High time resolution monitoring of tropospheric temperature with a Radio Acoustic Sounding System (RASS)     

T. Tsuda  Y. Masuda  H. Inuki  K. Takahashi  T. Takami  T. Sato  S. Fukao  S. Kato 《Pure and Applied Geophysics》1989,130(2-3):497-507

We have observed the time-height variation of the temperature field in the upper troposphere using a Radio Acoustic Sounding System (RASS) which consists of the MU radar and a high-power acoustic transmitter. The fast beam steerability of the MU radar has made it possible to measure temperature profiles in a fairly wide height range in the upper troposphere (5–11 km), even under intense wind conditions. Observations were continued for about 32 hr on 24–26 December, 1986 with a time-height resolution of 30 min and 150 m. During the observation period, the tropospheric jet was so intense that the acoustic wavefronts were severely distorted. Using wind velocity profiles observed by the MU radar we have numerically estimated the propagation of acoustic wavefronts, and further determined favorable pointing directions for the MU radar to receive significant backscattering from refractive index fluctuations produced by the acoustic waves. Conventional radiosonde soundings were carried out every 6 hr, which showed a temperature decrease of 4 K/day in the upper troposphere during the observation period. Temperature profiles taken by RASS agree well with the radiosonde results.  相似文献   

Estimation of flow enhancement in the Kinneret watershed due to cloud seeding     

A. Ben-Zvi  M. Langerman 《Stochastic Environmental Research and Risk Assessment (SERRA)》1989,3(3):203-216

A comparison is carried out between historical records of the flow measured in Kinneret watershed during and prior to the time of cloud seeding for rainfall enhancement. Precipitation series for the control area of the meteorological experimentation serve as a reference for the comparison. The fluctuations of the flow, which would have occurred unless the effect of the seeding, are estimated by a linear regression on the precipitation as the control. The regression parameters are calibrated separately for the unseeded and for the seeded time series. The model with the parameters calibrated for the unseeded series is applied on the rainfall recorded during the seeded time, and vice versa. The difference between the measured and the computed data is attributed to the effect of cloud seeding. Similar comparisons are carried out with respect to rainfall series recorded at the target area and at the edge of the enhanced area.The results indicate that the flow from the affected sector of the watershed has been enhanced, with respect to the control, by 31×10⁶ m ³/year, at a significance level of 31. This enhancement is 5% of the volume which is generated in that area. The rates found with respect to the rainfall at the edge are higher than those found with respect to the control, while those with respect to the rainfall at the center of the target area are lower.  相似文献   

云、雨水酸度和离子浓度与其微物理参数的关系   总被引：3，自引：0，他引：3       下载免费PDF全文

刘奇俊  丁国安  汤洁  房秀梅  吴凡  苏维瀚 《气象学报》1993,51(2):195-202

本文1987年5-6月和1989年5-6月庐山地区的实测资料,分析了云、雨水酸度和离子浓度与其微物理量间的关系。结果表明,云、雨滴大小、含水量、谱宽等微物理量的演变直接影响着其酸度和离子浓度。  相似文献   

探地雷达图像的正演合成与偏移处理   总被引：8，自引：2，他引：8  

邓世坤  王惠濂 《地球物理学报》1993,36(4):528-536

本文讨论了射线追踪法实现二维地电断面的探地雷达图像的正演合成问题,其中包括二维地电断面的数字拟合、多层连续界面介质中高频电磁波的反射与透射统一的运动学边界方程;根据Huygen's-Fresnel原理导出了均匀介质中二维管状体模型的衍射雷达波的计算公式;给出了用射线追踪法合成的二维地电模型的探地雷达图像;用衍射波公式合成了二维管状模型的雷达图像,并与物理模拟作了比较.在此基础上,用Kirchhoff积分法对数字模拟与物理模拟记录的雷达图像作了偏移处理,并给出了实例.  相似文献   

Rainfall estimation using raingages and radar — A Bayesian approach: 1. Derivation of estimators     

D. -J. Seo  J. A. Smith 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(1):17-29

Procedures for estimating rainfall from radar and raingage observations are constructed in a Bayesian framework. Given that the number of raingage measurements is typically very small, mean and variance of gage rainfall are treated as uncertain parameters. Under the assumption that log gage rainfall and log radar rainfall are jointly multivariate normal, the estimation problem is equivalent to lognormal co-kriging with uncertain mean and variance of the gage rainfall field.The posterior distribution is obtained under the assumption that the prior for the mean and inverse of the variance of log gage rainfall is normal-gamma 2. Estimate and estimation variance do not have closed-form expressions, but can be easily evaluated by numerically integrating two single integrals. To reduce computational burden associated with evaluating sufficient statistics for the likelihood function, an approximate form of parameter updating is given. Also, as a further approximation, the parameters are updated using raingage measurements only, yielding closed-form expressions for estimate and estimation variance in the Gaussian domain.With a reduction in the number of radar rainfall data in constructing covariance matrices, computational requirements for the estimation procedures are not significantly greater than those for simple co-kriging. Given their generality, the estimation procedures constructed in this work are considered to be applicable in various estimation problems involving an undersampled main variable and a densely sampled auxiliary variable.  相似文献   

A TECHNIQUE TO RECOGNIZE AND ESTIMATE SEVERE STORM BY USING SINGLE DOPPLER WEATHER RADAR   总被引：1，自引：0，他引：1       下载免费PDF全文

Zhang Pengfei  Ge Runsheng  Liu Enqing 《Acta Meteorologica Sinica》1991,5(3):274-284

Using single Doppler weather radar echo information, this paper presents a technique for recognizing two-di-mensional flow field structure of the severe storm and estimating the divergence, the vorticity, and the intensityof wind shear line, and gives some examples.  相似文献   

SAR图像纠正的数学模型   总被引：3，自引：0，他引：3  

肖国超 《测绘学院学报》1994,(3)

本文对Ｇ．Ｋｏｎｅｃｎｙ等提出的平距投影的合成孔径雷达（ＳＡＲ）图像纠正的数学模型给子证明，并指出其近似性。随后推导了斜距投影的雷达图像纠正的数学模型，且以雷达图像的模拟数据，验证了该数学模型与Ｇ．Ｋｏｎｅｃｎｙ的数学模型具有相同的数学精度。  相似文献   

多卜勒雷达经向速度资料的预处理方法     

周建芬  周文贤 《南京气象学院学报》1994,17(2):213-218

利用变分法原理提出了对雷达速度资料进行预处理的一种方法，数值试验表明该法能有效地消除雷达速度资料中的小尺度运动径向速度分量及“噪声”。  相似文献   

ERROR COMPARISON OF WIND FIELD RETRIEVAL FROM SINGLE AND DUAL-DOPPLER RADAR OBSERVATIONS          下载免费PDF全文

Tao Zuyu 《Acta Meteorologica Sinica》1994,8(3):337-345

The error distributions of the wind fields retrieved from single and dual-Doppler radar observations are given inthis paper.The results indicate that the error of dual-Doppler retrieval depends on the position in the scan region of thedual-Doppler radar.The error of single-Doppler retrieval by using velocity azimuth processing(VAP)technique de-pends on the angle between the directions of wind and the radar beam.Generally,the winds retrieved from single Doppl-er radar are close to those retrieved from dual-Doppler radar.But,the error distribution of the single-Doppler retrievalis different from the dual-Doppler retrieval.We simulate the retrievals of single Doppler observation by the use of theoutput wind data from a 3-D numerical model of severe convection.The comparison of the simulated single-anddual-Doppler retrievals shows that the VAP may be a suitable technique for the operational analysis of mesoscale windfields.It can also be used as a supplement to wind field retrieval in the field experiment.  相似文献   

青藏高原地区云对地面有效辐射的影响：Ⅱ.强迫作用   总被引：2，自引：0，他引：2  

王可丽  钟强 《高原气象》1994,13(2):128-134

本文利用１９８２年８月－１９８３年７月青藏高原地面热源观测试验资料，讨论了与云对地面有效辐射强迫作用有关的参数的计算问题，并对这些参数的计算结果进行了分析。结果表明：晴空、全云条件下的地面有效辐射和云对地面有效辐射强迫作用的年平均日变化振幅有明显的地域差异；云对地面有效辐射的强迫作用春夏大，秋冬小，甘孜、拉萨、那曲和改则４站平均的年平均值为－２７．２Ｗ／ｍ＾２。?  相似文献