大气涛动

<正>大气涛动的研究至今已有百年以上的历史。19世纪末,当人们开始绘制月平均海平面气压图时,就发现了"大气活动中心",即相对稳定的高压区或低压区。有些低压及高压终年存在,被称为永久性活动中心,如北大西洋上的冰岛低压和亚述尔高压、北太平洋上的阿留申     

Global diagnostic energetics of five state-of-the-art climate models

In this study, the global energy cycle of five state-of-the-art climate models is evaluated in the wave number domain for all seasons. The energy cycle estimates are based on 30?years of 6-hourly data obtained at pressure levels of all models. The models energetics are compared to those obtained from three reanalysis datasets (ERA-40, JRA-25 and NCEP-R2). The results show that the distributions of the energetics integrands and the shape of the various wave number spectra are reasonably well simulated. Many important features can be found in most models, namely both the upscale and downscale energy cascade for the wave?Cwave interactions of kinetic energy, the downscale energy cascade for the wave?Cwave interactions of available potential energy and the downscale energy transfer for the zonal?Cwave interactions of kinetic energy. However, the magnitude in the integrands distributions is generally excessive, yielding too much energy and an overactive energy cycle in the models. Accordingly, this energy excess is also reflected in the various spectra, specially but not exclusively, at the synoptic scale wave numbers for the energy conversion/transfer rates. The well known cold pole bias and the too strong tropospheric jets, along with their dislocation in some cases, still persist in the climate models. These are some of the deficiencies in the models directly implicated in the energy cycle. Apparently, simply increasing the horizontal and vertical resolutions is not enough to eliminate these deficiencies due to somewhat opposite effects achieved by refining both spatial resolutions. Therefore, more accurate physics parameterisations as well as improved numerical schemes and resolution dependence of parameterisations seem to be essential for a significant improvement in the models energetics. Moreover, efforts should be made to improve the physical processes controlling the generation of zonal available potential energy and dissipation of eddy kinetic energy, in which the synoptic scale should be fundamental, as inferred from the excessive energy conversion/transfer rates in the models spectra.     

Global Atmospheric Watch

CAMSisresponsibleforthescientific/technicalsupporttotheGAW(GlobalAtmosphereWatch).monitoringprogramincludingoneGAWbaselinestation(ChinaGlobalAtmosphereWatchBaselinelObservatory-CGAWBO),threeGAWregionalstationsandanational-wideacidrainmonitoringnetworkofI86sites.Inthesestations,thelong-termcomprehensiveatmosphericmonitoringofCO=,CO,CH',Ozone.(totalandsurface),SO=,precipitation(acidrain)chemistry,aerosolchemistry,solarradiation,meteorologicallelements,etc.isconducted.Themajorprogre…     

Stratified Atmospheric Boundary Layers

Various features of different stability regimes of the stable boundary layer are discussed. Traditional layering is examined in terms of the roughness sublayer, surface layer, local similarity, z-less stratification and the region near the boundary-layer top. In the very stable case, the strongest turbulence may be detached from the surface and generated by shear associated with a low level jet, gravity waves or meandering motions. In this case, similarity theory and the traditional concept of a boundary-layer break down. The elevated turbulence may intermittently recouple to the surface. Inability to adequately measure turbulent fluxes in very stable conditions limits our knowledge of this regime.     

Advances in Atmospheric Sciences

PAPER TITLE: AUTHOR(S): The author warrants that his/her contribution is original,has not been published previously,and is not under consideration for publication in any other refereed journals.And he/she has full power to make this grant.All authors sign for and accept responsibility for releasing this material. If the author needs to submit the paper elsewhere during the review process,he/she must declare its withdrawal to the editor prior to such submission.     

Atmospheric chemistry of alkanes

The reactions of the alkanes under atmospheric conditions and in the presence of oxides of nitrogen are reviewed and evaluated. Particular emphasis is placed upon their subsequent reactions after the initial OH radical reaction under conditions where the alkyl peroxy radicals produced react predominantly with NO, rather than with HO₂ and/or RO₂ radicals. Methods are discussed for estimating the overall OH radical rate constants, the number of molecules of NO consumed per alkane molecule reacted, and the products formed and their yields.     

Atmospheric circulation climate changes

The role of the atmospheric circulation in climate change is examined. A review is given of the information available in the past record on the atmosheric circulation and its role in climate change, firstly at the surface via sea level pressure in both the northern and southern hemispheres and secondly for the free atmosphere. As with most climate information, the climate record is compromised by non-physical inhomogeneities arising from changes in observing and analyzing techniques and changes in data coverage. Problems with and threats to the rawinsonde network are discussed. Global analyses produced by the operational centers, U.S. National Meteorological Center (NMC) and the European Centre for Medium Range Weather Forecasts (ECMWF), for weather forecasting purposes contain many discontinuous changes in the analyses arising from improvements in the system used to produce them. A discussion is given of the prospects for and motivation behind an activity known as reanalysis in which the historical data are reanalyzed using a state-of-the-art system that is held constant for the entire record. The only sources of spurious change then are the changes in the observing system, such as the introduction of space-based observations. Recommendations are made on needed actions for better understanding and monitoring climate change.The role of the atmospheric circulation and the strong links to other variables such as temperature, precipitation and wind are established and illustrated with a survey of decadal variability, the evidence for it, and the way in which the observed atmospheric circulation is involved in the Pacific and Atlantic sectors. The importance of teleconnections is stressed, especially in the winter half year, for understanding local climate change. The likelihood that changes will be manifested in the frequency and intensity of preferred modes of behavior in the atmosphere, such as the El Niño-Southern Oscillation and Pacific-North American teleconnection patterns, rather than in changes in the modes is also emphasized. The recently observed climate changes and the tendency for an unprecedented prolonged El Niño are interpreted in this framework. The key coupled atmosphere-ocean character of decadal variability is noted with the atmosphere providing the spatial scales, the ocean the memory, but also with the need for collaborative, as opposed to destructive, interactions through the atmospheric circulation.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

广义大气密度函数

把大气密度函数的定义从几何空间扩大到相空间(如压力温度等),引入了广义大气密度函数概念,讨论了这个函数的计算方法和积分特点,给出了两个简单的广义大气密度函数实例,还讨论了相空间中的大气方程组问题。     

大气水分循环方程

任何地点的降水量可能来自地球的任何地点的水分蒸发。为了定量描述大气中的这种水分循环的复杂过程,我们引入了两个概念性的工具:大气水分辐合函数和大气水分辐散函数,并且建立了用它们描述大气水分循环的方程组。     

Stratospheric final warmings in the Southern Hemisphere and their energetics

Summary.  Using 9 years (1985–1993) data, final stratospheric warmings in the Southern Hemisphere are studied. Interannual variations in the onset date and the temperatures are noted. In 1985 the stratosphere was colder by about 5 K and the wave activity was less. This year the final warming got delayed. In contrast in 1988 the final warming occurred earlier when compared with the mean picture and the wave activity was more. An examination of Eliassen-Palm fluxes showed the important role of planetary waves in the wave-mean flow interaction. In the energetics the most spectacular change is the reduction of zonal kinetic energy. Before the warming the energy exchanges were P_z → P_e → K_e → K_z ← P_z and after the warming they were P_z ← P_e ← K_e → K_z ← P_z. The dramatic reduction of zonal kinetic energy seems to be due to two effects: the reduction in K_e → K_z conversion and the weakening of direct meridional circulation. Received October 3, 2001; revised June 5, 2002     

Comparative energetics analysis of CCM2 with different horizontal resolutions

 Comprehensive global energetics analysis is carried out for the NCAR CCM2 with different horizontal resolutions of R15, T42, T63, and T106 to assess the effect of various model truncations on the global energetics characteristics in climate models. Both the energy levels and energy transformations are examined over the zonal wave number domain during a northern winter and summer. In addition to the simulated atmosphere, the ECMWF global analysis during 1986 to 1990 is analyzed for comparison using the same diagnostic scheme. Previous studies have revealed that zonal kinetic energy is supplied by synoptic disturbances in terms of the zonal-wave interactions of kinetic energy. According to our result, however, such an energy flow from eddies to zonal motions is valid only for zonal wave numbers up to about 30. We find that the zonal-wave interactions of kinetic energy change sign beyond wave number 30 where the energy is transformed from zonal to eddies for both the ECMWF and CCM2-T106. The large-scale zonal motions are diffusive against the short waves beyond wave number 30, which may well be parameterized by various forms of the diffusion schemes. We suggest from this result that the atmospheric disturbances with wave numbers lower than 30 are necessary to represent accurately the two-way interactions between zonal and eddy motions, because these waves can actively influence the behavior of the zonal motions. Based on this finding, we suggest that the model resolution of R15 is inadequate for climate studies from the energetics point of view, and that resolution of T42 is the minimum requirement to represent the general circulation adequately. Some other discrepancies are discussed in detail for the coarse resolution climate models. Received: 15 July 1996/Accepted: 3 January 1997     

大气边界层和大气环境研究进展

大气边界层物理和大气环境是大气科学的重要领域,中国科学院大气物理研究所自成立以来在这一研究领域取导了丰硕的成果.作者重点介绍最近十多年来在大气边界层探测、大气边界层结构特征、大气湍流理论、城市和区域大气污染预测预报模式研究等方面取得的重要进展,并对大气边界层和大气环境研究的未来发展作了展望.