Characteristics and evolution of a coastal mesoscale eddy in the Western Bay of Bengal monitored by high-frequency radars     

《Dynamics of Atmospheres and Oceans》2019

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Falling sphere observations of anisotropic gravity wave motions in the upper stratosphere over Australia   总被引：1，自引：0，他引：1  

Stephen D. Eckermann  Robert A. Vincent 《Pure and Applied Geophysics》1989,130(2-3):509-532

A study of inertial scale gravity wave motions in the region of the atmosphere between 30 and 60 km has been undertaken, using wind and temperature data derived from rocket-borne falling sphere density experiments performed over Woomera, Australia between 1962 nad 1976. The gross features of the wave field compare favorably with those found in similar northern hemispheric studies. Wave propagation is found to be both vertically and horizontally anisotropic. A rotary spectral analysis indicates predominately upgoing wave energy, suggesting that the majority of sources of these waves lie below 30 km. A detailed statistical investigation of the waves, made using the Stokes parameters technique, reveals that phase progression is also highly directional in the horizontal, with a significant zonal component in summer, but with a strong meridional component in winter. Propagation towards the southeast is inferred in summer, with the waves possibly emanating from tropospheric sources in equatorial regions to the north of Australia. The technique also shows that, on average, the waves appear to have mean ellipse eccentricities (=f/) around 0.4–0.45. Indirect estimates of a number of important wave parameters are made. In particular,v andw flux estimates are made over several height intervals. The vertical gradient of density weighted flux implies wave-induced mean flow accelerations of the order 0.1–1 ms^–1day^–1. This suggests that dissipating gravity waves are a significant source of the momentum residuals that are encountered in studies of satellite data from this region.  相似文献   

Temperature and heat flux spectra in the turbulent buoyancy subrange     

C. Sidi  F. Dalaudier 《Pure and Applied Geophysics》1989,130(2-3):547-569

The physical nature of motions with scales intermediate between approximately isotropic turbulence and quasi-linear internal gravity waves is not understood at the present time. Such motions play an important role in the energetics of small scales processes, both in the ocean and in the atmosphere, and in vertical transport of heat and constituents. This scale range is currently interpreted either as a saturated gravity waves field or as a buoyancy range of turbulence.We first discuss some distinctive predictions of the classical (Lumley, Phillips) buoyancy range theory, recently improved (Weinstock, Dalaudier and Sidi) to describe potential energy associated with temperature fluctuations. This theory predicts the existence of a spectral gap in the temperature spectra and of an upward mass flux (downward buoyancy and heat fluxes), strongly increasing towards large scales. These predictions are contrasted with an alternate theory, assuming energetically insignificant buoyancy flux, proposed by Holloway.Then we present experimental evidences of such characteristic features obtained in the lower stratosphere with an instrumented balloon. Spectra of temperature, vertical velocity, and cospectra of both, obtained in homogeneous, weakly turbulent regions, are compared with theoretical predictions. These results are strongly consistent with the improved classical buoyancy range theory and support the existence of a significant downward heat flux in the buoyancy range.The theoretical implications of the understanding of this scale range are discussed. Many experimental evidences consistently show the need for an anisotropic theory of the buoyancy range of turbulence.  相似文献   

大气红外窗区(10.5-11.5μm和11.5-12.5μm)辐射传输的敏感性试验   总被引：1，自引：0，他引：1  

魏丽  钟强 《高原气象》1988,(3)

大气窗区卫星红外遥感的辐射资料可应用于地表温度的确定,但必须考虑大气影响。为此,本文利用辐射传输模式和中纬度及青藏高原模式大气,用数值模拟的方法研究了大气和地表状态(大气温、湿廓线、地表温度与高度)的改变对大气顶红外窗区射出辐射的影响以及射出辐射对发射方向(天顶角)依赖关系。主要结论见正文小结。  相似文献   

1991年江淮梅雨暴雨与亚洲季风的关系     

乔全明  罗坚  杨信杰  费建芳  陈凤贵 《热带气象学报》1994,10(1):64-68

利用实际大气参数取值进行尺度分析，求得斜压半地转模式中非线性斜压Ｒｏｓｓｂｙ波的非频散周期解的存在条件与解。给出了能够描述非线性特性波动的无量纲拟能效ε，由此推导了非线性特征波动的波速公式及波参数间的一些诊断关系。  相似文献   

Numerical study of the oxidation process of dimethylsulfide in the marine atmosphere   总被引：1，自引：0，他引：1  

Seizi Koga  Hiroshi Tanaka 《Journal of Atmospheric Chemistry》1993,17(3):201-228

A box model, involving simple heterogeneous reaction processes associated with the production of non-sea-salt sulfate (nss-SO ₄ ^2– ) particles, is used to investigate the oxidation processes of dimethylsulfide (DMS or CH₃SCH₃) in the marine atmosphere. The model is applied to chemical reactions in the atmospheric surface mixing layer, at intervals of 15 degrees latitude between 60° N and 60° S. Given that the addition reaction of the hydroxyl radical (OH) to the sulfur atom in the DMS molecule is faster at lower temperature than at higher temperature and that it is the predominant pathway for the production of methanesulfonic acid (MSA or CH₃SO₃H), the results can well explain both the increasing tendency of the molar ratio of MSA to nss-SO ₄ ^2– toward higher latitudes and the uniform distribution with latitude of sulfur dioxide (SO₂). The predicted production rate of MSA increases with increasing latitude due to the elevated rate constant of the addition reaction at lower temperature. Since latitudinal distributions of OH concentration and DMS reaction rate with OH are opposite, a uniform production rate of SO₂ is realized over the globe. The primary sink of DMS in unpolluted air is caused by the reaction with OH. Reaction of DMS with the nitrate radical (NO₃) also reduces DMS concentration but it is less important compared with that of OH. Concentrations of SO₂, MSA, and nss-SO ₄ ^2– are almost independent of NO _x concentration and radiation field. If dimethylsulfoxide (DMSO or CH₃S(O)CH₃) is produced by the addition reaction and further converted to sulfuric acid (H₂SO₄) in an aqueous solution of cloud droplets, the oxidation process of DMSO might be important for the production of aerosol particles containing nss-SO ₄ ^2– at high latitudes.  相似文献   

1989年中日青藏高原冰川联合考察研究   总被引：3，自引：1，他引：3  

姚檀栋  上田丰 《冰川冻土》1991,13(1):1-8

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参考大气在中期天气预报和气候模拟中的应用     

陈嘉滨  舒静君 《大气科学》1994,18(6):660-673

本文概述了根据应用参考大气概念提出的参考大气谱模式计算格式（或称静力扣除法）在国内外一些气象机构的中期天气预报、后处理和四维同化、以及气候模拟中的应用。计算表明，这种参考大气谱模式计算格式，能有效的减少截谱误差，明显地改进中期天气预报和气候模拟。  相似文献   

沙漠地区春季的大气浑浊度及沙尘大气对地面辐射平衡的影响   总被引：10，自引：8，他引：10  

沈志宝  文军 《高原气象》1994,13(3):330-338

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TROPICAL ATMOSPHERIC NONLINEAR STEADY RESPONSE SOLUTION UNDER EFFECTS OF PAIRED HEAT SOURCES OF CONTRASTING NATURE          下载免费PDF全文

周学龙  孙照渤 《Acta Meteorologica Sinica》1994,(3)

Based on steady semi-geostrophic model equations,analysis is carried out of the linear and nonlinearmodification/response of the tropical atmosphere to the forcing of ideal paired heat sources of contrasting nature.Re-suits show that the linear part is dominant in the steady response but the nonlinear modification is quite noticable in theneighborhood of the heat source and between the paired sources,and the barotropic mode and second baroclinic modeplay a different role in the modification,with the barotropic(second baroclinic)mode modification depending largely onthe Rossby wave self-interaction(the magnitude due to the Kelvin-Rossby wave interaction)between the pairedsources.  相似文献