青藏高原地区云对地面有效辐射的影响：Ⅱ.强迫作用   总被引：2，自引：0，他引：2  

王可丽  钟强 《高原气象》1994,13(2):128-134

本文利用１９８２年８月－１９８３年７月青藏高原地面热源观测试验资料，讨论了与云对地面有效辐射强迫作用有关的参数的计算问题，并对这些参数的计算结果进行了分析。结果表明：晴空、全云条件下的地面有效辐射和云对地面有效辐射强迫作用的年平均日变化振幅有明显的地域差异；云对地面有效辐射的强迫作用春夏大，秋冬小，甘孜、拉萨、那曲和改则４站平均的年平均值为－２７．２Ｗ／ｍ＾２。?  相似文献   

台风移动规律的研究 Ⅱ.小地形与边界层的动力作用   总被引：1，自引：1，他引：1  

贺海晏  杨平章 《热带气象学报》1995,11(2):97-105

从支配台风中心移动的基本方程出发，着重分析了小地形（地形高度与台风系统的的垂直厚度相双为小量）的抬升作用和边界层的摩擦作用对台风移动影响的定性特征。结果表明，较高地势对台风有“吸收”作用；边界层摩擦辐合引起的艾克曼抽吸有利于台风产生沿局地流场引导速度方向的加速度。  相似文献   

地形对于气流运动影响的数值研究   总被引：7，自引：3，他引：7  

肖庆农  伍荣生 《气象学报》1995,53(1):38-49

建立了二维、非静力平衡的数值模式，研究地形对上游气流的阻挡以及大振幅背风波谷与下坡风的形成。结果表明：地形的阻挡效应受地形高度、大气层结及地形非对称性等因子的影响。数值试验与理论分析都证明地形越高、层结越稳定时阻挡作用越强；同样条件下，迎风坡坡度大的地形容易对气流形成阻挡。此外，分析了地形高度、大气层结、地形非对称性以及基本入流大小对背风波谷及下坡风强度影响的规律，并通过一次实际观测对数值模拟结果进行了检验。  相似文献   

台风移动规律的研究　Ⅱ．小地形与边界层的动力作用     

贺海晏  杨平章 《热带气象学报》1995,(2)

从支配台风中心移动的基本方程出发，着重分析了小地形（地形高度与台风系统的垂直厚度相比为小量）的抬升作用和边界层的摩擦作用对台风移动影响的定性特征。结果表明，较高地势对台风有“吸引”作用；边界层摩擦辐合引起的艾克曼抽吸有利于台风产生沿局地流场引导速度方向的加速度。  相似文献   

Numerical experiments on the generation of long ocean waves in coastal waters of the Buenos Aires province,Argentina     

Walter C. Dragani 《Continental Shelf Research》2007

A numerical model (two horizontal dimensions, vertically integrated) is used to investigate the generation of long ocean waves, ranging from 20 min to almost 2 h, at Buenos Aires continental shelf. The domain includes the Río de la Plata estuary and the continental shelf together and extends from 33.5° to 40.5°S latitude, and from 51° to 63°W longitude. Sea-level oscillations are modeled by forcing with passage of atmospheric cold fronts and atmospheric gravity waves. Both forcing mechanisms, which have been present during high activity lapses of long ocean waves, are mathematically implemented. After several numerical simulations, it is concluded that the pressure and wind fields associated to cold fronts do not generate long ocean waves in the area, though they do produce disturbances with periods longer than the tidal ones. On the other hand, it is so concluded that atmospheric gravity waves are an effective mechanism to force long ocean waves. Results obtained show that generation of long ocean waves is highly sensitive depending on the propagation direction and the phase speed of the atmospheric gravity waves. The long ocean wave event detected during the large-amplitude gravity-wave event of 13 October 1985 is successfully simulated. Finally, all our results suggest that atmospheric gravity waves are a highly effective mechanism forcing for the generation of long ocean waves in Buenos Aires coastal waters.  相似文献   

Two different methods of geoidal height determinations using a spherical harmonic representation of the geopotential, topographic corrections and the height anomaly–geoidal height difference     

H. Nahavandchi 《Journal of Geodesy》2002,76(6-7):345-352

 It is suggested that a spherical harmonic representation of the geoidal heights using global Earth gravity models (EGM) might be accurate enough for many applications, although we know that some short-wavelength signals are missing in a potential coefficient model. A `direct' method of geoidal height determination from a global Earth gravity model coefficient alone and an `indirect' approach of geoidal height determination through height anomaly computed from a global gravity model are investigated. In both methods, suitable correction terms are applied. The results of computations in two test areas show that the direct and indirect approaches of geoid height determination yield good agreement with the classical gravimetric geoidal heights which are determined from Stokes' formula. Surprisingly, the results of the indirect method of geoidal height determination yield better agreement with the global positioning system (GPS)-levelling derived geoid heights, which are used to demonstrate such improvements, than the results of gravimetric geoid heights at to the same GPS stations. It has been demonstrated that the application of correction terms in both methods improves the agreement of geoidal heights at GPS-levelling stations. It is also found that the correction terms in the direct method of geoidal height determination are mostly similar to the correction terms used for the indirect determination of geoidal heights from height anomalies. Received: 26 July 2001 / Accepted: 21 February 2002  相似文献   

风应力对热带斜压海洋的强迫   总被引：2，自引：2，他引：2       下载免费PDF全文

巢纪平  陈鲜艳  何金海 《大气科学》2002,26(5):577-594

利用一个线性的具有不同密度、温度的热带海洋两层模式,分析了热带西太平洋对纬圈风应力的响应.解析地求得热带西太平洋温跃层厚度、洋流及海温分布.结果表明次表层温度变化明显要比表层海温变化大,同时在大洋西部次表层发展起来的扰动向东传播能引起海温分布形态的异常.理论结果支持观测己表明的热带西太平洋物理量的变异在ElNino/La Nina事件中起着重要作用的事实.  相似文献   

Topographic and atmospheric corrections of gravimetric geoid determination with special emphasis on the effects of harmonics of degrees zero and one     

L. E. Sjöberg 《Journal of Geodesy》2001,75(5-6):283-290

 The topographic and atmospheric effects of gravimetric geoid determination by the modified Stokes formula, which combines terrestrial gravity and a global geopotential model, are presented. Special emphasis is given to the zero- and first-degree effects. The normal potential is defined in the traditional way, such that the disturbing potential in the exterior of the masses contains no zero- and first-degree harmonics. In contrast, it is shown that, as a result of the topographic masses, the gravimetric geoid includes such harmonics of the order of several centimetres. In addition, the atmosphere contributes with a zero-degree harmonic of magnitude within 1 cm. Received: 5 November 1999 / Accepted: 22 January 2001  相似文献   

平流层温度调整后的辐射强迫的简化计算   总被引：5，自引：0，他引：5  

于秀兰  石广玉 《高原气象》2001,20(3):271-274

采用石广玉[1] 一维辐射对流模式对温室气体浓度变化引起的平流层温度调整后的辐射强迫(ARF)进行了计算。参考文献 [1]的瞬时辐射强迫 (IRF)计算的简化公式的形式 ,将ARF的计算结果表示成简单的经验公式。与使用一维辐射对流模式计算得出的ARF结果的比较表明 ,简化计算公式可以达到很高的精度。  相似文献   

Long internal waves in shear flows: topographic resonance and wave-induced global instability     

Bang-ji Wang  Larry G. Redekopp   《Dynamics of Atmospheres and Oceans》2001,33(4)

Issues pertaining to a mechanism whereby long internal waves in shallow seas may give rise to enhanced rates of resuspension of sedimentary material are addressed. The proposed mechanism is intimately related to the creation of conditions in the bottom boundary layer which are favorable for flow separation and spontaneous onset of global instability. It is shown that long waves generated by topographic resonance and propagating upstream against the oncoming current, especially a sheared current, have a strong tendency to release a coherent, pulsating dynamics in their footprint. The passage-through-resonance problem for a sheared, stratified flow is considered, conditions for topographic resonance in the flow model are defined, and preliminary results for the unsteady dynamics in the boundary layer under the footprint of a long wave packet are presented.  相似文献