Behaviour of H2O2, NH3, and black carbon in mixed-phase clouds during CIME

We investigated the partitioning of trace substances during the phase transition from supercooled to mixed-phase cloud induced by artificial seeding. Simultaneous determination of the concentrations of H₂O₂, NH₃ and black carbon (BC) in both condensed and interstitial phases with high time resolution showed that the three species undergo different behaviour in the presence of a mixture of ice crystals and supercooled droplets. Both H₂O₂ and NH₃ are efficiently scavenged by growing ice crystals, whereas BC stayed predominantly in the interstitial phase. In addition, the scavenging of H₂O₂ is driven by co-condensation with water vapour onto ice crystals while NH₃ uptake into the ice phase is more efficient than co-condensation alone. The high solubility of NH₄⁺ in the ice could explain this result. Finally, it appears that the H₂O₂–SO₂ reaction is very slow in the ice phase with respect to the liquid phase. Our results are directly applicable for clouds undergoing limited riming.     

磁通门磁变仪与经典磁变仪状态函数之比较

分析了影响磁通门磁变仪定向状态函数和经典磁变仪定向状态函数改变的因素，对磁通门磁变仪定向状态函数和经典磁变仪定向状态函数及其稳定性进行了比较，得出了有益的结论。     

1998年5月磁暴磁层电流体系的地磁效应分析

低纬度地区地磁场的短时变化主要由以下电流体系产生:电离层发电机电流(IDC)、对称环电流(SRC)以及由部分环电流和Ⅱ区场向电流及其电离层回路组成的内磁层三维电流体系(PRFI).此外,由Ⅰ区场向电流及其电离层回路组成的电流体系(FACI)所产生的低纬地磁场也是不可忽略的.本文针对1998年5月1-6日的大磁暴,首先利用多个同子午线台站对的数据分离并消去由IDC电流产生的Sq场.然后,通过线性建模分离其他电流体系产生的磁场成分.结果表明:(1)发生在5月1-6日的磁暴可以分为两个过程,PRFI和FACI电流体系在1-3日不明显,在4-5日伴随着亚暴强烈发生.(2)SRC的变化情况在第一阶段同Dst指数相似,在第二阶段明显滞后于Dst指数.(3)在5月4-5日,PRFI在SRC之前增强,随着PRFI和FACI的恢复,SRC开始增强.这一结果为我们了解环电流和场向电流的形成以及它们的关系提供线索.     

A note on magnetic modelling with remanence

The general problem of magnetic modelling involves accounting for the effect of both remanent magnetization and the application of an external magnetic field. However, as far as the disturbing field of a magnetic body in a magnetic environment is concerned, there is an equivalence between the effects of these two causations that allows the remanence to be represented in terms of an equivalent primary magnetic H field. Moreover, due to the linearity of the magnetic field in terms of its causations, the general modelling problem involving an applied magnetic field in the presence of remanence can be simply and more efficiently dealt with in terms of an equivalent primary field acting in the absence of any remanent magnetization.     

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.     

MRI对肺癌分析的价值

本文分析了30例肺癌的 MRI 及手术病理分期的结果。结果表明:MRI 能够比较准确地显示肿块的大小、范围、部位及叶以上支气管的受累情况;容易显示胸壁、纵隔、隔肌及远处转移,对胸壁受侵犯诊断准确率为86.7%;无需使用造影剂能直接显示肺门及纵隔区大血管的受累与否、诊断准确率为83.3%;对肺门及纵隔淋巴结转移诊断准确率为90%,敏感性为91.3%,特异性为85.7%;与手术病理分期结果比较,MRI 对肺癌分期准确率为80%。故认为 MRI 是对肺癌分期癌一种准确的无创性新方法。     

多剩磁成分的主成分法分离及其应用

岩石的多剩磁成分的分离是古地磁研究的重要环节之一.Kirschvink（1980）提出的主成分分析法（PCA）能有效地进行多剩磁成分的方向分离.作者认为,最大角偏差（MAD）值的选择应视各磁成分的剩磁谱组合特征而定,剩磁相似度的提出,可以帮助确定MAD值选取的最佳值.在主成分法分离的剩磁方向的基础上,作者提出了一种多剩磁成分的强度分离方法,籍此可以进一步研究各分离磁组分的剩磁谱特征及其成因,并将以上方法应用于新疆柯坪地区晚古生代地层的剩磁分离.     

S_q发电机电流的逐日变化和S_q指数

用中国地磁台站的资料,研究了S_q逐日变化的形态学特征,用理论模型计算了磁层环电流、部分环电流、场向电流、磁尾电流、Chapman-Ferraro电流的地磁效应.在消除了这些磁层电流体系的影响之后,得到了电离层潮汐风发电机电流产生的磁场S_q变化.对1973年的资料研究表明,S_q发电机电流的逐日变化主要表现在强度上,即使在磁扰期间,也可以分离出形态稳定的S_q变化.由此提出了一种新的地磁指数——S_q指数,用来描述S_q发电机电流强度的逐日变化.     

高精度磁测在勘查热液硼矿床中的应用

常宁县汤市硼矿属接触交代—热液型矿床。区内沉积岩和花岗岩磁性微弱或无磁性,与硼矿密切相关的矽卡岩及硼矿石中磁铁矿含量较高。大理岩型硼矿石磁化率168×10~(-1)nT,矽卡岩型硼矿石磁化率29033×10~(-1)nT。已知半边街矿段△T等值线形态反映出矿体产状,并与矿体投影形态一致。用△T高精度磁测寻找埋深大、磁性弱的隐伏内生硼矿是有效的方法之一。从已有磁测资料分析,预测该地区瓦盏洲一新屋山、周家屋场一带可作为硼矿找矿靶区。     

酒西盆地、酒东盆地第三系磁性地层的划分与对比

本文运用磁性地层学理论和方法对酒西盆地、酒东盆地第三系进行了划分对比,部分修正了前人的划分方案,在此基础上对两盆地第三纪各时期沉降速率进行了估算和比较,并对它们的构造运动特征提出了见解。