Physical mechanisms of man-made influences on the magnetosphere

Since the discovery of the Luxembourg effect in the 1930s, it is clear that man-made activities can perturb the ionosphere and the magnetosphere. The anthropogenic effects are mainly due to different kinds of waves coming from the Earth's surface. Acoustic-gravity waves are generated by large explosions, spacecraft launches, or flight of supersonic planes. Electromagnetic waves are active in different frequency ranges. Power line harmonic radiation which is radiated in the ELF range by electrical power systems can be observed over industrial areas. At VLF and HF, the ground-based transmitters used for communications or radio-navigation heat the ionosphere and change the natural parameters. A large variety of phenomena is observed: wave-particle interaction, precipitation of radiation belt electrons, parametric coupling of EM whistler waves, triggered emissions, frequency shift, and whistler spectrum broadening. This paper will review the different physical mechanisms which are relevant to such perturbations. The possibility of direct chemical pollution in the ionosphere due to gas releases is also discussed.     

Processing of oxidised nitrogen compounds by passage through winter-time orographic cloud

Four case studies are described, from a three-site field experiment in October/November 1991 using the Great Dun Fell flow-through reactor hill cap cloud in rural Northern England. Measurements of total odd-nitrogen nitrogen oxides (NO _y ) made on either side of the hill, before and after the air flowed through the cloud, showed that 10 to 50% of the NO _y , called NO _z , was neither NO nor NO₂. This NO _z failed to exhibit a diurnal variation and was often higher after passage through cloud than before. No evidence of conversion of NO _z to NO₃ ^- in cloud was found. A simple box model of gas-phase chemistry in air before it reached the cloud, including scavenging of NO₃ and N₂O₅ by aerosol of surface area proportional to the NO₂ mixing ratio, shows that NO₃ and N₂O₅ may build up in the boundary layer by night only if stable stratification insulates the air from emissions of NO. This may explain the lack of evidence for N₂O₅ forming NO₃ ^- in cloud under well-mixed conditions in 1991, in contrast with observations under stably stratified conditions during previous experiments when evidence of N₂O₅ was found. Inside the cloud, some variations in the calculated total atmospheric loading of HNO₂ and the cloud liquid water content were related to each other. Also, indications of conversion of NO _x to NO _z were found. To explain these observations, scavenging of NO _x and HNO₂ by cloud droplets and/or aqueous-phase oxidation of NO₂ ^- by nitrate radicals are considered. When cloud acidity was being produced by aqueous-phase oxidation of NO _x or SO₂, NO₃ ^- which had entered the cloud as aerosol particles was liberated as HNO₃ vapour. When no aqueous-phase production of acidity was occurring, the reverse, conversion of scavenged HNO₃ to particulate NO₃ ^-, was observed.     

Natural and anthropogenic C2 to C6 hydrocarbons in the central-eastern Venezuelan atmosphere during the rainy season

The levels of low molecular weight hydrocarbons were measured at pristine sites and rural locations affected by hydrocarbon emissions from oil and gas producing fields in Venezuela. At the clean sites, lower concentrations of C₂ to C₆ alkanes were observed, whereas, in comparison with remotes sites, very much higher levels were measured at the polluted sites. Alkenes present relatively high concentrations, with isoprene being the most abundant, all over the study region. The main sources of alkenes are likely to be natural, mainly from vegetation. The levels of alkanes recorded at the clean sites and the alkene levels found everywhere in the region are in agreement with the values reported for other clean sites in the tropics. The increase of ozone production capacity due to the anthropogenic emissions of alkanes from oil and gas fields was estimated. Due to the presence in the atmosphere of important amounts of naturally emitted isoprene, ethene and propene, which makes a substantial contribution to the reactivity of the hydrocarbon mixture, a small increase (<5%) was estimated to occur in the capacity of the ozone production at a regional scale during the rainy season.     

Collection and analysis of atmospheric ozone samples

Anomalies found in the isotope ratios of ozone are traceable to the ozone formation process. Metastable electronic states may be responsible for the preferred production of the heavy molecules. While laboratory isotope data and first tropospheric results agree well in the magnitude of isotope enrichments, stratospheric measurements show often higher values. Only through the collection of ozone samples can sufficiently large amounts of gas be obtained to analyze the three isotopes ⁴⁸O₃, ⁴⁹O₃, and ⁵⁰O₃. Collector systems have been developed and successfully operated in the troposphere and in the stratosphere. They will play in the future an important role in atmospheric oxygen isotope studies.     

混合物电导率和介电常数的研究

应用电场理论研究混合物的电性，得出了混合物的电导率公式和介电常数公式．这一结果表明：混合物的电导率决定于混合物各成分电导率的均值和方差；混合物的介电常数决定于混合物各成分介电常数的均值和方差．作为所得结果的应用，给出了岩石的电导率公式和介电常数公式．     

STUDY ON CANONICAL AUTOREGRESSION PREDICTION OF METEOROLOGICAL ELEMENT FIELDS*

Through extension of canonical correlation to the analysis of meteorological element fields (MEF), a concept from combination of canonical autocorrelation with canonical autoregression (CAR) is developed for short-term climatic prediction of MEFs with a formulated scheme. Experimental results suggest that the scheme is of encouraging usefulness to a weak persistence MEF,i.e., rainfall field and, in particular, to a strong persistance one like a SST field.     

龙门山断裂带测区古构造残余应力随深度分布及带中残余能量

以岩体正交异性弹性理论为基础，用Ｘ射线法，在龙门山断裂带测区，选取３个小区深钻孔系列的岩心，测量了岩体中宏观残余应力场的水平和铅直三维主分量、水平和铅直最大剪应力，及其应变能密度随深度的分布，分析了它们沿深度的分布规律，估算了该断裂带岩体中储存的宏观残余弹性应变能的量级     

The MT inversion for conductivity anisotropy and EDA precursor，stress field and deformationbandintheEarthsdeepcrust

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地电短临前兆产生机理及一种新的短临预报方法（谐振预报法）

研究了地电短临震兆机理，在此基础上给出了引潮力触发地电短临前兆模式。据此从理论上分析了地电临震震兆特征，并以唐山７．８级大震为例，从实际观测中检出具有此模式特征的震兆（具有起潮力特征），从而验证了所提模式理论的客观存在的可能性。最后给出与此有关的地电短临预报方法。即，根据脆性岩石失稳的相对刚度比较准则，定义部分岩体刚度λ＝０的状态为临震阶段，分析λ＝０时起潮力引起位移的特征和规律，得出原地监测岩体刚度是否为零（进入临震阶段）的方法。因为在弹性阶段，λ为较大正值，微小的起潮力只引起微小的位移，此时的电响应甚小，通常检测不到；但随着构造力的积累，介质进入临震阶段，此时同样微小的起潮力却可引起甚大的位移（λ＝０时，位移为无穷大），从而产生可检测的电响应。由于这种电响应具有与起潮力相同的周期，故可把临震电响应同各种干扰区分开，判定为临震前兆，从而建立了地电临震前兆起潮力触发模式，并可给出相应的短临预报方法。对１９７６年唐山７．８级强震前后震中周围地电阻率及大地电场实测资料进行谱分析，发现仅在主震前二个月至半月内，两种不同物理本质的电响应分别出现与起潮力ＭＳ波与ＭＳｆ波周期相同的异常变化。这是对所提临震前兆模式和预报     

天水地震区深部地温场的有限元计算

用有限元方法计算了天水地震区上地壳地温场。结果表明，影响该区浅部（层）地温场的主要因素是基底构造和断裂构造。祁连褶皱系为高热异常区，秦岭褶皱系为低热异常区，西秦岭北缘断裂带为地温梯度带。认为该带历史地震的发生与热应力差有关