我国部份地区雷暴活动、大气电场等与太阳活动的关系

本文用时序迭加法统计分析了1976—1985年太阳黑子一个完整周期内太阳活动与雷暴活动及地面大气电场之间的可能相关性。结果表明:高纬度地区有较好的相关性,耀斑爆发以后雷暴指数有明显增大趋势,最大关联日在+5日以后。中、低纬度地区几乎不存在相关性。随着耀斑强度增强,相关性也增大,且影响区域从高纬度向中、低纬度移动。在耀斑爆发后2天左右,地面电场强度增大,其关联日比雷暴指数提前。太阳黑子数和雷暴活动之间的相关性很微弱。本文又从全球电路概念出发,简单地解释了形成上述相关性的可能原因。     

A FUMIGATION DIFFUSION MODEL DURING THE MOUNTAIN-VALLEY WIND SHIFT PERIOD

The fumigation during the mountain-valley wind shift has been first identified as a special type of pol-lutant diffusion using the monitoring measurements of Dukou,Southwest Sichuan,China.Such a pheno-menon occurs frequently all year around but summer,particularly in winter months.A new model for thefumigation during the mountain-valley wind shift period is developed that allows satisfactory explanation ofthe fact.Analyses indicate that the model can more accurately predict not only the high concentration ofPollutants but the time and locality of the occurrence as well.The ground concentration of SO_2 during fumigation is several times up to over a decade higher thanthe daily mean for the whole region,one of the main contamination processes that affect the air quality ofthe city.The medel analyses provide a basis for more effective prediction of the quality and precautionstudy against the disaster.     

Production of N2O,CH4, and CO2 from soils in the tropical savanna during the dry season

Emissions of N₂O, CH₄, and CO₂ from soils at two sites in the tropical savanna of central Venezuela were determined during the dry season in February 1987. Measured arithmetic mean fluxes of N₂O, CH₄, and CO₂ from undisturbed soil plots to the atmosphere were 2.5×10⁹, 4.3×10¹⁰, and 3.0×10¹³ molecules cm^-2 s^-1, respectively. These fluxes were not significantly affected by burning the grass layer. Emissions of N₂O increased fourfold after simulated rainfall, suggesting that production of N₂O in savanna soils during the rainy season may be an important source for atmospheric N₂O. The CH₄ flux measurements indicate that these savanna soils were not a sink, but a small source, for atmospheric methane. Fluxes of CO₂ from savanna soils increased ninefold two hours after simulated rainfall, and remained three times higher than normal after 16 hours. More research is needed to clarify the significance of savannas in the global cycles of N₂O, CH₄, CO₂, and other trace gases, especially during the rainy season.     

IMAGE PREDICTION FOR TORRENTIAL RAIN AREAS

A new method is presented for the prediction of a torrential rain (TR) area, where some atmo-physical parameters are used with their given values as criteria most favorable for the occurrence ofTR; an over-all examination is done of the relative favorabilities of these factors for the TR productionin other regions which are then composited and numeralized by means of the theory of nonlinearmapping with the results plotted (‘reflected') on a weather chart, allowing to make an objectiveforecast of the TR area. The preliminary results indicate that the technique is able to objectivelycomposite and clearly exhibit principal distribution features of the parameters on the map, thus show-ing a certain amount of effectiveness for the diagnosis and prediction of a TR area. Regression analysis is used for factor selection to automatically discriminate and locate the jet-stream axis with the aid of a computer. In the calculation of the mapping the gradient method isadopted, in the light of the functional properties of the optimized index K, in place of the simplerelaxational iteration now in general use, thus getting rid of the non-convergence by the iterationmethod because of the increased number of the samples used. The square of the gradient mod-ulus <10~(-4) is set to be the criterion for the iteration convergence. The improved method canmeet the requirements of operational forecasts generally with 50 or less iterations.     

THE NUMERICAL MODELING OF RADIATION FOG

The formation and development of radiation fog are studied by using a one-dimensional model.Theresults are as follows:(1)The fog can change the ambient wind and temperature fields,on the contrary,theambient fields may also influence the fog;(2)The modeling fog forms initially at a certain level above thesurface,which is detailedly explained in the paper;(3)Turbulence delays the formation of fog but promotesits development;(4)Whether fog liquid water content exchange coefficient equals momentum exchangecoefficient has no influence on the numerical results.In addition,wind,temperature,exchange coefficient,and net radiative flux before and after the formation of radiation fog,are also studied.     

THE RELATIONSHIP BETWEEN INDIAN MONSOON SYSTEMS IN SUMMER AND THE CONTINUOUS HEAVY RAIN OVER THE UPPER REACHES OF CHANGJIANG RIVER

In this paper,the continuous heavy rains over the upper reaches of Changjiang River during June—Augustare analyzed.They are closely related to the Indian monsoon systems.The average synoptic situationsand the average distributions of some meteorological elements over the Bay of Bengal during the period ofheavy rains are presented.The correlation coefficients between meteorological elements and rainfall arecalculated and the main monsoon influence systems and the key regions are denoted.Results can be usedas a reference in the 24 h forecast of rainfall.     

钻孔走向偏斜的初步探讨

在急倾斜构造部位大力使用硬合金回转钻进时,常常会产生弯曲度很大的走向偏斜情况。这是因为不同岩层的阻力差异使钻头受到一种平行于岩层走向的偏斜力,迫使钻头向侧方研磨井壁;在不同井径变换部位所产生的偏斜效果是不同的。这样造成钻孔沿地层走向发生有规律的定向偏斜。     

大别山北麓佛子岭群的特征及其形成的大地构造环境

佛子岭群主要由一套绿片岩相的变质岩组成,分布在安徽境内的大别山北麓。其上部为一套变质的复理石建造,下部为变质的火山-沉积岩建造。佛子岭群的变质火山岩的岩石化学特征及佛子岭群的岩石组合特征表明,佛子岭群是发育在一断陷盆地中,该断陷盆地可能在晚元古代早期开始拉张,在晚元古代末期闭合。在此期间,郯-庐断裂带在华北断块和大别山古老断块之间的拉张与闭合过程中可能起着类似于转换断层的作用。     

北京密云平顶山铬铁矿床深源成因机制的研究

密云平顶山含铬铁矿超镁铁岩体是残留上地幔岩进一步熔融的方辉橄榄岩岩浆两次沿深断裂侵入于前寒武系黑云斜长片麻岩层间成岩。对称结晶分异作用,使铬铁矿呈浸染状沿着岩体中心相早期形成的致密状矿石,对称聚合富集成矿。     

Intensity attenuation based on earthquake fault-rupture model

Based on the statistical outcomes relevant to elliptical isoseisms given in ref. [1], the average focal depth and rupture length of fault for earthquakes with different magnitudes or epicentral intensities occurring in East and West China are discussed. A set of intensity attenuation functions appropriated to point source (regarding focal distance as the distance parameter in the attenuation law) and the line source (regarding the shortest distance from the site to rupture line or the average distance from the site to both ends of the rupture line as the distance parameter) are proposed.