贵州夏季暴雨的气候特征   总被引：3，自引：0，他引：3  

张艳梅  江志红  王冀  刘毅 《气候变化研究进展》2008,4(3):182-186

 利用贵州52个测站的1961-2006年历年夏季（6-8月）逐日降水资料,分析了贵州夏季暴雨的时空分布特征、周期振荡及其突变特征。结果表明：46 a来贵州夏季暴雨量呈增加趋势,并存在明显的年际、年代际变化特征;暴雨日数和暴雨量在1985年发生突变;暴雨日数和暴雨量均存在15 a和准10 a的周期振荡;暴雨日数和暴雨量EOF分解的第一特征向量的荷载场空间分布基本一致,表明全省呈偏多（少）的一致型同位相分布。  相似文献   

针对IPCC评估报告中海洋碳循环的疑问——δ¹³C收支平衡法的验证   总被引：2，自引：0，他引：2  

姜爱军  陈中笑  任慧军  程军  加藤喜久雄  大森保 《气候变化研究进展》2008,4(6):369-375

 通过对比IPCC历次评估报告中全球碳循环的收支发现,尽管评估报告在估算各主要碳库及其间的通量时差别不大,但表层至中深层海水间溶解无机碳通量却存在巨大差异。利用δ¹³C的收支平衡检验了这一通量的适用范围,结果表明：IPCC 1996年和2007年评估报告对此通量估计过大,而1990年和2001年评估报告估计偏小。  相似文献   

三维变分系统在我国夏季降雨预测中的应用试验     

孙建华  齐琳琳  朱江  赵思雄 《气候与环境研究》2007,12(3):413-425

采用MM5模式及其三维变分系统(MM5/3DVAR)对我国夏季降雨进行了一个月的连续预测试验,并对试验结果进行评估.试验中首先采用"National Meteorological Center(NMC)"方法,将2005年8月的MM5模式的预测结果形成与试验区域和水平分辨率相匹配的背景误差场,并将其与全球背景误差场进行了对比分析,结果表明,采用2005年8月MM5模式预报结果生成的背景误差场的基本特征与系统提供的全球背景误差场相似,且长度尺度随着水平分辨率的提高而减小.之后,分别利用NCEP再分析资料(NCEP试验)、NCEP再分析资料基础上采用CRESSMAN方法分析观测资料(LITT试验)和NCEP再分析资料基础上采用3DVAR系统同化观测资料(3DVAR试验)形成模式预报初始场,再次对2005年8月降雨进行逐日连续预报.逐日降雨预报结果表明,相对NCEP试验,LITT试验中1 和10 mm的预报评分有明显提高,但 25 和 50 mm的预报评分却有所下降,而3DVAR试验的预报评分在10 mm以上均有明显提高.对于降雨期间的形势场预报,3个试验中,除温度场和湿度场外,其他变量场的均方根误差随高度增加而增加,但相比而言,3DVAR试验的均方根误差小于其他2个试验.3DVAR试验对降雨的明显改进,可能是因为其对与背景场信息差别比较大的反应中尺度系统的观测资料的分析结果比较靠近观测资料.  相似文献   

The bulk kinetic power of radio jets in active galactic nuclei     

Minfeng Gu  Xinwu Cao  D. R. Jiang 《Monthly notices of the Royal Astronomical Society》2009,396(2):984-996

Based on the Königl's inhomogeneous jet model, we estimate the jet parameters, such as bulk Lorentz factor Γ, viewing angle θ and electron number density n _e from radio very long-baseline interferometry and X-ray data for a sample of active galactic nuclei (AGNs) assuming that the X-rays are from the jet rather than the intracluster gas. The bulk kinetic power of jets is then calculated using the derived jet parameters. We find a strong correlation between the total luminosity of broad emission lines and the bulk kinetic power of the jets. This result supports the scenario that the accretion process is tightly linked with the radio jets, though how the disc and jet are coupled is not revealed by present correlation analysis. Moreover, we find a significant correlation between the bulk kinetic power and radio extended luminosity. This implies that the emission from the radio lobes is closely related with the energy flux transported through jets from the central part of AGNs.  相似文献   

Old stellar population synthesis： new age and mass estimates for Mayall Ⅱ = G1     

Jun Ma  ;Richard de Grijs  ;Zhou Fan  ;Soo-Chang Rey  ;Zhen-Yu Wu  ;Xu Zhou  ;Jiang-Hua Wu  ;Zhao-Ji Jiang  ;Jian-Sheng Chen  ;Kyungsook Lee  ;Sangmo Tony Sohn 《天体物理学报》2009,(6):641-652

Mayall Ⅱ = G1 is one of the most luminous globular clusters （GCs） in M31. Here, we determine its age and mass by comparing multicolor photometry with theoretical stellar population synthesis models. Based on far- and near-ultraviolet GALEX photometry, broad-band UBVRI, and infrared JHKs 2MASS data, we construct the most extensive spectral energy distribution of G 1 to date, spanning the wavelength range from 1538 to 20 000A. A quantitative comparison with a variety of simple stellar population （SSP） models yields a mean age which is consistent with G1 being among the oldest building blocks of M31 and having formed within ～1.7 Gyr after the Big Bang. Irrespective of the SSP model or stellar initial mass function adopted, the resulting mass estimates （of order 10^7M⊙） indicate that GI is one of the most massive GCs in the Local Group. However, we speculate that the cluster＇s exceptionally high mass suggests that it may not be a genuine GC. Our results also suggest that G1 may contain, on average, （1.65±0.63） × 10^2L⊙ far-ultraviolet-bright, hot, extreme horizontal-branch stars, depending on the adopted SSP model. In addition, we demonstrate that extensive multi-passband photometry coupled with SSP analysis enables one to obtain age estimates for old SSPs that have similar accuracies as those from integrated spectroscopy or resolved stellar photometry, provided that some of the free parameters can be constrained independently.  相似文献   

Dynamical modelling of the elliptical galaxy NGC 2974     

Zhenglu Jiang 《Celestial Mechanics and Dynamical Astronomy》2009,103(1):31-47

In this paper we analyse the relations between a previously described oblate Jaffe model for an ellipsoidal galaxy and the observed quantities for NGC 2974, and obtain the length and velocity scales for a relevant elliptical galaxy model. We then derive the finite total mass of the model from these scales, and finally find a good fit of an isotropic oblate Jaffe model by using the Gauss-Hermite fit parameters and the observed ellipticity of the galaxy NGC 2974. The model is also used to predict the total luminous mass of NGC 2974, assuming that the influence of dark matter in this galaxy on the image, ellipticity and Gauss-Hermite fit parameters of this galaxy is negligible within the central region, of radius 0.5R _e.  相似文献   

Studying the Fermi GeV light curve of Vela with the two-pole caustic model     

Huan Yu  Jun Fang  Ze-Jun Jiang 《中国天文和天体物理学报》2009,9(12)

  相似文献   

Pb-Pb dating of black shales from the Lower Cambrian and Neoproterozoic strata, South China   总被引：2，自引：0，他引：2  

Yong-Quan Chen  Shao-Yong Jiang  Hong-Fei Ling 《Chemie der Erde / Geochemistry》2009,69(2):183-190

Black shales occur widely in the Lower Cambrian and Neoproterozoic strata on the Yangtze Platform, South China. In this study, Lower Cambrian black shales from Xiuning section and Late Neoproterozoic black shales from Weng’an section were studied and Pb isotopic compositions were analyzed following a stepwise acid-leaching technique. The ²⁰⁶Pb/²⁰⁴Pb ratios in both sections show large variations, from 18.906 to 43.737 in the Weng’an section and from 24.811 to 38.110 in the Xiuning section. In contrast, the ranges for ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb values in both sections are relatively smaller from 15.649 to 17.126 and 37.744-38.199 in the Weng’an section, and from 16.034 to 16.783 and 38.602-39.391 in the Xiuning section, respectively. These data yielded two Pb isotope isochron ages of 536±39 and 572±36 Ma, respectively. These ages well accord with other published data and we suggest that they represent the depositional ages for the Lower Cambrian Hetang Formation and the upper Neoproterozoic Doushantuo Formation in South China.  相似文献   

基于Oracle数据库的专题地理数据模型     

孟庆君  刘健  王飞  吴江 《测绘科学技术学报》2005,22(2):151-153

对Oracle Spatial组件中空间数据存储结构及对象关系数据模型进行了分析,然后结合专题地理数据库课题,提出了一种运用Oracle数据库的组件Oracle Spatial来管理专题地理数据的数据模型.并对这种数据模型的完整性和正确性进行了分析验证,取得了良好的效果.  相似文献   

GPS测量数据与计算机实时通信的研究与实现     

包欢  付子傲  朱江  王玉峰 《测绘科学技术学报》2005,22(3):219-221

介绍了GPS接收机与计算机之间实时通信的NMEA-0183数据格式,并以Leica 500系列接收机为例,介绍了如何进行GPS接收机的配置.在VC 平台下,给出了3种实现方式,并讨论了每种方式的优缺点,并指出了编程时的注意事项,对于开发类似的实时通信及监测系统具有一定的借鉴作用.  相似文献