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In this paper results and analysis of geomagnetic observations during previous 5 solar eclipses occurred in China are summarized. They are solar eclipses: No. 1, on 19 June 1936 in Heilongjiang of NE China; No. 2, on 21 September 1941 in Fujian; No. 3, on 19 April 1958 in Hainandao; No. 4, on 22 September 1968 in Xinjiang; and No. 5, on 16 February 1980 in Yunnan of SW China. The authors took part in the last 2 expeditions and joint programmes in the track of totality.The methods of evaluation for eclipse effects on the geomagnetic field are briefly described both for the quiet and disturbed days. The discussion of these data is made with reference to Chapman's theoretical consideration on optical eclipse effect, together with the quiet-day overhead current systems in the upper atmosphere. We conclude that optical eclipse effects are easily observable under favourable conditions, and further observations are essential to establish the yet unknown effects due to corpuscular eclipses. 相似文献
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With the aid of the Akasofu's energy coupling function between the solar wind and the magnetosphere, we have made in this paper an analysis of about 20 geomagnetic storms recorded at Beijing during the period of years 1966 to 1972. There is a close correlation between the energy coupling function ? and the geomagnetic indices ap and Kp. All in all an empirical formula as ? ～ 1?2 × 1017ap has been found for the geomagnetic storms occurred in a low latitude station, i.e. Beijing of China. Comparisons of the horizontal component Hmax (in γ) and ?(1018 erg s?1) in Table 1 indicate that the development of storm main phase at Beijing depends very much on the ? values thus involved. Also, these are well illustrated for several individual storms as mentioned in the second section of the paper. In concluding this paper some brief discussions are made and included. It is hoped that geomagnetic observations in the middle and low latitudes from our vast country should make further contributions to the study of solar wind-magnetosphere coupling, including the Akasofu's energy coupling function. 相似文献
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Dugin Kaown Eun-Hee Koh Bernhard Mayer Heejung Kim Dong Kyu Park Byeong-Hak Park Kang-Kun Lee 《Hydrogeology Journal》2018,26(6):2009-2020
The extent of denitrification in a small agricultural area near a river in Yangpyeong, South Korea, was determined using multiple isotopes, groundwater age, and physicochemical data for groundwater. The shallow groundwater at one monitoring site had high concentrations of NO3-N (74–83 mg L?1). The δ15N-NO3 values for groundwater in the study area ranged between +9.1 and +24.6‰ in June 2014 and +12.2 to +21.6‰ in October 2014. High δ15N-NO3 values (+10.7 to +12.5‰) in both sampling periods indicated that the high concentrations of nitrate in the groundwater originated from application of organic fertilizers and manure. In the northern part of the study area, some groundwater samples showed elevated δ15N-NO3 and δ18O-NO3 values, which suggest that nitrate was removed from the groundwater via denitrification, with N isotope enrichment factors ranging between ?4.8 and ?7.9‰ and O isotope enrichment factors varying between ?3.8 and ?4.9‰. Similar δD and δ18O values of the surface water and groundwater in the south appear to indicate that groundwater in that area was affected by surface-water infiltration. The mean residence times (MRTs) of groundwater showed younger ages in the south (10–20 years) than in the north (20–30 years). Hence, it was concluded that denitrification processes under anaerobic conditions with longer groundwater MRT in the northern part of the study area removed considerable amounts of nitrate. This study demonstrates that multi-isotope data combined with physicochemical data and age-dating information can be effectively applied to characterize nitrate contaminant sources and attenuation processes. 相似文献
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Nak-Youl Ko Kang-Kun Lee 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):649-660
We examine the effect of uncertainty due to limited information on the remediation design of a contaminated aquifer using
the pump and treat method. The hydraulic conductivity and contaminant concentration distributions for a fictitious contaminated
aquifer are generated assuming a limited number of sampling locations. Stochastic optimization with multiple realizations
is used to account for aquifer uncertainty. The optimization process involves a genetic algorithm (GA). As the number of realizations
increases, a greater extraction rate and more wells are needed. There was a total cost increase, but the optimal remediation
designs became more reliable. Stochastic optimization analysis also determines the locations for extraction wells, the variation
in extraction rates as a function of the change of well locations, and the reliability of the optimal designs. The number
of realizations (stack number) that caused the design factors to converge could be determined. Effective stochastic optimization
may be achieved by reducing computational resources. An increase in the variability of the conductivity distribution requires
more extraction wells. Information about potential extraction wells can be used to prevent failure of the remediation task. 相似文献
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本文扼要介绍中美科学合作夜空气辉观测研究的成果.首先,气辉合作研制成一套四通道的气辉观测仪器,其次,在北京近郊怀柔和兴隆二台站进行观测.从1986年至1989年积累114日成功地提供我国第一批气辉观测数据.本文着重分析其中41次对绿线5577和红线6300的时间变化,进行频谱分析,探讨气辉与大气扰动(声重波)和气辉与大磁暴之间的关系.最后文末提些今后开展气辉研究意见. 相似文献
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It is generally understood that groundwater flow is greatly affected by linear features associated with geologic structures such as fractures, faults, lithologic boundaries, and fold axes. In crystalline rock aquifers, such geologic structures seem to be closely related to large-scale groundwater flow field and well productivity. However, quantification of how the structures are related with the flow and well productivity is not so simple, because it involves many factors of hydraulic properties and flow phenomena. This study proposes a semianalytical method to analyze the effects of highly permeable geologic discontinuities on the groundwater flow system. Effects of geological discontinuities on groundwater productivity are interpreted from the geometry of linear geologic features by the conformal mapping of the spatial distribution function. The proposed method is compared with the numerical methods, and the applicability and usefulness of the method to delineate high well yield areas from a limited number of well productivity measurements is discussed. 相似文献
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发生于2003年10～11月许许多多日地关系重大事件,西方称为万圣节日地事件或风暴(Halloween Events 或Halloween Storms),并予以特别关注.本文综述对这次日地重大事件的国际集会讨论和公开出版的文献,在太阳爆发方面包括：（1）太阳活动区与耀斑;（2）日冕物质抛射CMEs;（3）日冕激波;（4）太阳高能粒子SFPs;（5）活动区能量与面积、耀斑大小和CME速率.在日球层与地球物理效应方面,包括：（1）日球层响应;（2）大磁暴与宇宙线磁层效应;（3）热层与电离层效应;（4）白天极光、臭氧亏损;（5）中国学者工作.期望我国在此基础上积极开展工作和取得创新. 相似文献