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七月大气环流对南极海冰异常的响应 总被引：2，自引：0，他引：2
本文用一个全球大气九层谱模式，模拟了七月份南极两个不同海区海冰区异常对大气环流的影响。主要讨论了大气环流对南极海冰异常存在的局地性的及全球性的响应。细致分析了二个区域极冰异常导致的南北半球低频波列分布的差异，以及它们对热带区域及亚洲季风区降水、越赤道气流的不同影响。最后则依据我们的模拟结果，讨论了南极海冰异常影响全球大气环流的动力学机制。 相似文献
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该文分析了1991年7月中国江淮暴雨洪水期间赤道太平洋沃克环流及沿115°E哈得莱环流的逐日演变特征。结果发现在暴雨时期赤道东风减弱，西风加强，反哈得莱环流（即季风环流）在中国东部上空加强。在暴雨期间，高低空散度风场的分析指出，在低空出现明显的散度风越赤道气流，而在对流层上部出现散度风的流出。 相似文献
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Jin-Song von Storch 《Ocean Dynamics》2003,53(1):11-20
The three-dimensional time-mean density distribution in the ocean is determined not only by the time-mean fluxes of heat
and freshwater at the sea surface, but also by time-mean vertical currents and time-mean density fluxes due to oceanic transients
excited by fluctuating fluxes at the sea surface. The effects of these various processes on the global density fields are
assessed using a balance equation of the variance of spatial density anomalies and a millennium integration with an atmosphere–ocean
general circulation model. It is found that spatial density anomalies are generated by the time-mean heat fluxes at the sea
surface and destroyed by the time-mean surface freshwater flux, by sinking of dense water and rising of less dense water,
and finally by density fluxes associated with transients. The last two processes take place essentially in the oceanic interior.
Since density fluxes of transient eddies act to reduce the existing density differences between the Atlantic/Southern Oceans
and the other oceans, their presence could affect the global density balance, and from that the thermohaline circulation and
the stability of this circulation.
Received: 4 October 2001 / Accepted: 10 October 2002
Responsible Editor: Richard J. Greatbatch
Acknowledgements I thank Ulrich Cubasch and his colleagues for providing me with the ECHAM3/LSG integration, Peter Müller and Richard Greatbatch
for valuable suggestions. 相似文献
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The Lagrangian surface drift current induced by surface gravity waves in a wave flume has been investigated experimentally by the particle tracking method. It was observed that in most regions of the flume, the time-mean surface drift current was in the opposite direction to that of the wave propagation. The secondary current in the form of a pair of longitudinal vortices caused by the lateral boundaries was analyzed. It is suggested that the convection of the vorticity generated by the wave-absorber and the lateral boundaries is an important factor in the determination of the time-mean drift in a wave flume. 相似文献
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The motions and time-mean horizontal drift forces of floating backward-bent duct buoy wave energy absorbers in regular waves are calculated taking account of the oscillating surface-pressure due to the pressure drop in the air chamber above the oscillating water column within the scope of the linear wave theory. The present numerical results show that the time-mean drift forces of backward-bent duct buoys are in the reverse direction of propagation of the incident waves over specific frequency ranges as found by McCormick through his experimental work. The drift force has been calculated by the near-field method. A brief discussion on Maruo’s formula which shows that the time-mean drift force must be in the direction of propagation of the incident waves, has also been presented. 相似文献
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Utilizing Eliassen’s concepts, the forcing of the isentropic azimuthally-averaged mass-weighted radial-vertical circulation by diabatic heating and torques within an extratropical cyclone and a typhoon was studied through nu-merical simulations based on the linear diagnostic equation derived previously. The structure of the forcing associated with diabatic heating and torques was determined from quasi-Lagrangian diagnostic analyses of actual case studies. The two cyclones studied were the Ohio extratropical cyclone of 25-27 January 1978 and typhoon Nancy of 18-23 September 1979. The Ohio cyclone, which formed over the Gulf Coast and moved through Ohio and eastern Michigan, was one of the most intense storms with blizzard conditions to ever occur in this region. Typhoon Nancy which occurred over the South China Sea during the FGGE year was selected since relatively high quality assimilated data were available. Within the Ohio cyclone, the dominant internal processes forcing the mean circulation with em-bedded relatively strong hydrodynamic stability were the pressure torque associated with baroclinic (asymmetric) structure and the horizontal eddy angular momentum transport associated with the typical S-shaped thermal and wind structures of self-development. Within typhoon Nancy, the dominant internal process forcing the mean circula-tion with embedded weak hydrodynamic stability was the latent heat release. This analysis shows that the simulated azimuthally-averaged mass-weighted radial motions within these two cy?clones agree quite well with the “observed” azimuthally-averaged mass-weighted radial motions. This isentropic nu?merical study also provides insight into the relatively important internal forcing processes and the trade off between forcing and stability within both extratropical and tropical cyclones. 相似文献
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本文提出一个对包括下垫面温度在内的未知总强迫项进行参数化作平均环流的预报方法.该参数化方案是假设未知作用力距平与流函数距平成正比,其比例系数是空间位置的函数,得到一个平均环流距平的预报方程.该方程表明,预报结果的好坏不仅取决于初始状态和动力学的考虑,还取决于环流的历史演变情况. 根据历史资料反求其比例系数,所作的平均环流距平的历史拟合结果令人满意.独立样本的预报结果比不上历史拟合的结果.试验结果还表明,如果加长历史资料的时间序列,把310天的历史资料增加到620天,则独立样本的预报结果有较大的改善,不仅有很多旬平均和月平均的个例非常成功,而且预报的半均准确率已超过一般惯性预报的水平. 相似文献
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海陆分布和地形对大气垂直环流影响的诊断研究 总被引：1，自引：1，他引：0
本文利用GFDL10年平均的气候资料,分析了海陆分布和地形对大气中经圈和纬圈垂直环流的影响。文中提出了用运动学方法分别在P和σ坐标系中计算大气垂直运动ω或W的新方法。讨论了欧亚非洲季风的垂直环流特征,并与非季风区相应垂直环流围进行了比较。结果表明,在具有明显南北向海陆差异的经度上（如欧亚大陆所在处）,垂直的季风经圈环流具有较大的强度,且有明显的季节变化。而在只有海洋的经度上,垂直经圈环流较弱,季节变化不明显。在纬圈方向,垂直环流圈在海陆差异较大的北半球中高纬度带也比海陆差异较小的低纬和赤道地区复杂得多。地形的作用迭加于海陆热力差异的作用之上,加强了地形区和自由大气间的热力差异,使青藏高原和落基山脉所在的经度带内的垂直环流圈变得更加复杂,季节变化更明显。 相似文献
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