮时空分布及变化特征   总被引：1，自引：0，他引：1  

段丽瑶  刘爱霞  于莉莉 《气象与环境学报》2013,29(4):54-58

利用1961-2010年环渤海地区58个站的逐日平均气温、日最低气温资料,按照寒潮国家标准统计寒潮次数和寒潮强度,分析环渤海地区单站寒潮和区域寒潮的气候变化特征。结果表明：环渤海地区单站寒潮出现频次的地域差异很大,大体上呈现自北至南递减态势,年平均次数最多的为张北21次,最少的京津地区不足2次。近50 a来环渤海地区共有233次区域性寒潮,出现在当年9月至次年4月,其中11月最多。区域寒潮呈显著减少趋势。20世纪60-70年代区域性寒潮事件频发,80年代开始明显减少并在1983年出现了突变。区域特强寒潮不多,20世纪60年代出现了2次,自70年开始特强寒潮平均每个年代出现1次。在气候变暖背景下,环渤海地区区域寒潮次数明显减少,但特强寒潮亦极端寒潮事件并未减少。  相似文献   

The effect of current and wave on whitecap coverage via relative speed： the Atlantic Ocean case     

于婷  邓增安  管长龙 《中国海洋湖沼学报》2009,27(4):924-930

Whitecapping plays an important role in many air-sea exchange and upper ocean processes. Traditionally, whitecap coverage is parameterized as a function of wind speed only. At present, the relative speed of ocean current to wind is considered to be important in the air-sea exchange parameterization which is the function of wind speed only. In this paper, the effects of ocean surface velocity (current velocity and wave induced velocity) and the wave parameters on whitecap coverage through relative speeds are investigated, by applying a 2-parameter whitecap coverage model to the Atlantic Ocean. It is found that the impacts of both current and wave on whitecap coverage are considerable in the most part of the Atlantic Ocean. It is interesting that the effect of wave is more significant than that of current.  相似文献   

Modification on Lynett and Liu＇s model for internal solitary wave propagation over variable bathymetry     

白晔斐  宋金宝 《中国海洋湖沼学报》2006,24(4):338-344

A two-dimensional, depth-integrated model proposed by Lynett and Liu （2002） was checked carefully, and several misprints in the model were corrected after detailed examination on both the theory and the numerical program. Several comparisons were made on wave profile, system energy and maximum wave amplitude. It is noted that the modified model can simulate the propagation of the internal solitary waves over variable bathymetry more reasonably to a certain degree, and the wave profiles obtained based on the modified model can better fit the experiment data reported by Helfrich （1992） than those from original model.  相似文献   

Recovery of the elastic parameters of a layered half-space     

Paul Sacks  Wolliam Symes 《Geophysical Journal International》1987,88(3):593-620

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Propagation of electromagnetic waves in one-dimensional quasiperiodic media     

V. D. Badalyan 《Astrophysics》2006,49(4):538-542

The angular dependence of the reflection coefficient is studied for electromagnetic waves passing through a one-dimensional quasiperiodic dielectric layer. It is found that for certain types of quasiperiodic systems, omnidirectional reflection of electromagnetic waves can occur. __________ Translated from Astrofizika, Vol. 49, No. 4, pp. 631–636 (November 2006).  相似文献   

Evaluation of Inference Adequacy in Cumulative Logistic Regression Models: An Empirical Validation of ISWRidge Relationships     

Cheng-Wu CHEN  Hsien-Chueh Peter YANG  Chen-Yuan CHEN  Alex Kung-Hsiung CHANG  Tsung-Hao CHEN   《中国海洋工程》2008,22(1):43-56

Internal solitary wave propagation over a submarine ridge results in energy dissipation, in which the hydrodynamic interaction between a wave and ridge affects marine environment. This study analyzes the effects of ridge height and potential energy during wave-ridge interaction with a binary and cumulative logistic regression model. In testing the Global Null Hypothesis, all values are p 〈0.001, with three statistical methods, such as Likelihood Ratio, Score, and Wald. While comparing with two kinds of models, tests values obtained by cumulative logistic regression models are better than those by binary logistic regression models. Although this study employed cumulative logistic regression model, three probability functions p^1, p^2 and p^3, are utilized for investigating the weighted influence of factors on wave reflection. Deviance and Pearson tests are applied to cheek the goodness-of-fit of the proposed model. The analytical results demonstrated that both ridge height （X1 ） and potential energy （X2 ） significantly impact （p 〈 0. 0001 ） the amplitude-based refleeted rate; the P-values for the deviance and Pearson are all 〉 0.05 （0.2839, 0.3438, respectively）. That is, the goodness-of-fit between ridge height （ X1 ） and potential energy （X2） can further predict parameters under the scenario of the best parsimonious model. Investigation of 6 predictive powers （ R2, Max-rescaled R^2, Sorners＇ D, Gamma, Tau-a, and c, respectively） indicate that these predictive estimates of the proposed model have better predictive ability than ridge height alone, and are very similar to the interaction of ridge height and potential energy. It can be concluded that the goodness-of-fit and prediction ability of the cumulative logistic regression model are better than that of the binary logistic regression model.  相似文献   

Variations mechanism in entropy of wave height field and its relation with thermodynamic entropy     

郭佩芳侯一筠  钱成春周良民 《中国海洋湖沼学报》2006,24(1):65-68

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大地构造和海陆起源的内波假说（Ⅰ）──关于板块学说的若干问题及其思考     

池顺良  锤荣融  杨洪之  骆鸣津 《大地测量与地球动力学》1996,(1)

随着资料的积累，不断发现与板块假说相矛盾的事实：地震层析没有发现地幔对流的证据，却发现大陆克拉通具有４００ｋｍ深的“壳根”；海洋地质调查发现了一系列否定板块假说的重要证据，尤其是大西洋中多处发现古岩石，使海底扩张模型受到严重挑战；跨越扩张脊的一系列测量结果实际上否定了扩张假说。此外，作为学说重要支柱的地磁资料的可靠性受到怀疑，板块消减过程中洋底沉积层堆积被否定，大陆碰撞模式与陆上地质资料的不符，动力机制不明，板块模式不适于解释复杂的大陆地质而难以登陆等事实，已令板块构造理论陷入了深刻的危机之中。根据煤和蒸发岩的地史分布等资料，说明一个海陆相对固定的大地构造模型更符合实际。通过对大地构造假说发展史的分析和研究，并借鉴天文学中太阳系的发现史，认为新假说的建立必须从确凿的地质现象，而非多解性的资料和推断出发。由此提出大地构造和海陆起源的内波假说。  相似文献