Ozone and airglow in the mesosphere region

The paper presents the results of a photometric study of the hydroxyl bands (7–2) and (8–3) in the night airglow spectrum at Mt. Abu in the winter and spring of 1966–1972. The observed nocturnal variation differs from the variation expected from the theoretical studies of Hesstvedt, Hunt, Shimazaki and others. Instead of a gradual fall in intensity after sunset to shortly before sunrise, a peak in intensity is found at a time which changes from month to month and roughly coincides with the transit times of the X-ray star TAU (XR-1)-Crab Nebula. Anexplanation of the observed phenomenon is offered in terms of the increased energy output into the D and E regions of the atmospheres, increased eddy diffusion, and production, of additional O(³P) and O₃ in the region 80–95 km. O₃ reacting with H gives rise to OH^*.     

Incoherent cerenkov radiation and its amplification via the landau instability

Quite often the VLF hiss powers recorded by space probes are some orders of magnitude greater than those predicted by the theory of incoherent Cerenkov radiation. In this note we suggest that the wavegrowth via the Landau instability might satisfactorily account for the disparity between the theory and experiment.     

Rare gases on the Earth and in meteorites

Analysis of abundance patterns of rare gases Ne²², Ar³⁶, Kr⁸⁴ and Xe¹³⁰ on Earth and in ordinary and carbonaceous chondrites is presented. A mechanism of chemical adsorption of rare gases at the planetesimal stage during their accretion is proposed to generate the abundance pattern of the heavy rare gases on the Earth. The calculated values for Xe and Kr agree well with the observed values whereas for Ar, the agreement is poor.     

Diffuse X-ray background measurements in the energy range 2–18 keV

Rocket measurements, of the diffuse X-ray background in the energy range 2–18 keV, conducted from Thumba Equatorial Rocket Launching Station (TERLS), India, are presented. The estimates of the cosmic background are derived by the method which employs the Earth and its atmosphere as a shutter to intercept the celestial X-rays. The results are shown to be consistent with a power law photon spectrum.13.6 _–3.3 ^+4.3 E ^{–1.73±0.15} photons/cm²-sec-keV-ster the spectrum being much flatter than that observed at higher energies.     

Salt and pepper cleaning on the landsat processed images

This paper proposes an algorithm for removing the unwanted pixels from the categorized Landsat data without disturbing the features in the categorized data. Sample outputs of the smoothed data and unsmoothed data (original data) are presented.     

中国地级以上城市土地经济密度差异的时空演化分析

以中国336个地级以上城市为研究对象,利用核密度估计和探索性空间数据分析方法,对2001~2014年中国地级以上城市土地经济密度差异的时空格局演化及影响因素进行分析和探讨。结果表明：① 中国地级以上城市土地经济密度的总体水平不断提高,平均值从2001年的4.769亿元/km²增加至2014年的15.375亿元/km²,但地区差距逐渐扩大;② 中国地级以上城市土地经济密度表现出显著的全局空间正相关性,相邻地市相互影响,呈现出“高–高”或“低–低”的空间集聚态势,且从LISA集聚图来看,城市土地经济密度通过空间聚类可以划分为“高水平均质型地域”、“塌陷型地域”、“极化型地域”和“低水平均质型地域”4种类型,不同地域类型的空间分布范围和稳定性等都存在差异;③ 中国地级以上城市土地经济密度冷、热点区域的空间分布具有相对稳定性,总体上表现出“东热西冷”的分布格局,热点区主要分布在东部的京津冀地区、长江三角洲地区和珠江三角洲地区等,广大中、西部地区则大多处于低值簇,属于城市土地经济密度的冷点区或次冷点区;④ 自然条件状况决定城市土地的供给能力和开发潜力,是导致中国地级以上城市土地经济密度差异的基础性因素,区域经济发展水平、经济发展政策、土地利用管理政策也会对城市土地经济密度差异造成一定程度的影响。     

300年来中国森林的变化

Based on historical documents, modern survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized. The forest area and forest coverage rates for each province of China from 1700 to 1949 are estimated backward by every 50 years. Linking the result with modern National Forest Inventory data, the spatial-temporal dynamics of Chinese forest in recent 300 years （AD 1700-1998） is quantitatively analyzed. The study shows that in recent 300 years, the forest area in current territory of China has declined by 0.95×10^8 hm^2 （or 9.2% of the coverage rate） in total, with a trend of decrease and recovery. Before the 1960s, there was a trend of accelerated descending. The forest area was reduced by 1.66×10^8 hm^2 （or 17% of the coverage rate） in 260 years. While after the 1960s, there has been a rapid increase. The forest area increased by 0.7×10^8 hm^2 （or 8% of the coverage rate） in 40 years. The study also shows that there is a significant spatial difference in the dynamics of forest. The amplitudes of increasing and decreasing in western China are both smaller than the ones in eastern China. During the rapid declining period from 1700 to 1949, the most serious decrease appeared in the Northeast, the Southwest and the Southeast, where the coverage rate in most provinces dropped over 20%. In Heilongjiang Province, the coverage rate dropped by 50%. In Jilin Province, it dropped by 36%. In Sichuan Province and Chongqing Municipality, it dropped by 42%. In Yunnan Province, it dropped by 35%. During the recovery period 1949-1998, the western provinces, municipality and autonomous regions, including Ningxia, Gansu, Inner Mongolia, Sichuan-Chongqing, Yunnan, Tibet, Xinjiang and Qinghai, etc, the increase rates are all below 5%, while the eastern provinces, municipality and autonomous regions （except Heilongjiang, Hubei, Jiangsu-Shanghai） have achieved an increase over 5%, among which the Guangdong-Hainan, Guangxi, Anhui, Beijing-Tianjin-H     

On the timing of the East Asian summer monsoon maximum during the Holocene—Does the speleothem oxygen isotope record reflect monsoon rainfall variability?

The evolution of the East Asian summer monsoon(EASM) during the Holocene has long been of significant interest.Knowledge of past EASM variability not only increases our understanding of monsoon dynamics on a long timescale,but it also provides an environmental and climatic background for research into Chinese cultural development.However,the timing of the EASM maximum remains controversial.The popular concept of an "early Holocene maximum" is mainly based on speleothemδ~(18)O(δ~(18)O_c) records from caves in southern China;however,the interpretation of δ~(18)O_C as a reliable proxy for EASM intensity is being increasingly challenged.The present paper is a critical review of the climatic significance of the δ~(18)O_C record from China.Firstly,we suggest that precipitation in northern China is an appropriate index of EASM intensity,the variation of which clearly indicates a mid-Holocene monsoon maximum.Secondly,an interregional comparison demonstrates that the precipitation record in northern China is quite different from that in southern China on a range of timescales,and is inconsistent with the spatial similarity exhibited by speleothem oxygen isotope records.Furthermore,both modeling and observational data show that the δ~(18)O_C records from southern China indeed reflect changes in precipitation δ~(18)O(δ~(18)O_P) rather than precipitation amount,and therefore that their use as an EASM proxy is inappropriate.Finally,we address several significant monsoon-related issues-including the driving mechanism of the EASM on an orbital timescale,the climatic significance of speleothem oxygen isotopes,and the relationship between atmospheric circulation and precipitation in monsoonal regions.     

Seismic bearing capacity of shallow strip footings

Seismic bearing capacity of shallow strip footings in soil has been obtained in the form of pseudo-static seismic bearing capacity factors N_cd, N_qd and N_d, denoting the cohesion, surcharge and unit weight components, respectively, by an extensive numerical iteration technique. Limit equilibrium method of analysis with composite failure surface is assumed. The validity of the principle of superposition is examined. Effects of both the horizontal and vertical seismic acceleration coefficients have been found to always reduce the ultimate bearing capacity significantly. Results obtained by the present method of analysis are compared with the available results and are found to be the least in the seismic case.     

富氟花岗岩中萤石岩浆成因的新证据

通过富氟花岗岩-HF-H2O体系的熔化-结晶实验,在620～700℃、1×108Pa条件下获得了石英+碱性长石+黄玉+云母+萤石的矿物组合.在该实验体系中首次发现了八面体萤石.实验结果表明,在岩浆条件下可以形成萤石,从而为富氟花岗岩中萤石的岩浆成因提供了新证据.