Hydrogen collisions in planetary atmospheres, ionospheres, and magnetospheres     

David L. Huestis 《Planetary and Space Science》2008,56(13):1733-1743

Hydrogen is the most abundant element in the universe. Molecular hydrogen is the dominant chemical species in the atmospheres of the giant planets. Because of their low masses, neutral and ionized hydrogen atoms are the dominant species in the high atmospheres of many planets. Finally, protons are the principal heavy component of the solar wind.Here we present a critical evaluation of the current state of understanding of the chemical reaction rates and collision cross sections for several important hydrogen collision processes in planetary atmospheres, ionospheres, and magnetospheres. Accurate ab initio quantum theory will play an important role. The collision processes are grouped as follows:

(a)

H⁺+H charge transfer,

(b)

H⁺+H₂(v) charge transfer and vibrational relaxation, and

(c)

H₂(v,J)+H₂ vibrational, rotational, and ortho-para relaxation.

In each case we provide explicit representations as tabulations or compact formulas. Particularly important conclusions are that H⁺+H₂(v) collisions are more likely to result in vibrational relaxation than charge transfer and H₂ ortho-para conversion is at least an order-of-magnitude faster than previously assumed.  相似文献   

典型表层岩溶泉域植被对降雨的再分配研究   总被引：1，自引：1，他引：0  

邓艳  蒋忠诚  徐烨  岳祥飞  李旭尧  梁锦桃 《中国岩溶》2018,37(5):714-721

本文在表层岩溶泉域植被结构特征分析的基础上,监测桂林丫吉试验场S31号泉域内香椿和云实两种主要植被的穿透雨和树干径流特征以及钻孔和表层岩溶水的变化。结果表明:香椿林的总穿透雨量1 861.83 mm,占总降雨总量的59.65%;云实灌丛总的穿透雨量为1 626.42 mm,占总降雨量的52.11%;穿透雨率随降雨量增加而减少。香椿林的树干径流总量为89.4 mm,占总降雨量的2.86%;云实灌丛的树干径流总量为27.79 mm,占总降雨量的0.89%;香椿林和云实灌丛的林冠截留总量分别为1 169.97 mm和1 466.99 mm,平均截留率为37.48%和47.01%;用水量平衡法计算得出以灌丛覆盖为主的S31号表层岩溶泉域年蒸散量为1 623.81 mm,占降水量的52.03 %,年径流深度为1 497.39 mm,占降水量的47.97%。植被冠层改变了降雨对表层岩溶带的补给形式和补给量。降雨经过植被冠层的截留后转化成穿透雨和树干径流进入表层岩溶带,穿透雨以连续波状的形式补给表层岩溶带,而树干径流则以快速集中的方式补给表层岩溶带。   相似文献   

2000~2010年南京都市区人口空间变动特征研究   总被引：4，自引：3，他引：1  

曾文  张小林  向梨丽  王亚华 《地理科学》2016,36(1):81-89

利用南京市第五次、第六次人口普查数据研究南京都市区2000~2010年人口空间变动及其规律。研究发现,① 10 a间南京都市区各地域人口均呈现增长态势,近郊区成为人口增长最为剧烈的区域;人口重心逐渐向南移动,同时人口分布的核心区域有向内收敛的趋势。② 根据测定系数、F检验与图像分析的综合判断,对数正态模型能够较好拟合人口分布的单核心结构,两年份曲线的变化表明郊区化的主体仍然是近郊区,尚未发展到远郊化的程度。多核心模型的拟合表明南京都市区已初步形成多核心结构,且主中心对人口仍具有强大吸引力;而多核心与单核心模型同时具有良好的拟合效果说明多核心结构尚未发育成熟。③ 南京都市区人口分布的空间异质性越来越高,人口分布趋于复杂,表明都市区正在向更加高级的阶段发展。  相似文献   

青藏高原雷暴的闪电特征及其成因探讨   总被引：2，自引：10，他引：2  

张廷龙  郄秀书  言穆弘 《高原气象》2007,26(4):774-782

通过对2003—2004年夏季青藏高原那曲地区30次雷暴过程的地面电场及闪电电场变化的分析,发现高原雷暴具有三极性电荷结构特征,其中73%(22次)的雷暴过程在其成熟阶段地面电场呈正极性,表明在雷暴云下部存在较常规雷暴范围广、电荷量大的正电荷区(LPCC),其余27%(8次)的雷暴同样具有三极性电荷结构特征,但LPCC相对要小得多。高原雷暴平均闪电频数一般只有1 fl.min-1,相对其它地区要小几十倍。对雷暴云闪电特征的进一步分析发现,具有较大LPCC的雷暴按照闪电特征可分为以云闪(IC)、负地闪(-CG)和正地闪( CG)为主的三类雷暴。结合气象参量分析发现IC型雷暴对应较高的地气温差和地表温度,相对湿度较小,而 CG型雷暴发生在傍晚,因此对应的地气温差偏小。  相似文献   

Catastrophic Rupture Induced Damage Coalescence in Heterogeneous Brittle Media     

Feng Rong  Haiying Wang  Mengfen Xia  Fujiu Ke  Yilong Bai 《Pure and Applied Geophysics》2006,163(9):1847-1865

In heterogeneous brittle media, the evolution of damage is strongly influenced by the multiscale coupling effect. To better understand this effect, we perform a detailed investigation of the damage evolution, with particular attention focused on the catastrophe transition. We use an adaptive multiscale finite-element model (MFEM) to simulate the damage evolution and the catastrophic failure of heterogeneous brittle media. Both plane stress and plane strain cases are investigated for a heterogeneous medium whose initial shear strength follows the Weibull distribution. Damage is induced through the application of the Coulomb failure criterion to each element, and the element mesh is refined where the failure criterion is met. We found that as damage accumulates, there is a stronger and stronger nonlinear increase in stress and the stress redistribution distance. The coupling of the dynamic stress redistribution and the heterogeneity at different scales result in an inverse cascade of damage cluster size, which represents rapid coalescence of damage at the catastrophe transition.  相似文献   

柑桔园林下穿透雨的分布特征   总被引：4，自引：0，他引：4       下载免费PDF全文

曹云  黄志刚  郑华  欧阳志云 《水科学进展》2007,18(6):853-857

研究了柑桔林下穿透雨的分布特征,结果表明:在测定期间,穿透雨量占总降雨量的68.3%,5月的穿透雨量最大(245.1 mm),而穿透雨率最大值(73.3%)出现在8月。穿透雨量与降雨量具有显著相关性(p<0.01),而穿透雨率与降雨量和降雨强度的相关性均达到显著水平(p<0.05)。柑桔林下穿透雨显示出明显的空间变化,各观测点间穿透雨率具有显著性的差异,而且穿透雨的空间异质性(穿透雨率的变异系数CV)随着降雨量或降雨强度的增加而降低,聚类分析也显示出穿透雨在不同观测点间具有差异性。柑桔林下穿透雨呈现明显的聚集效应。  相似文献   

云闪放电对云内电荷和电位分布影响的数值模拟   总被引：12，自引：3，他引：12       下载免费PDF全文

谭涌波  陶善昌  祝宝友  马明  吕伟涛 《地球物理学报》2007,50(4):1053-1065

我们应用改进的随机闪电参数化方案，对两次雷暴的起、放电过程进行了二维125 m和250 m分辨率云闪模拟试验，分析表明高分辨率模拟的云闪通道几何结构、延伸范围和最大垂直电场变化等特征与观测结果更为一致，并且揭示了云闪放电重新配置云内电荷分布和空间电荷中和过程的一种新的物理图像：(1) 云闪的直接物理效应是在已有的空间电荷区内沿着放电通道沉积异极性电荷、形成复杂的空间电荷分布，有效地导致云中电位和场强绝对值及静电场能量剧烈下降，使放电终止.其中：放电后在闪电通道经过主要区域，电位降到±30 MV之间，垂直电场强度也降到±20 kV·m-1之间，一次正或负云闪估计消耗掉107～1010 J静电能；(2) 云中电荷中和不是正、负空间电荷简单地直接相互抵消的瞬态过程，而是广泛分布的云中空间电荷与通道沉积的异极性电荷通过湍流交换、平流输送、重力沉降以及起电等多种因素逐渐混合并部分被中和的一个后续慢过程，其弛豫时间典型值在14～44 s之间，在此期间通道感应电荷总量下降到50%以下.并残余部分电荷参与后续放电前高空间电荷密度和强电场的重建过程.  相似文献   

Impact of river run-off on global ocean mass redistribution   总被引：1，自引：0，他引：1  

Henryk Dobslaw  Maik Thomas 《Geophysical Journal International》2007,168(2):527-532

  相似文献   

A scaled charge weight superposition model for rapid vibration estimation     

A. T. Spathis 《Fragblast: International Journal for Blasting and Fragmentation》2006,10(1):9-31

Rapid vibration estimation usually relies on charge weight scaling laws. These empirical curves that fit field data are sometimes involved in linear superposition models. A scaled charge weight superposition model combines the traditional charge weight scaling law within a linear superposition framework so that the influence of timing and blast design parameters may be assessed. The model involves an extra parameter of time overlap and poses a partial explanation for the over-estimation of blast vibration levels sometimes predicted by linear superposition models. It is suggested that the time overlap parameter be determined from measured vibration data. The new model recovers the Holmberg-Persson equation for near-field vibration from a single blast hole. Three examples compare the predictions of the new model with those from a linear superposition model. The results indicate a consistent, but not compelling demonstration of the predictive power of the scaled charge weight superposition model. Further verification studies are recommended using a wide range of blast types and scaled distances to points of interest. The new model lies between a traditional charge weight scaling law and a linear superposition model. It ignores waveform superposition explicitly but assumes non-linear interaction between adjacent charges in a blast within a user-defined time window. In that sense, the scaled charge weight superposition model offers an alternative method for rapid vibration estimation.  相似文献   

雷暴非感应起电机制的模拟研究：Ⅰ.云内因子影响   总被引：14，自引：13，他引：14  

言穆弘  刘欣生 《高原气象》1996,15(4):425-437

利用一个二维时变积云动力－电数值模式模拟了非感应起电过程，讨论了流场。降水以及冰晶谱分布对起电的影响。结果指出：只有在强上升气流穿过－２０℃高度层时才会产生强起电，且发生达到最大上升速度后出现降落的时段。  相似文献