1995～1996年冬季高原地区雪灾气候分析

分析了１９９５－１９９６年冬季我国高原东部地区形成雪灾的降水和平均环流异常的关系，以及雪灾与高原地我冬季降水气候振动及其背景关系。结果表明，高原雪灾和冬季降水从６０、７０年代至８０、９０年代有增多的趋势。     

Climatic variations in the past 140 ka recorded in core RM, east Qinghai-Xizang Plateau

The sequences of climatic evolution are reconstructed by the analyses of δ¹³C and δ¹⁸O of carbonate from core RM in the Zoige Basin since 140 kaB. P. During the Last Glaciation there existed at least seven warm climatic fluctuations and five cold events correlated with the records of ice core and deep sea, and during the preceding last interglacial period there were two cold climatic variations coinciding with the record of ice core GRIP. These results de-pict climatic instability in east Qinghai-Xizang Plateau over the last interglacial period. In addition, the environmental proxies of the carbonate content and pigments indicate the similar results to the stable isotope record from core RM. Project supported by the Chinese Climbing Project (85-029-02-01).     

Microzonation of the city of Basel

During the past centuries, the city of Basel has suffered damage caused by earthquakes. One extraordinary event described in historical documents is the strong earthquake which occurred in 1356. The 1356 event, one of the strongest earthquakes in northwest-Europe, was obviously much stronger than the low-magnitude earthquakes observed in the area during this century. Even though the present seismicity in the Basel area is low, strong earthquakes have to be expected due to the city's geographical location close to the northern boundary of the African-European convergence zone, at the southern end of the Rhinegraben. A crucial step towards preparedness for future events and mitigation of earthquake risk involves a microzonation study of the city. The study is carried out in three steps: (1) a detailed mapping of the geology and geotechnical properties of the area, (2) measurement, interpretation and modelling of ambient noise data, and (3) numerical modelling of expected ground motions during earthquakes. A qualitative microzonation of the centre of Basel is presented, and it is discussed by comparing it to the historically reported damage of the 1356 earthquake.     

Analysis of geomagnetic variations in south-western Nigeria

Geomagnetic variations, observed at 11 sites in south-western Nigeria, have been analysed to derive interstation transfer functions with the site at Ile-Ife as reference station. The study involves frequencies from 1 to 6 c.p.h. The reference station Ile-Ife is 160 km northward of the continental slope off the Nigerian coastline and 400 km southward of the dip equator. The analysis has been carried out separately with selected data sections of a few hours length during daytime and during the night. Thus expressed linear relations between field components are in the case of day events of dual implication: (1) for the source field structure of the equatorial electrojet, (2) for internal conductivity conditions, including the coast effect from the Bight of Benin. Conductivity anomalies are the sole cause for an observed spatial variability of night events. A 2-D thin-sheet conductivity model has been derived taking both the source and the coast effect into consideration. This model provides a reasonably good fit between observed and computed transfer functions during day and night.     

High atmospheric NO x levels and multiple photochemical steady states

Previous zero-dimensional photochemical calculations indicate that multiple tropospheric steady states may exist, in which different NO _x (NO+NO₂) levels could be supported by the same source of NO _x . To investigate this possibility more closely, a one-dimensional photochemical model has been used to estimate the rate of removal of atmospheric NO _x compounds at different NO _x levels. At low NO _x levels NO _x is photochemically converted to HNO₃, which is removed by either wet or dry deposition. At high NO _x levels formation of HNO₃ is inhibited, and NO _x is removed by a variety of other processes, including rainout of N₂O₄ and N₂O₅, surface deposition of NO and NO₂, and direct dissolution of NO and NO₂ in rainwater. Multiple steady states are possible if surface deposition of NO _x is relatively inefficient. The NO _x source required to trigger high atmospheric NO _x levels is approximately 10 to 15 times the present global emission rate-less than half the source strength predicted by the zero-dimensional model. NO _x mixing ratios in excess of 10^-7 would cause severe damage to the ozone layer and could result in either a climatic warming or cooling, depending upon the amount of NO₂ present.     

Interannual and long-term variability of the summer monsoon and its possible link with northern hemispheric surface air temperature

Some statistical properties of the summer monsoon seasonal rainfall for India during the last 100 years (1881–1980) are presented. The most recent decade of 1971–1980 shows the lowest value of standard-decadal average monsoon rainfall (86.40 cm) and is also characterised by the second highest value of coefficient of variation in monsoon rainfall (12.4 %). The combined last two standard-decadal period of 1961–1980 was the period of the largest coefficient of variation and the lowest average monsoon rainfall for India. The possible influence of global climatic variability on the performance of the monsoon is also examined. Analyses of correlation coefficient show that a statistically significant positive relationship with a time-lag of about six months exists between monsoon rainfall and northern hemispheric surface air temperature. A cooler northern hemisphere during January/February leads to a poor monsoon. All the major drought years during the last 3 decades had much cooler January/February periods over the northern hemisphere—1972 having the coldest January/February with a temperature departure of −0.94°C and the most disastrous monsoon failure.     

Recognition of environmentally caused variations in radon time series

Four techniques (pattern recognition, Fourier transformation, cross-correlation, and multiple linear regression) have been used to recognize nontectonic environmental factors affecting groundwater radon data collected by the Caltech automated geochemical network. Several factors, including air temperature, rainfall, water level, carbon dioxide concentration in the water, and barometric pressure, were found to correlate with radon level at some stations in the network. For example, approximately 60% of the variance in radon signal at one site studied (Pacoima) could be accounted for by nontectonic influences. However, it was not possible to correlate all the observed changes in radon concentration with nontectonic environmental variables. Some of the observed radon anomalies did appear to be related to either regional changes in tectonic strain or some individual earthquakes. A model is developed to account for spike-like increases in radon caused by carbon dioxide emission.     

Acidity of twelve northern New England (U.S.A.) lakes in recent centuries

Studies of sediment cores from 12 acidic lakes in granitic, forested and uninhabited catchments in northern New England, U.S.A. produced diatom-inferred pH (IpH) 5.2 to 5.8 and alkalinity (Ialk) –12 to 31 µeq l^–1, with slowly declining values at some lakes, for one to four centuries prior to logging. Increases of IpH (0.05 to 0.60) and Ialk (5 to 40 µeq l^–1) correlate with logging in the catchments in the early-1800s to early-1900s. Recovery to pre-logging IpH and Ialk correlates with forest succession toward conifers, and is completed in the late-1800s to mid-1900s. Beginning at 1915–1920 (4 lakes), 1930–1950 (4 lakes) and 1965–1970 (4 lakes), IpH and Ialk start decreasing below pre-logging values due to atmospheric acidic deposition, leading to respective total decreases of 0.10 to 0.45 (X=0.25) and 5 to 25 µeq l^–1 (X=15). Inputs of anthropogenic Pb, Zn, V, polycyclic aromatic hydrocarbons, and soot from the atmosphere are first detectable in early- to late-1800s sediment, and Cu in late-1800s sediment, increase rapidly in the late-1800s to mid-1900s, and level off or decrease since the 1960s — partly due to emission controls. Decreasing Ca, Mn, and possibly Zn relative to other metals and normalized to organic content, and increasing flux of Fe to the lakes, indicate soil and water acidification after 1900.This is the fourteenth of a series of papers to be published by this journal which is a contribution of the Paleoecological Investigation of Recent Lake Acidification (PIRLA) project. Drs. D. F. Charles and D. R. Whitehead are guest editors for this series.     

Seismogeological and hydrological criteria for the New European Macroseismic Scale (MSK-92)

In 1988, an ESC Working Group Macroseismic Scales started upgrading the MSK-81 Intensity Scale. This paper presents the background and decisions made with respect to the so-called seismogeological effects. Discussion has pointed out that they cannot be treated and used in the same way as the effects on humans, objects and buildings, for many reasons. Therefore, the WG adopted the solution of using such effects as a side tool for intensity assessment, providing a comprehensive table where the experimental relations between seismogeological effects and intensity degrees - assessed by means of other effects - are presented.     

旧石器时代东亚、西亚之间的关系

通过实地考察和对收藏标本的细致研究,以获取第一手资料的方式,文章客观地评价了中国古人类学研究者的工作业绩和历史局限,认为在中国发现的东亚早期人类的新证据为探讨人类起源的单极和多极理论提供了新的可能;东亚人的古老性是目前科研工作的关键问题,必须利用各种手段,对此予以尽可能准确的界定。与中国学者合作研究人字洞遗址、龙骨坡遗址和东谷坨遗址的结果说明中国的考古遗址具有多样性,各遗址的石器相互间差异性很大,与同一时期非洲的模式不同,在这里可以找到更加有趣的材料来认识早期人类的方方面面,因此,应以最严谨的态度和最高的注意力对待中国的考古发现。此外,结合中国古人类、旧石器遗址和古气候学的研究资料,文章从宏观地理学的角度阐述了旧石器时代阿舍利和勒瓦娄哇两个典型的文化现象及其发展脉络,探讨了旧石器时代东亚和西亚之间的关系,对中国旧石器文化的发展模式及其与西亚乃至全球的关系提出了个人的独到见解;着眼于研究早期工业技术的发现地、创新地及其传播地点等问题认为,中国同西欧一样,在地理环境和人类生存方面都处于孤立无援的境地,其技术的发展亲历了在本土发明、从境外引进和向外输出等不同阶段,它们不愧是穿越时空来追随技术变革的两大实验场。文章