大气对称运动和反对称运动的物理性质以及它们之间的能量转换

采用p坐标系,利用控制原始方程模式大气中对称运动和反对称运动的方程组,对其物理性质,如对称的和反对称的能量、角动量等的守恒性和它们之间的相互转换,纬圈平均的和扰动的对称和反对称运动之间的能量的相互转换进行了讨论。结果指出:(1)对全球总的绝对角动量的变化有贡献的,只能是因地形而引起的位势高度的对称部分在纬圈方向的差值和耗失力的纬向分量;(2)不同形式能量之间的相互转换除和经典的情况类似外,还有对称能量和反对称能量之间的相互转换,可以制约对称运动和反对称运动的相互影响。     

FEATURES OF ENERGY BUDGET AND CONVERSION OF DEVELOPED AND UNDEVELOPED TROPICAL CYCLONE

With two cases of local tropical disturbances in both developed and undeveloped phases, contributions to the genesis and development by kinetic formation and transfer from divergent and nondivergent winds are studied using energy budget equations. Computations are done of conversion kinetic energy between the two types of winds. The result indicates that the subgrid scale effect is the principal source of kinetic energy for a tropical cyclone to grow into a typhoon; the cumulus convection plays a dominant role, in company of relatively weaker contributions on vdrious phases of the life cycle by convergence of fluxes of divergent and nondivergent winds as well as the formation of kinetic energy by the former wind. It is also suggested that the conversion of kinetic energy between the divergent and nondivergent winds C(K_x, K_ψ)is increasing with the development of disturbance mainly due to the contribution by C₁=f^▽Χ^▽ψ. The disturbance is shown in the distribution of C(K_x, K_ψ) to increase in a favorable anticyclonic outflow corresponding to the upper level where the conversion becomes negative in developing and mature phases while the wind velocity increases with enhanced conversion fr0m K_x to K_ψ the lower level in association with the growth of the disturbance. In addition,geopotential energy P converts to kinetic energy of the divergent wind in every stage from formation to mature of the disturbance by means of C(P, K_x), the maximum appearing on the middle and upper layers of the troposphere.The intensity of C(P, K_x) is consistently in phase with variation of C(K_x, K_ψ).     

ENERGY EQUATION AND SYMMETRIC INSTABILITY CRITERION

In this paper,by using generalized normal mode method the symmetric instability criterion which can be used not only in the constant parameters but also in the variable parameters was derived from the energy equation on the symmetric disturbance.If the thermal wind was in balance or quasi-balance,the criterion was consistent with that obtained by Emanuel with parcel method and Hoskins with normal mode method.It is shown that in the generating stage of disturbance,the symmetrically instable development of disturbance is associated with the energy transformation by which the energy of the basic field is transferred into the energy of the disturbance field.     

北半球风暴轴附近的能量转换

用１９８０￣１９８４年的ＥＣＭＷＦ客观分析资料，对任选一年的任意月份、正常年和尼尔尼诺年的特别月份天气尺度涡动能量及其与时间平均气流之间的能量转换项进行了分析。结果表明：在风暴轴区域，天气尺度涡动动能和天气尺度涡动有效位能最大，天气尺度涡动与时间平均气流之间的能量转换也是最剧烈；在风暴轴的入口区、出口区，天气尺度涡动与时间平均气流之间的能量转换是反向的，从而使风暴轴维持在比较常定的区域。     

NUMERICAL EXPERIMENTS IN SYMMETRIC AND ASYMMETRIC MOTIONS IN THE BAROTROPIC PRIMITIVE EQUATION MODEL ATMOSPHERE

Three numerical experiments have been carried out by using a spectral barotropic primitive equation mo-del.It is found that the results obtained are quite similar to those with the barotropic filtered model.Themain results read as follows:(1)In the case with symmetric orography or without orography,if the motion is symmetric(with re-spect to the equator,the same is true hereafter)at the initial instant,then it would be symmetric afterwards.(2)The antisymmetric orography distribution could cause antisymmetric motion,and the original sym-metric motion might become asymmetric.In order to explain the above results,it has been proved that they are theoretically valid.And it is foundthat if the motion is antisymmetric at the initial instant,then it would become asymmetric.Therefore,nopure antisymmetric motion could be maintained.     

CHARACTERISTICS OF GRAVITY WAVE PROPAGATION AND ENERGY CONVERSION IN A SUDDEN HEAVY RAINFALL EVENT

In this paper, a sudden heavy rainfall event is analyzed, which occurred over the Yellow River midstream during 5–6 August 2014. We used observational, NCEP/NCAR reanalysis, high-resolution satellite, and numerical simulation data. The main results are as follows. Under an unfavorable environmental circulation, inadequate water vapor and unfavorable dynamic conditions but sufficient energy, a local sudden heavy rainfall was caused by the release of strong unstable energy that was triggered by cold air transport into middle and lower layers and the propagation of gravity waves. The distributions of rain area, rain clusters, and 10-minute rainfall showed typical mesoscale and microscale fluctuation characteristics. In the mesoscale rain area or upstream, there was a quasi-stationary wave of mesoscale gravity waves with their propagation downstream. In the course of propagation from southwest to northeast, the wavelength became longer and the amplitude attenuated. In the various phases of gravity wave development, there were evident differences in the direction of the wave front. Wave energy was mainly in the lower layers. Unstable vertical wind shear at heights of 1–6 km provided fluctuation energy for the gravity waves. The mechanisms of heavy rainfall formation were different at Linyou and Hancheng stations. Diabatic heating was the main source of disturbed effective potential energy at Linyou. The explosive short-period strong precipitation was caused by the release of strong effective potential energy triggered by the gravity waves, and its development and propagation after that energy maximized. In contrast, the latent heat release of upstream precipitation was the main source of disturbed effective potential energy at Hancheng. This formed a positive feedback mechanism that produced continuous precipitation. In the studied event, the development of westerly belt systems had disturbed the wind field. The contribution of kinetic energy generated by this disturbance could not be ignored. The Froude number, mountain shape parameter, and ratio between mountain height and temperature inversion layer thickness had various effects of atmosphere and terrain on mesoscale and microscale mountain waves. In upper and lower layers, there were five airflows that were strengthened by the terrain. All these had important influences on local heavy rainfall at Linyou and Hancheng stations.     

云南暴雨涡散场动能转换函数的动态分析

对1996年云南主汛期（6－8月）逐日散度风动能和旋转风动能之间的转换函数C（KD,KR）特征进行深入研究,同时分析了C（KD,KR）各项Af、Az、B、C在动能转换函数中所起的作用。研究结果表明,对流层内C（KD,KR）＞0,同时对流层低层的C（K,KR）＞中高层的C（KD,KR）之和．极易出现暴雨过程;Af项在整个动能转换中起主要作用,71％的Af与C（KD,KR）具有相同的符号,Az项和B项在动能转换中起振荡作用,Az＋B控制着29％的动能转换方向。     

北上台风暴雨过程涡散场的能量收支和转换特征

利用辐散风和旋转风的动能收支方程,对北方一次北上台风倒槽暴雨过程暴雨区内的涡散场能量收支和转换进行了计算.结果表明:暴雨区内动能的增加是暴雨增幅的一个主要原因.暴雨发展时,就旋转风动能(K_R)而言,旋转风动能通量(HFR)辐合是主要能源,而旋转风的动能产生项(GR)是主要能汇;就辐散风动能(K_D)而言,辐散风的动能产生项(GD)是主要能源,辐散风动能通量(HFD)辐散是主要能汇;总动能水平通量(HF)提供的辐合主要表现于对流层中、低层,这就使得低层辐合加强,上升运动加强,有利于暴雨的增幅.在暴雨过程中次网格尺度效应由能源转变为能汇,在暴雨发展之时能汇减小;能量的转换项C(K_D,K_R)总为正值,在转换项中,地转效应项的贡献很大.说明暴雨过程能量均由K_D向K_R转换,也就是说有效位能经K_D向K_R转换,充分说明了在整个暴雨过程中,尽管辐散风动能变化(∂K_D/∂t)很小,但是它在其中充当“桥梁”作用,C(K_D,K_R)在暴雨发展时达到最大,此时能量转换最为旺盛;对流层低层辐散风动能向旋转风动能的转换是暴雨产生和发展的重要条件.此次暴雨过程,在暴雨区内表现为斜压不稳定和正压稳定共存的特征,其发展过程是系统斜压不稳定增长,正压稳定性减弱的过程,暴雨增幅的另一个重要原因就是暴雨区内低层斜压的发展.     

动能的周期变化和动能转换率对动能增衰的作用

利用1976～1977年冬季四个月北半球500mb资料,对北半球平均动能和涡动动能波谱的中期变化、动能转换率对平均动能的增衰和对波动增衰的作用进行了研究,得到一些初步结果。指出:北半球平均动能、涡动动能以及涡动动能和平均动能之间的转换率,有准两周的周期振动。涡动动能先于动能转换率一天达到峰值,而后再过两天平均动能达到峰值。在k=3波时,动能也存在准两周的周期振动,它是对涡动动能总值贡献最大的波动,同涡动动能总值具有同位相的振动。对动能转换率总值贡献最大的还是k=3波,其转换率具有同转换率总值同位相的准两周振动。动能转换率对平均动能整个增长阶段的贡献,大于衰退阶段,在平均动能增长阶段,动能转换率近似于同平均动能变化率平衡。这意味着平均动能的增长,正压过程在起作用。文中还研究了动能转换率对k=1～6波增衰的作用,结果表明:它对波动的增长不起作用,但对波动的衰退起到足够的贡献。最后,对波动的增衰同平均动能和涡动动能的中期变化之间的联系进行了讨论。     

亚洲季风变动与大气正压/斜压运动动能变化的气候特征

使用ＮＣＥＰ／ＮＣＡＲ４０年（１９５８～１９９７年）月平均再分析资料,通过动力学论断研究了大气斜压／正压运动动能的变化及其相互转换,分析了亚洲季风变动与这两种动能变化的联系。指出：季风区大气运动动能的组成和变化具有独特的特征。冬季风时期大气斜压运动动能与正压运动动能具有正相关线性关系,斜压运动能向正压运动动能转换;春、秋季无论是东亚还是印度季风区斜压运动动能与正压运动动能之间转换都处于极小值,只是     

ON THE SYMMETRIC DEVELOPMENT OF MESOSCALE DISTURBANCES

The effects of baroclinic basic flow on a paralleled mesoscale disturbance development are investigated.By using the WKB method,two-dimensional perturbation equations with the anelastic approximation areanalyzed.The result indicates that the symmetric development of a mesoscale disturbance is due to the in-homogeneous thermal wind deviations and unstationality of the basic field.     

暴雨区的能量积聚和释放

从第二类有限区域湿有效能量收支方程出发,计算方程主要几项的数值,分析广东省三次暴雨的能量积聚和释放。结果表明：暴雨区及其临近地区在暴雨过程之前、暴雨中期和暴雨之后,不但各项的数值有很大差异,而且各项所起的作用也明显不同。     

对流层中层动能的全球性季节过渡与季节性急变

本文利用１９８０—１９８８年ＥＣＭＷＦ全球资料，计算了５００ｈＰａ各纬度带上的纬向平均动能（Ｋｚ）、涡动动能（ＫＥ）及波数域动能（Ｋｎ，ｎ＝１，２，３，…，１０）。以此考察了南、北半球动能季节过渡的差异，并用Ｔ检验方法讨论了南、北半球以及全球各动能模态的季节性急变现象。现在工作单位：     

鼎湖山针阔叶混交林生态系统能量平衡分析

能量平衡分析作为评价涡度相关法通量观测数据可靠性方法，备受学界重视。应用OLS（Ordinary least squares）和EBR（Energy Balance Ratio）2种方法，系统分析了广东省鼎湖山针阔叶混交林生态系统能量平衡特点，并分析各种涡度通量修正方法对能量平衡的影响，结果表明鼎湖山通量站平均能力平衡不闭合度为33％-47％，略高于普遍报道的不闭合度范围（10％-30％）。WPL修正、μ＊订正和坐标转换，使得能量平衡闭合度有所提高，但夜间特别是冬季能量平衡较差问题依然没有得到根本解决，表明夜间弱湍流并不是导致夜间能量平衡闭合度差的主要原因。为客观评价本通量站以及ChinaFLUX能量平衡状况和通量数据质量，确定涡度相关法CO2通量数据分析方法和改进策略提供依据。     

EFFECT OF ENERGY DISPERSION ON THE STRUCTURE AND MOTION OF TROPICAL CYCLONE

The energy dispersion of a typhoon vortex and its effect on the typhoon motion are studied using an analyticalmethod of double-Fourier expansion as well as a numerical model in a β-plane nondivergent barotropic framework.The analytic model and the linear version of the numerical model give essentially the same result:the energy dispersionfrom a tropical cyclone can creat an L-H-L wave train to the east of the tropical cyclone.Three numerical experiments,integrated for 7 model days by the nonlinear model,indicate that the closed high in the wave train produces obvious in-fluence on the structure and movement of the tropical cyclone.     

小张庄近地面大气环境特性变化观测分析

根据１９９３年１０月,１９９５年５月和１９９７年４月在农业生态环境“全球５００佳”－安徽省颖上县小张庄（３４°４７′Ｎ,１１６°２３′Ｅ）所进行的近地面污染气体（ＳＯ２,Ｏ３,ＮＯｘ）和气溶胶的观测结果,给出了这些微量气体的浓度平均概况及随时间和季节变化的一些特征,这三次观测表明,小张庄大气环境质量是持续好的,地面Ｏ３浓度主要取决于地面总辐射强度控制下的光化学反应过程;小张庄大气气溶胶粒子９９％是     

ANALYSIS ON THE SOURCE AND SINK OF KINETIC ENERGY OF ATMOSPHERIC 30-60 DAY PERIOD OSCILLATION AND THE PROBABLE CAUSES*

Based on ECMWF daily grid point data in summer(May-August),1981,the distribution features of the source and sink of kinetic energy of atmosphere 30-60 day oscillation,including its horizontal distribution characteristics and its vertical structure characteristics,are investigated systematically with diagnostic analysis methods over a latitude belt between 80°N and 60°S.Also,the probable reasons for the existence of the source and sink of low frequency kinetic energy(LFKE) are discussed preliminarily.Results show that the horizontal distribution of the sources and sinks of kinetic energy of atmospheric 30-60 day oscillation is extremely different.The significant sources and sinks of LFKE mainly exist in the oceans and the coastal regions of continents or islands in the mid-high latitudes.It is also found that,in the vertical direction,the sources and sinks of kinetic energy of 30-60 day oscillation display barotropic structure in the mid-high latitudes of both hemispheres,but dispaly baroclinic structure in the equtorial region,and in the horizontal direction,the sources and sinks mainly display zonal wave-like distribution.The source and sink of LFKE are determinded by ageostrophic wind effect,frictional effect,interaction between sub-grid-scale systems,nonlinear interaction,and the flux-divergence of LFKE transported by transient wind.There are some regional reasons for the generation of sources and sinks which are not completely identical in different areas.     

台风内核与外围能量发展的物理因子

利用Ａｎｔｈｅｓ关于台风的区域划分以及物理量特征尺度的结果，采用尺度分析方法导出了台风不同区域的控制方程组，又用ＷＫＢ方法得到各区的波能量方程并进行了讨论。指出影响台风发展的物理因子在各区的异同点：各区都有非定常因子；同时，台风内核及外围中层对流层的因子有涡度和切向风的垂直变化，外围边界层有热成风及其偏差，外围流出层有水平位温梯度，这些因子与重力波适当的移向相配合，可使台风能量发展，强度增大。     

北半球中高纬月平均环流正压斜压动能的年变化特征

本文利用多年月平均资料计算了北半球中高纬月平均环流正压、斜压动能的年变化特征。结果表明无论正压、斜压动能都具有明显的年变化,而且两者的变化趋势也是一致的,但是正压动能要比斜压动能对总动能的贡献大得多。环流异常具有相当正压的垂直结构。有关结论可为长期数值预报模式的简化提供依据。     

THE DEVELOPMENT OF SYMMETRIC DISTURBANCE SUPERPOSED ON BAROCLINIC FRONTAL ZONE UNDER THE ACTION OF DEFORMATION FIELD*

The development of symmetric disturbance superposed on the background field of Hoskins-Bretherton (1972) frontogenesis model is investigated by means of WKBJ approach,It is found that the forcing of large-scale deformation,the frontal circulation and the spatial-temporal variations of stability parameters (F²,N²,M²) can bring about the development of symmetric disturbance,even though the frontal baroclinic flow is symmetric stable (F²N²-M²>0),The frontogenetical process of deformation confluence zone and the ascending branch of frontal circulation are in favor of the development of symmetric disturbance,The actions of ageostrophic shear in frontal zone and the variation of stability parameters are dependent on the structure of disturbance.