GBPP－100型地面雨滴谱仪测量的可靠性

用ＧＢＰＰ－１００型地面雨滴谱仪与吸水纸斑，点法进行同步观测，对比分析ＧＢＰＰ－１００型地面雨滴谱仪测量的可靠性。结果表明：（１）两种方法测量雨滴谱所得资料除平均直径、均立方根直径相似性稍差外，其它特征量的线性相关显著性水平均为０．００５；（２）两种方法所得雨滴谱资料除平均直径、均立方根直径、降水强度稍有差异外，其它特征量均无显著差异。     

GBPP—100型地面雨滴谱仪测量的可靠性

用ＧＢＰＰ－１００型地面雨滴谱仪与吸水纸斑点法进行同步观测，对比分析ＧＢＰＰ－１００型地面雨滴谱仪测量的可靠性。结果表明：（１）两种方法测量雨滴谱所得资料除平均直径、均立方根直径相似性稍差外，其它特征量的线性相关显著性水平均为０．００５；（２）两种方法所得雨滴谱资料除平均直径、均立方根直径、降水强度稍有差异外，其它特征量均无显著差异。     

气溶胶粒子的降水清除

讨论了雨滴在云下对气溶胶粒子的清除,考虑了气溶胶粒子和雨滴之间的碰并系数,雨滴谱以及气溶胶粒子谱对清除系数的影响。在０１＜ ｒ＜ １０ μｍ 范围内,利用不同的碰并系数表达式算得的降雨对该区间内气溶胶粒子的清除系数相差很大,但对总质量清除系数影响不大;雨滴谱的改变对总质量清除系数有很大影响;不同的气溶胶粒子谱对总质量清除也有一定影响。雨滴谱用Ｍａｒｓｈａｌｌ－ Ｐａｌｍ ｅｒ 分布;气溶胶粒子谱用Ｊｕｎｇｅ 分布ｎ（ｒ）＝ ａｒｂ 算得清除系数与雨强关系为Λ＝ ０５１Ｉ０７８,而气溶胶粒子谱改用三参数分布（ｒ）＝ ａｒｂｅ－ ｃｒ得到清除系数与雨强的关系为Λ＝ ０２５Ｉ０７７。     

暴雨微物理结构特征

本文根据长春一次大暴雨雨滴谱资料的统计分析,给出了大暴雨雨滴谱分布、过程降水量的演变、微物理特征量、雨滴最大直径、优势直径、雨强、浓度、雨水含水量、雷达反射因子、雨滴吸收系数、衰减系数、雨滴动能等,以及这些特征量与雨强之间的关系式。     

地面雨滴谱观测与分析研究进展

雨滴谱是雨滴数浓度随其尺度变化的函数,是降水最基本的微物理特征量,对雨滴谱进行观测是研究云雾降水微观物理特征的重要途径之一。文章主要回顾了20世纪60年代以来,中国开展雨滴谱研究中常用的观测方法、观测仪器以及在谱特征参量、雨滴下落末速度、雨滴谱拟合等方面所做的一些工作和取得的重要成果。在探讨雨滴谱研究现状的基础上,提出了需要进一步研究的方向。     

银川平原一次中雨过程的雨滴谱及Z—I关系的个例分析

文献（＊1－6）中，大多从宏观及天气尺度的方面讨论了云带、雨带及降水的整个体系过程。而本文利用银川平原一次中雨过程的雨滴谱及Z－1关系的个例分析，从微观结构演变过程的角度，分析和探讨了雨滴谱的特征量与各种云类型下降水之间的关系。     

哈尔滨地区层状云降水微物理特征

利用GBPP－100型地面雨滴谱仪在哈尔滨地区所获得的春夏季降水雨滴谱资料，分析了哈尔滨地区层状云降水的雨滴谱分布、微物理参量及其起伏特征。     

哈尔滨地区积雨云降水微结构特征

1999年5－7月，采用PMS公司生产的GBPP－100型地面雨滴谱仪，对哈尔滨地区各镒降水过程进行了观测。本文对其中的7次雷雨过程进行重点分析，得到积雨云降水的雨滴谱分布、微结构以及起伏特征等一些有意义的结果。     

一次北上台风降水微结构演变特征

本文利用ＧＢＰＰ－１００型地面雨滴仪在沈阳夏季测得的一次台风过程降水资料，分析了台风雨滴谱的谱型、微结构参量及其演变特征。     

利用雨滴谱资料估算郑州地区雨强

应用染色泸纸法,采集不同降水类型雨滴谱资料,经统计,得出３种不同雨型下的Ｚ－Ｉ关系式,经检验,３种Ｚ－Ｉ关系式估算的郑州地区的雨强与实测雨量接近。     

低纬度超长波的统计特征

本文用1951年1月—1980年12月、20°N、500hPa高度距平资料,对频率域内的超长波谱密度作了计算。结果表明超长波的功率谱在40个月周期附近出现极值,特别是波数1。为了对比超长波和长波间的不同特征,对纬向波k=5-8的谱密度也作了计算,纬向波数k=5-8的谱密度是属白噪音时间序列随机过程。      

Saharan dust absorption and refractive index from aircraft-based observations during SAMUM 2006

During the Saharan Mineral Dust Experiment (SAMUM) conducted in summer 2006 in southeast Morocco, the complex refractive index of desert dust was determined from airborne measurements of particle size distributions and aerosol absorption coefficients at three different wavelengths in the blue (467 nm), green (530 nm) and red (660 nm) spectral regions. The vertical structure of the dust layers was analysed by an airborne high spectral resolution lidar (HSRL). The origin of the investigated dust layers was estimated from trajectory analyses, combined with Meteosat 2nd Generation (MSG) scenes and wind field data analyses. The real part n of the dust refractive index was found almost constant with values between 1.55 and 1.56, independent of the wavelength. The values of the imaginary part k varied between the blue and red spectral regions by a factor of three to ten depending on the dust source region. Absolute values of k ranged from 3.1 × 10⁻³ to 5.2 × 10⁻³ at 450 nm and from 0.3 × 10⁻³ to 2.5 × 10⁻³ at 700 nm. Groupings of k values could be attributed to different source regions.     

Radiative Effects on Temperature in the Stable Surface Layer

The interaction between longwave radiation and temperature fluctuations plays a role in the dissipation of temperature variance. This interaction is most easily described by spectral models of atmospheric turbulence and a spectral radiative dissipation function which gives the intensity of the damping at each radiative wavelength and wavenumber k. We have used a Corrsin–Pao closure for the spectral budgets of turbulent kinetic energy and temperature to study the coupling of radiation to turbulence. The spectral radiative dissipation function and a related integral have been fitted by analytical approximations with the correct asymptotic behavior. This resulted in a simple analytical formula for the dimensionless temperature spectrum as a function of Monin-Obukhov stability, and a new dimensionless parameter describing the relative importance of radiation in the temperature spectral budget. The radiative effects both on the temperature spectrum and on the dimensionless temperature variance can then be calculated. Based on typical values of the radiative dimensionless parameters for the surface layer, we conclude that radiative dissipation is probably negligible there.     

Interrelationships between atmospheric turbidity,the diffusely reflected visible radiation at the top of the earth's atmosphere and the global solar radiation at the surface

Summary The flux of radiation emerging at the top and bottom of a realistic model of a cloud-free, plane-parallel, vertically inhomogeneous turbid atmosphere has been computed for different values of atmospheric turbidity and surface albedo in 83 unequal spectral intervals over the short-wave or solar radiation (0.285–2.5 m) regime. These computations have been utilized to determine the diffusely reflected radiation at the top of the atmosphere in the spectral interval 0.535–0.7035 m (which covers the visible channels of the radiometers onboard the Geosynchronous Operational Environmental Satellites and the NOAA polar orbiting satellites) and in the spectral interval 0.375–0.7035 m. The total global solar radiation (0.285–2.5 m) reaching the surface has also been determined. Simple linear regression relationships have been established between (i) the reflected radiation at the top and atmospheric turbidity and (ii) between the global radiation at the surface and the reflected radiation at the top. These regression relationships yield coefficients of determination very close to unity. The implications of this strong linear dependence of the reflected radiation on atmospheric turbidity and of the global radiation at the surface on the reflected radiation at the top to satellite-based studies of the feasibility of estimation of the insolation (global radiation) at the surface are briefly mentioned.With 3 Figures     

中国飞机积冰的气候特征

本文利用美国国家环境预报中心（NCP）和国家大气研究中心（NCAR）联合处理的全球大气40年（1958－1997）资料，对近40年中国飞机积冰的气候特征进行了分析，通过功率谱及交叉谱分析的方法对南京地区的飞机积冰发生频率进行了周期变化的分析，并利用k均值法进行了飞机积冰的航空气候区划，给出了飞机积冰的时空分布特征。     

Some limitations to measurements of turbulence micro-structure with hot and cold wires

Some of the problems associated with measurements of the small-scale characteristics of dynamic and thermal fully developed turbulence are considered in the context of a study of the tendency-towards-isotropy assumption, Taylor's hypothesis, and internal intermittency, taking advantage of the possibilities offered by the I.M.S.T. Air-Sea Interaction Simulation Tunnel. The paper reviews and discusses the choices of probes and operating parameters for hot-wire anemometers and cold-wire thermometers. A detailed study of the most important characteristic, the spectral signal-to-noise ratio, is presented. Problems specific to measurements with several wires are studied, especially the true resolution of one-point multi-wire probes and the errors due to calibration uncertainties for two-point measurements. Serious doubts are raised on the validity of gradient-probe data.     

In-water and remote measurements of ocean color

Spectral measurements of downwelling irradiance, E _d(), above the surface, and of upwelling irradiance just below the surface, E _u(), allow computation of spectral values of the diffuse reflectance R() = E _u()/E _d(); this yields full information about the true color and brightness of the ocean. Typical results are presented and interpreted for waters very different in turbidity and phytoplankton content. Conversely, the possibility of infering the water content from R() data at selected wavelengths is examined in terms of the respective number of equations and unknowns. The necessary use of assumptions and of empirical laws is emphasized.The magnitude of the useful signal emerging from the water, and the magnitude of the additional signals due to specular reflexion at the interface and to atmospheric scattering, are compared on the basis of spectroradiometric measurements performed within and above the sea, from different altitudes. These unwanted signals are dominant, causing a drastic change in the spectral composition of the light received by a remote sensor. The evaluation of the atmospheric effect must be very precise in order to recover the marine signal with a sufficient accuracy for a meaningful application of any kind of algorithm.This work was supported in part by the Centre National d'Exploitation des Océans (under contract CNEXO 77/1695) and in part by the Centre National de la Recherche Scientifique (RCP 247 & ERA 278).     

Intraseasonal zonal wind fluctuations seen through Indian radiosonde observations

Summary Twice-daily radiosonde records for Calcutta, Madras, Nagpur, New Delhi, Trivandrum, and Visakhapatnam have been quality checked and analyzed for intraseasonal activity in the summer monsoon. The records for all six cities end on 30 June 1978 and are 17–27 years long.Spectra were estimated by smoothing periodograms and by using the maximum entropy method (MEM), which entails fitting an autoregressive (AR) model. We show how confidence limits can be placed on an average of MEM spectral estimates using the Central Limit Theorem and how this helps pick the orders of the AR models to be tried. We donot favor use of Akaike's Final Prediction Error in choosing the model order, because it can grossly underestimate the AR model order needed to resolve low frequency peaks.MEM spectra of zonal wind based on thirtieth order AR models have large peaks around 30 day time scales. 10–20 day activity is identifiable but is much less prominent. On average, 3–5 day time scales are part of the spectral continuum and do not have a significant spectral peak.Time-height diagrams of filtered zonal wind show that a deep layer of the troposphere acts in phase on 30–50 day time scales over India. The shortest vertical length scale is over southern India and the longest is over northern India. Vertical phase propagation is irregular except over Nagpur, where it is generally upward. Empirical orthogonal functions indicate that vertically in phase activity has more variance (kinetic energy) than the first baroclinic mode.With 10 Figures     

Improved bora wind simulation using a nested Eta Model

Summary In connection with a number of recent publications on anomalous (excessive) absorption of shortwave radiation (SWR) by clouds, the data of aircraft observations of spectral and total SWR vertical profiles in the troposphere obtained within the CAENEX, GAAREX and FGGE programmes have been discussed. These data demonstrated persuasively the existence of substantial SWR absorption by clouds in the visible wavelength region. In this context, the results of simulation numerical medelling of the SWR transfer in clouds have been considered. These show a significant enhancement of the SWR absorption by clouds due to an increase of the mean free path of photons under an impact of multiple scattering in clouds. Another important consideration may be the impact of SWR-absorbing pollutants in clouds, especially soot aerosols.With 4 Figures     

Modelling velocity spectra in the lower part of the planetary boundary layer

Principles used when constructing models for velocity spectra are reviewed. Based upon data from the Kansas and Minnesota experiments, simple spectral models are set up for all velocity components in stable air at low heights, and for the vertical spectrum in unstable air through a larger part of the planetary boundary layer. Knowledge of the variation with stability of the (reduced) frequency % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaaccaGae8NKby% kaaa!37B5!\[f\] _m for the spectral maximum is utilized in this modelling. Stable spectra may be normalized so that they adhere to one curve only, irrespective of stability, and unstable w-spectra may also be normalized to fit one curve.The problem of using filtered velocity variances when modelling spectra is discussed. A simplified procedure to provide a first estimate of the filter effect is given.In stable, horizontal velocity spectra, there is often a gap at low frequencies. Using dimensional considerations and the spectral model previously derived, an expression for the gap frequency is found.