西太平洋热带海域强对流天气过程湍流通量输送的某些特征

本根据“实验３号”科学考察船在ＴＯＧＡ－ＣＯＡＲＥ（１９９２年１１月－１９９３年２月）定点（２°１５＇Ｓ，１５８°００＇Ｅ）连续观测的大气，海洋资料，利用考虑风速和大气层结影响的整体输送动力学公式，计算给出了在西太平洋热带海域强对流天气过程中动量、感热和潜热等湍流通量垂直交换和水平输送的一些特性，并与该海域其它天气过程湍流通量交换和输送的特性作了比较，此外，中还讨论了更接近实际的曳力系数，感热     

Effects of radiation models on the calculation of atmospheric infrared cooling rates

Effects of various radiation models and spectral data on the calculation of the atmospheric infrared cool-ing rates (IRCR) have been systematically investigated by contrasting with a model, whose accuracy of IR transmission function is comparable to that of exact line-by-line integration, as a reference model.     

地形暴雨的多普勒天气雷达观测分析

为了进一步揭示地形对暴雨的影响,提高强降水的预报、监测和预警能力,针对三次落区于太行山东部迎风坡的暴雨天气,通过对多普勒天气雷达的观测分析发现:三次暴雨均为积层混合型絮状回波,受太行山地形的影响,无论回波移动方向如何,在偏东风作用下,较强回波均在太行山东侧迎风坡加强(或有新生)、合并、移速减慢,对应降水加强;三次过程径向速度场均为连续的大尺度风场特征,低层均有偏东风"牛眼"出现并伴有风速辐合,"牛眼"的形成、强弱、面积的大小和维持时间的长短以及风向的变化对三次暴雨的形成至关重要。低层偏东风"牛眼"结构急流的存在为太行山迎风坡暴雨形成的判据。     

多普勒天气雷达资料与乡镇雨量资料的同步显示

通过对新一代多普勒天气雷达终端显示软件的更新和配置文件夹下数据信息的修改,可将河南省GPRS乡镇雨量监测网络系统建立的SQL雨量数据库中所有关键点的每分钟雨量值,实时叠加显示在雷达探测到的反射率产品中,实现反射率因子和降水率之间的直观对比,帮助业务人员准确使用雷达产品.     

陕西省林果业农用天气预报业务系统研究

利用模糊综合评判方法和专家打分法建立了套袋指数等5种农事活动和苹果等陕西10种主栽林果分生育期生长气象适宜度预报模型。在此基础上开发了基于g／s的陕西省林果业农用天气预报业务系统,实现了3d时效24h间隔的农事活动和林果生长气象适宜度预报自动计算与输出。     

毛乌素沙区近期春季气候变化趋势的探讨

本文根据毛乌素沙区鄂托克，东胜、盐池、榆林和乌审旗近40年的春委气象资料，讨论了与沙漠化过程有关因子的气候演变趋势。结果表明，在50年代后期和60年代春季，气候较湿；70年代春季变干；80年代春季变湿。假如这种准10年的气候振荡是客观存在的，那么90年代春季的气候将可能变干。通过对这些台站的春季降水量与春季干燥系数的时间序列的功率变分析，发现存在准3年和8－9年的周期，它可能与北半球冷空气活动及西太平洋副热高压环流的气候振荡有某种内在的联系。本文采用多元线性回归方法建立了降水量和干燥系数的预报模型。利用建国以来的实例讨论了人类对大自然的不同干预将会产生不同的气候效应。     

A hybrid calibration approach to Hertz-type contact parameters for discrete element models

This study aims at providing a hybrid calibration framework to estimate Hertz-type contact parameters (particle-scale shear modulus and Poisson ratio) for both two-dimensional and three-dimensional discrete element modelling (DEM). On the basis of statistically isotropic granular packings, a set of analytical formulae between macroscopic material parameters (Young modulus and Poisson ratio) and particle-scale Hertz-type contact parameters for granular systems are derived under small-strain isotropic stress conditions. However, the derived analytical solutions are only estimated values for general models. By viewing each DEM modelling as an implicit mathematical function taking the particle-level parameters as independent variables and employing the derived analytical solutions as the initial input parameters, an automatic iterative scheme is proposed to obtain the calibrated parameters with higher accuracies. Considering highly nonlinear features and discontinuities of the macro-micro relationship in Hertz-based discrete element models, the adaptive moment estimation algorithm is adopted in this study because of its capacity of dealing with noise gradients of cost functions. The proposed method is validated with several numerical cases including randomly distributed monodisperse and polydisperse packings. Noticeable improvements in terms of calibration efficiency and accuracy have been made.     

The phase relation between sunspot numbers and soft X-ray flares

To better understand long-term flare activity, we present a statistical study on soft X-ray flares from May 1976 to May 2008. It is found that the smoothed monthly peak fluxes of C-class, M-class, and X-class flares have a very noticeable time lag of 13, 8, and 8 months in cycle 21 respectively with respect to the smoothed monthly sunspot numbers. There is no time lag between the sunspot numbers and M-class flares in cycle 22. However, there is a one-month time lag for C-class flares and a one-month time lead for X-class flares with regard to sunspot numbers in cycle 22. For cycle 23, the smoothed monthly peak fluxes of C-class, M-class, and X-class flares have a very noticeable time lag of one month, 5 months, and 21 months respectively with respect to sunspot numbers. If we take the three types of flares together, the smoothed monthly peak fluxes of soft X-ray flares have a time lag of 9 months in cycle 21, no time lag in cycle 22 and a characteristic time lag of 5 months in cycle 23 with respect to the smoothed monthly sunspot numbers. Furthermore, the correlation coefficients of the smoothed monthly peak fluxes of M-class and X-class flares and the smoothed monthly sunspot numbers are higher in cycle 22 than those in cycles 21 and 23. The correlation coefficients between the three kinds of soft X-ray flares in cycle 22 are higher than those in cycles 21 and 23. These findings may be instructive in predicting C-class, M-class, and X-class flares regarding sunspot numbers in the next cycle and the physical processes of energy storage and dissipation in the corona.     

Phase Relationship Between Sunspot Number, Flare Index and Solar Radio Flux

To understand better the variation of solar activity indicators originated at different layers of the solar atmosphere with respect to sunspot cycles, we carried out a study of phase relationship between sunspot number, flare index and solar radio flux at 2800 MHz from January 1966 to May 2008 by using cross-correlation analysis. The main results are as follows: (1) The flare index and sunspot number have synchronous phase for cycles 21 and 22 in the northern hemisphere and for cycle 20 in the southern hemisphere. (2) The flare index has a noticeable time lead with respect to sunspot number for cycles 20 and 23 in the northern hemisphere and for cycles 22 and 23 in the southern hemisphere. (3) For the entire Sun, the flare index has a noticeable time lead for cycles 20 and 23, a time lag for cycle 21, and no time lag or time lead for cycle 22 with respect to sunspot number. (4) The solar radio flux has a time lag for cycles 22 and 23 and no time lag or time lead for cycles 20 and 21 with respect to sunspot number. (5) For the four cycles, the sunspot number and flare index in the northern hemisphere are all leading to the ones in the southern hemisphere. These results may be instructive to the physical processes of flare energy storage and dissipation.