THE STUDY OF HIGH EFFICIENT AgI PYROTECHNICS AND THEIR NUCLEATING PROPERTIES*

Two kinds of high efficient Agl pyrotechnics BR-88-5 and BR-91-Y have been developed.The tests in the cloud chamber show that the AgI ice nucleating effectiveness can reach up to 10¹⁵/g,and the BR-91-Y has even higher ice nucleating rate.Two kinds of foreign AgI pyrotechnics have been made according to the given formulations and also tested in the cloud chamber for comparison.X-ray diffraction analysis for the aerosols produced by burning BR-91-Y shows that AgI in acrosols still retains the hexagonal crystal form and the lattice parameters are smaller than those of pure AgI and other AgI composite nuclei,and closer to ice.Combining with the other tests,the reasons for the high efficiency of BR-91-Y have been discussed.     

高效碘化银焰火剂及其成冰性能的研究

介绍了新研制的两种高效碘化银焰剂ＢＲ－８８－５和ＢＲ－９１－Ｙ。据云室检测，它们的成核率在—７．５——２０℃时均可达到１０１５／ｇＡｇＩ，其中ＢＲ－９１－Ｙ焰剂具有更高的核化速率。两种按国外配方制作的焰剂也在同样条件下进行了测试对比。对焰剂燃烧产生的气溶胶作了物理化学性质检测，Ｘ光衍射分析表明，ＢＲ－９１－Ｙ焰剂产生的气溶胶中ＡｇＩ仍然保持六方晶系，其点阵参数比ＡｇＩ本身及其他ＡｇＩ复合核更接近于冰。结合其他检测，讨论了新焰剂具有优良性能的原因。     

含AgI焰剂成冰性能与物化特征的实验研究

利用CAMS的1 m~3等温云室系统筛选出新型高效AgI焰剂WMC-IN-001和WMG-IN-002。检测结果表明,它们具有较高的成核率,在-15℃时达到10~(15)g~(-1)AgI量级,尤其在-7℃时WMC-IN-001的成核率仍可达到10~(14)g~(-1)AgI量级。同时给出对节银剂配方和2011年市场上主要的几种催化剂的检测结果进行对比。WMC-IN-001和WMC-IN-002的成冰速率较慢,在各检测温度的成冰速率差异较小,均在40~55 min。利用冷场发射扫描电镜和能谱仪对WMC-IN-001燃烧产生的气溶胶粒子作了物化特征分析,粒子分布在0.02~0.60μm,具有两个典型的模态:0.02~0.10μm的较小的粒子和0.20~0.55μm的较大的粒子,均立方直径为0.2472μm。WMC-IN-001气溶胶粒子明显偏大,小粒子相对较少,这可能是其成冰速率偏慢的原因之一。     

贺兰山地区大气冰核浓度的测量及初步分析

根据 1 994年在银川和阿拉善左旗观测得到的冰核资料 ,给出了两地不同天气条件下的大气冰核浓度 ,分析并讨论了冰核浓度与风、降水、天空状况等的关系 ,给出了飞机在空中测量冰核的结果。     

STUDY OF THE RELATIONSHIP BETWEEN IWC AND Z FOR NONSPHERICAL ICE PARTICLES AT MILLIMETER WAVELENGTH

Ice water content (IWC) plays important roles in weather and climate change. Determining the IWCs of cirrus clouds with millimeter-wavelength radar can be problematic due to influences of ice particle rotation on their backscattering cross sections. We here introduce models to describe the radiation patterns of six nonspherical particles of specific sizes. Simulations using HFSS software were applied to describe the differences resulting from different orientations and equivalent spheres. A double exponential function was used for fitting to describe the relationship between the particles’ maximum sizes and backscattering cross sections. The backscattering cross sections of nonspherical ice particles were computed by the method of moment, and those of the equivalent spherical particles were computed by Lorenz-Mie theory for three different orientations: fixed, horizontal, and random. Assuming that a mixture of nonspherical ice particles follows the B-H mixing model, the size distribution of cirrus particles obeys the exponential distribution measured by NASA in 2007. By computing the IWCs of cirrus clouds, which follows the above mentioned B-H model and exponential distribution, the radar reflectivity factors of nonspherical ice particles and equivalent spheres at three different orientations can be computed. Subsequently, the IWC results can be acquired by inputting the radar reflectivity variables into the well-known IWC-Z formula. The analysis described here demonstrates that when using the radar reflectivity Z, the orientation must be considered in order to determine the IWC. Using equivalent sphere theory, the derived IWCs underestimate the actual IWCs. These results are important for accurately retrieving the microphysical parameters of cirrus clouds.     

对流参数在强对流天气潜势预测中的作用

文章结合强对流天气发生发展的物理机制，介绍了与浮力能和风切变有关的几个对流参数的物理概念和计算方法，并结合具体个例分析了这些参数在强对流天气潜势预测中的作用。     

THE CHARACTERISTICS OF HIGH WIND DISTRIBUTION IN CHINA'S COASTAL REGION AND THEIR CAUSES

This work investigates the distribution of high winds above Beaufort scale 6 in the offshore zones of China using high-resolution satellite measurements.A numerical experiment is carried out in order to find out the effects of Taiwan Island on the formation of strong winds.The analysis indicates that the distribution of high wind occurrence is similar to that of the average wind velocity in winter.High winds tend to be anchored in special topographical regions,such as the Taiwan Strait,the Bashi Channel and the southeast coast of Vietnam.High winds occur much more frequently over the warmer than the colder flank of Kuroshio front as it meanders from Taiwan to Japan.The frequency of high winds decreases drastically in spring.The Taiwan Strait maintains the largest high wind occurrence.Besides,high winds remain frequent in the Bashi Channel,the southeast tip of Taiwan Island and the warmer flank of Kuroshio front.In summer,high winds generally occur infrequently except over a broad region off the southeast coast of Vietnam near 10°N and the frequency there decreases from southwest to northeast.High winds around Taiwan Island present near axisymmetric distribution with larger frequency along southeast-northwest direction and smaller frequency along southwest-northeast direction.The dominant direction of high winds exhibits a counterclockwise circulation surrounding the island.The frequency of high winds increases rapidly in autumn and almost repeats the distribution that appears in winter.The simulation results suggest that the effects of Taiwan Island topography on high winds vary with seasons.In winter,topography is the major cause of high winds in the surrounding oceanic zones.High winds in both Taiwan Strait and the southeast corner of the island disappear and the frequency decreases gradually from south to north when the terrain is removed.However,in summer,high wind frequency derived from two simulations with and without terrain is almost identical.We attribute this phenomenon to the factors which are responsible for the formation of high winds.     

夏季西太平洋副热带高压北跳及异常的研究

根据欧洲中心1980～1989年逐日200,500和850hPa风场、高度场及日本气象厅提供的GMS观测的黑体辐射温度（TBB）逐日资料,探讨了夏季西太平洋地区（125～145°E）副热带高压脊线季节性北跳、季内脊线位置的异常与低纬度的西风爆发和热带对流的关系。研究表明：初夏西太平洋地区低层赤道西风爆发后,西太平洋地区的赤道对流加强（赤道地区的TBB值减小）;赤道西风向北扩展,赤道强对流向北推移,热带对流加强（热带地区TBB值减小）。夏季西太平洋副热带高压脊线的二次北跳现象与低层赤道西风二次北跳及赤道对流向北推移密切相关。研究指出：夏季热带对流弱（强）,西太平洋副热带高压脊线位置相对偏南（北）,夏季西太平洋副热带高压脊线位置的异常与高、低层流场辐合、福散中心的位置及高层西风传播方向有关。     

FURTHER STUDY ON THE PROPERTIES OF OPERATORS OF ATMOSPHERIC EQUATIONS AND THE EXISTENCE OF ATTRACTOR

The equivalent operator equation is derived from the full primitive nonlinear equations of theatmospheric motion and the properties and physical senses of the operators are studied.In theinfinite dimensional Hilbert space,the global asymptotic behavior of the atmosphere system withthe non-stationary external forcing is studied under the assumption of the bounded externalforcing.The existence theorems of the global absorbing set and the global attractor are obtained.Thus,the conclusions deduced from the large-scale atmosphere(Li and Chou 1996 a;1996 b)areextended to the general atmosphere.     

PHYSICAL PROPERTIES OF THE SYMMETRIC AND ANTISYMMETRIC MOTIONS AND RELATED ENERGY CONVERSION

The physical properties of the symmetric and antisymmetric motions,such as the conservation of the ab-solute angular momentum,the mutual conversions between various forms of energy,have been analysed by usingthe sets of equaticns in p-coordinates controlling the motions in the primitive equation model atmosphere.Theresults show that only the symmetric component of zoral geopotential difference caused by orography and thatof the zonal frictional torque,have contribution to the change of the global angular momentum,and that themutual conversions between various forms of energy,in addition to those similar to the results in the classical case,irclude those associated with the symmetric and antisymmetric motions.     

STUDY ON THE MAIN CLIMATE MODES OF SHANDONG PRECIPITATION AND THEIR RELATIONS WITH THE EAST ASIAN WESTERLY JET

Summer precipitation patterns of Shandong Province are relatively independent with regard to the whole eastern China region.To study the rules and causes of precipitation variations,three main climate modes-on the annual,seasonal,and climatic intra-seasonal oscillation(CISO) scales-are extracted using a harmonic analysis method based on daily precipitation of Shandong during 1965-2009 and multi-year averaged pentad precipitation at 722 stations in China during 1971-2000.Among the three precipitation climate modes,the annual mode is closely related to the annual cycle of Earth-Atmosphere thermal system,which is characterized by the periodic dry and wet seasons.The seasonal mode reflects the monsoon effect on precipitation and the main flood season’s contribution to annual precipitation variations.As an important climatic signal,the CISO mode is more evident during summer monsoon.The gradual modulations of the CISO mode,seasonal mode,and annual mode control the annual variation of precipitation.To study the relationship between precipitation climate modes and atmospheric circulations,an East Asian Westerly Jet Index(EAWJI) is defined in this paper.It is revealed that precipitation of Shandong is closely related to EAWJI in all climate modes.A wet or dry phase of each climate mode corresponds to a specific atmospheric circulation pattern.The phase of the annual mode is reverse to that of EAWJI.During the wet phase of the seasonal mode(weak phase of EAWJI),the atmospheric circulation in and around Shandong is characterized by upper-level divergence and low-level convergence.A reversed atmospheric circulation exists for the dry phase(strong phase for EAWJI).In the summer wet phase of CISO mode(strong phase of EAWJI),Shandong is controlled by upper-level divergence and low-level convergence.Again,the dry phase is corresponding to a reversed circulation structure.The methodology employed in this research,i.e.studying the precipitation climatic variations in terms of independent components of different temporal scales,provides a new approach for annual and seasonal precipitation prediction.     

THERMODYNAMIC PROPERTIES AND ROLE OF THERMALS IN THE STRATUS-TOPPED BOUNDARY LAYER

From results of two large-eddy simulation of stratus-topped boundary layer,the structure,thermodynamic prop-erties and role of thermals are investigated by using conditional sampling methods,which divided the thermals into thewarm/moist,cool/dry,warm/dry and cool/moist events.The results show that the main turbulent circulation in thestratus-topped boundary layer is composed of the warm/moist updraft and cool/dry downdraft.Below entrainmentregion,the warm/moist updrafts and cool/dry downdrafts are,respectively,positively and negatively buoyant andcontribute most to total fluxes and variances.Evaporative cooling has important effect on the structure and thermodynamic properties of thermals instratus-topped boundary layer.     

海温和极冰对副热带高压季节性北跳影响的数值模拟

道德以南海区域平均的候平均ＯＬＲ值下降至２３５Ｗ／ｍ,同时纬向风由东转成西为定义标准确定南海季风从１９７９到１９９４年间爆发的平均日期是５月第４候,然后对１６年的ＯＬＲ场,风场及θＸ场的时段叠加合成图进行了分析,认为南海夏季风的建立是南海－西太平洋系统所造成。     

我国东部主要城市夏季高温气候特征及预测

利用我国东部地区1961～2002年夏季(6～8月)高温资料，探讨了上述地区主要城市高温气候特征，建立该地区高温及强高温过程较完整的时间序列。分析我国东部地区石家庄、南京、福州等12城市夏季高温气候特征。观测结果表明，石家庄测站强高温过程期间干热和闷热天气持续时间不长，极端气温高、日平均风速小、日平均相对湿度小；南京和福州测站强高温过程期间闷热天气持续时间长，极端气温高、日平均风速小、日平均相对湿度大。近年来夏季月平均日照时数在减少。东亚副热带高压和大陆变性高压是造成我国东部地区城市夏季高温的主要影响系统，强盛并持续副热带高压和大陆变性高压控制是我国东部地区高温日数和强高温过程偏多的主要原因。在此基础上用均生函数——最佳子回归集建立月气候预测模型，能较好地预测夏季月高温日数，预测误差不大，预测模型具有一定的稳定性，有应用价值。     

影响中国台风的气候特征及其与环境场关系的研究

分析了影响中国台风的气候特征,结果表明：5-11月是影响台风活跃季节,7-9月为集中期;1951—2004年影响台风的频数变化呈减少趋势,1970年代后期明显减少,近十年是影响台风频数最少的时期;近50余年影响台风中超强台风的频数减少显著;台风生成的源地有明显的年代际变化,1960年代-1970年代生成台风位置偏东、偏南,1980年代以后转为偏北、偏西。同时分析了影响台风与北太平洋海温及东亚夏季风环流的关系,认为北太平洋海温的年代际和年际变化与影响台风关系密切;影响台风偏多年和偏少年,其环流形势截然不同。     

STUDY ON CLIMATIC CHARACTERISTICS OF CHINA-INFLUENCING TYPHOONS AND THE INTERRELATIONS BETWEEN THEM AND THEIR ENVIRONMENTAL FACTORS

Climatic characteristics of China-influencing typhoons (CIT) were analyzed in this paper. Main characteristics include: (1) CIT season is May-November, especially from July to September. (2) Frequency of the CIT shows a decreasing trend during 1951-2004, especially after the late period of the 1960s. (3)Strong CIT also shows an obvious decreasing trend. Meanwhile, there exist obvious interdecadal variations in the CIT genesis, being more southward and eastward than normal in 1960s-1970s, and more northward and westward than normal in the 1980s. In addition, the interrelations between CIT and its environmental factors show that CIT has close relationships with sea surface temperature and East Asian summer monsoon; the structure of the circulations in frequent CIT years is much different from that in infrequent CIT years.     

南亚高压在平流层的特征及ENSO影响的进一步研究

为了搞清南亚高压在平流层的结构特征以及ENSO事件对它的影响，用较长时段的ECMWF再分析资料对南亚高压在平流层的结构特征进行了系统的分析研究，结果表明：南亚高压在垂直方向上最高只在平流层的低层存在，系统的最强出现在150 hPa高度附近，50 hPa以上高压及相应的反气旋环流已经消失；高压系统随着高度增加有略向西北方向倾斜的特征。在El Ni?o年和La Ni?a年南亚高压在平流层无论是位势高度场还是流场都有明显不同的异常变化，表明ENSO对南亚高压在平流层的结构有一定的影响，一般是El Ni?o时对应为较弱的南亚高压，而La Ni?a时对应略微偏强的南亚高压。     

A THEORETICAL STUDY ON THE MULTIPLE EQUILIBRIA OF TROPICAL ATMOSPHERE AND THEIR RELATION TO THE ONSET OF THE SUMMER MONSOON

Multiple equilibria and their stability in tropical atmosphere are investigated through β-plane barotropic models with consideration of heating and dissipation. We have derived the solutions of the model equations corresponding to the multiple equilibria or the steady flows first, and then establish the criteria for the stability of steady flow by use of the Liapunov direct Method. When these criteria are applied to the solutions of equilibria obtained, stable flows, which are closely related to the different patterns of quasi-stationary circulation in the tropical region, are found. The configurations of these stable flows and the shift between two of them as season changes provide quite reasonable explanations to many fundamental problems of tropical circulation features such as the catastrophe mechanism of the onset and the break-active cycle of the Asian summer monsoon. It follows that the onset or the abrupt transition of the Asian summer monsoon could be attributed to the multiple equilibrium property of the tropical circulation resulted from the advective nonlinearity, which provide another explanation among others.     

FURTHER STUDY ON THE PROPERTIES OF OPERATORS OF ATMOSPHERIC EQUATIONS AND THE EXISTENCE OF ATTRACTOR*

The equivalent operator equation is derived from the full primitive nonlinear equations of the atmospheric motion and the properties and physical senses of the operators are studied.In the infinite dimensional Hilbert space,the global asymptotic behavior of the atmosphere system with the non-stationary external forcing is studied under the assumption of the bounded external forcing.The existence theorems of the global absorbing set and the global attractor are obtained.Thus,the conclusions deduced from the large-scale atmosphere(Li and Chou 1996a;1996b) are extended to the general atmosphere.