Experimental errors of measurements of vertical geomagnetic gradients in the stratosphere

The errors of measurements of vertical geomagnetic gradients at altitudes of 20–40 km, using a balloon magnetic gradiometer with a 6-km-long measuring base oriented along gravity, have been studied in the work. The errors related to the deviation of the measuring base position relative to the vertical have been studied during the real balloon flight with the help of the navigation GPS receivers. The deviations of the measuring base within 5°, which can sometimes reach 15°, have been obtained. This results in a decrease in the magnetic gradient measurement accuracy due to the errors introduced in the specification of the normal magnetic field used to detect magnetic anomalies. To eliminate this error, a GPS receiver was built in each magnetometer in order to observe magnetometers during synchronous measurements and to correct the measurements for the normal magnetic field. It has been indicated that the effect of deviations of the measuring base position on the results is not more than 2% of the measured value at such organization of a gradiometer.     

Interplanetary scintillations of strong radio sources in the descending phase near the cycle 23 minimum

Observations of interplanetary scintillations of the 3C 298 and 3C 48 radio sources during low solar activity, performed with a BSA FIAN radio telescope at a frequency of 111 MHz, are presented. The radial dependences of the scintillation indices, where the effect of a low-latitude heliospheric current sheet is observed, have been obtained. Based on the scintillation temporal spectra, the solar wind velocity values have been obtained, and it has been indicated that these values are in good agreement with those found using the spaced measurements method.     

Empirical model of variations in the continuum emission in the upper atmosphere. 1. Intensity

The ground-based and satellite measurements of the upper-atmosphere continuum (continuous emission) intensity in the visible and near IR spectral regions have been analyzed. The data were obtained at the geophysical stations, located in different regions of the globe, and at Mir Space Station. The regularities in the spectral distribution of the continuum emission intensity and emission variations have been revealed for different heliogeophysical conditions.     

Relation between the near-Earth electric field at high latitudes and intense cloud-to-ground lightning strokes initiating VLF emission bursts

Since 1998, the gradient of the near-Earth atmospheric electric field potential (|Ez|) has been continuously registered at Vostok Antarctic station within the scope of the joint Russian-Australian project. The data of the continuous 10-day period of fine weather in April 1998 have been selected for the following analysis. The field |Ez| behavior at Vostok station was compared with a number of lightning strokes obtained from data of the ground-based network of electromagnetic measurements. It has been found out that the average hourly values of |Ez| evidently negatively correlate with the number of intense lightning strokes. The causes of these relations are discussed. The obtained results are interpreted based on a theory of global electric circuit.     

The development of magnetic susceptibility anisotropy through crystallographic preferred orientation in a calcite rock

High-field torque-meter measurements of diamagnetic susceptibility anisotropy of a suite of samples of Carrara marble, axially shortened by amounts up to 50% at (1.5–3.0) · 10⁸ Pa confining pressure and at 20–500°C (mainly 400°C), have been compared with optical measurements of preferred crystallographic orientation. A revised value for the susceptibility anisotropy of calcite has been obtained from studies of single crystals, and it has been shown to be almost independent of the state of intracrystalline plastic strain. From the measured anisotropy of calcite, quantitative comparison of optical and magnetic fabric measurements is possible. It is found that these measurements agree and the implications of the observed progressive development of fabric intensity with strain are discussed.     

A model study of the temporal behaviour of the emission intensity and rotational temperature of the OH Meinel bands for high-latitude summer conditions

The temporal variation of OH* emission and weighted rotational temperature has been studied for high-latitude summer conditions. Observations for 60°N latitude show OH weighted temperatures that always exceed 145 K even during periods of noctilucent clouds. Using a one-dimensional model the effects in excited OH concentration produced by changes in temperature, eddy diffusion, and water concentration have been analysed. We are forced to conclude that there remains a discrepancy between the OH temperatures predicted by the model and that obtained from OH^* measurements. An increase in OH^* concentration from June to the beginning of August, followed by a slow decrease during August has been obtained in agreement with the measurements. The 16-day modulation present in the measurements was simulated in a simple manner by varying the temperature in the mesopause region. This variation produces periodic modulations in both OH^* concentration and weighted temperature of 16 days. The results show the temperature leading the OH^* column concentration by three days. This phase shift is also present in the observations.     

Neogene aquifer properties specified through the interpretation of electrical sounding data,Salamiyeh region,central Syria

Twenty‐nine Schlumberger electrical soundings were carried out in the Salamiyeh region in Syria using a maximum current electrode separation of 1 km. Three soundings were made at existing boreholes for comparison. Aquifer parameters of hydraulic conductivity and transmissivity were obtained by analysing pumping test data from the existing boreholes. An empirical relationship between hydraulic conductivity determined from the pumping test and both resistivity and thickness of the Neogene aquifer has been established for these boreholes in order to calculate the geophysical hydraulic conductivity. A close agreement has been obtained between the computed hydraulic conductivity and that determined from the pumping test. The relationship established has, therefore, been generalized in the study area in order to evaluate hydraulic conductivity and transmissivity at all the points where geoelectrical measurements have been carried out. This generalization allows one to derive maps of the hydraulic conductivity and transmissivity in the study area based on geoelectrical measurements. These maps are important in future modelling processes oriented towards better exploitation of the aquifers. Copyright © 2006 John Wiley & Sons, Ltd.     

Comparison of ground-based and satellite measurements of atmospheric temperature in the mesopause region in high-latitude eastern Siberia

The mesopause kinetic temperature at an altitude of 87 km measured with a SABER broadband radiometer installed on the TIMED satellite and the hydroxyl molecule rotational temperature measured with a ground-spectrograph installed in high-latitude eastern Siberia (Maimaga optical station; φ = 63°N, λ = 129.5°E) are compared. The data of the observations performed from 2002 to 2006 have been analyzed. The temperatures measured during the satellite passes at distances not larger than 300 km from the intersection of the spectrograph sighting line with the hydroxyl emitting layer (∼87 km) have been compared. An analysis of 130 cases of coincident measurements indicated that the average hydroxyl molecule rotational temperatures are systematically lower than the average kinetic temperature at an altitude of the hydroxyl layer measured with SABER by 4.4 K (with a standard deviation of 11.4 K). A seasonal dependence is observed regarding the difference between the ground-based and satellite measurements. The difference decreases from 10 K in January to zero towards March. However, the time variations in the temperature obtained with the ground-based device and on the satellite are similar. Based on the performed analysis, it has been concluded that a series of hydroxyl rotational temperatures can be used to study temperature variations on different time scales, including long-term trends at the temperature emission altitude (∼87 km).     

On the evaluation of solar radiation in Egypt

Summary A study of the depletion of solar radiation at Helwan Observatory has shown, for Egypt, that:a) Diffuse reflexion and absorption by suspended particles in the atmosphere constitute about 20 percent of the total depletion;b) Absorption by water vapour is the only factor that should be evaluated at any place to give an estimation of the solar radiation received at that place. This can be obtained either from the mean values of the surface water vapour pressure which have been considered in detail, or, for individual cases, from spectroscopic measurements of the precipitable water content whose daily variations have been studied.     

Spatial and temporal variations in infrared emissions of the upper atmosphere. 1. Atomic oxygen (λ 63 μm) emission

Rocket and balloon measurement data on atomic-oxygen (λ 63 µm) emission in the upper atmosphere are presented. The data from the longest (1989–2003) period of measurements of the atomic-oxygen (λ 63 µm) emission intensity obtained by spectral instruments on sounding balloons at an altitude of 38 km at midlatitudes have been systematized and analyzed. Regularities in diurnal and seasonal variations in the intensity of this emission, as well as in its relation with solar activity, have been revealed.     

On the remote sensing of plasma sheet from low-altitude spacecraft

The possibility to estimate plasma sheet parameters from low-altitude measurements looks quite attractive, but it critically depends on how isotropic the plasma pressure is in the flux tube. To evaluate the ion pressure anisotropy we compare the values of pressure in the ionospheric and equatorial parts of the field line. Ionospheric values were computed from proton measurements at NOAA low-altitude satellites, they were compared with pressure estimates computed from empirical magnetic field models as well as with average values known from direct plasma sheet measurements. Three different methods of mapping the plasma pressure from plasma sheet to low altitude have been tried; each uses the particle isotropic boundaries observed at low altitudes and/or computed from magnetospheric models. Excluding observations obtained during substorm expansion, from these comparisons we conclude that in the plasma sheet, at geocentric distances 9–20R_E, the pressure estimates in the ionospheric and equatorial parts of the plasma sheet flux tube agree very well, suggesting a good pressure isotropy and thus justifying a possibility to monitor the plasma sheet parameters based on low-altitude measurements. The results also illustrate the usefulness of isotropic boundaries as a label of tail current intensity and as reliable tool for establishing mapping between magnetosphere and ionosphere.     

Spatial and temporal variations in infrared emissions of the upper atmosphere. 2. 15-μm carbon dioxide emission

The results of rocket and satellite measurements of carbon dioxide emissions at a wavelength of 15 μm in the upper atmosphere have been systematized and analyzed. Analytical expressions describing the dependence of the altitude distribution of 15-μm CO₂ emission intensity and its variation in the altitude range from 100 to 130 km on the season, latitude, and solar activity have been obtained.     

Evaluation of wind effects on a supertall building based on full‐scale measurements

This paper describes the results obtained from the full‐scale measurements of wind effects on a 70‐storey building in Hong Kong. The building which has a height of approximately 370 m is the second tallest structure in Hong Kong. The field data such as wind speed, wind direction and wind‐induced acceleration responses have been measured since 1995 including the close passage of two typhoons; typhoon Sally and typhoon Kent. Detailed analysis of the field data is conducted. The full‐scale measurements are compared with the wind tunnel results obtained in the Boundary Layer Wind Tunnel Laboratory at Western Ontario University. The amplitude‐dependent characteristics of damping and natural frequency that were obtained by using the random decrement technique are investigated. Copyright © 2000 John Wiley & Sons, Ltd.     

Upper-mantle conductivity determined by the geomagnetic lunar daily variation

The geomagnetic lunar daily variation, and the solar daily variation, have been recently analysed by Malin. The response measurements that he obtained are used here to investigate the radial distribution of electrical conductivity in the upper mantle. It is found that these observed response measurements require low conductivity in the mantle, at least as far down as 650 km from the surface. This result is compatible with the conductivity models determined by the quiet-day daily variation, and so justifies the use of these variation fields for geomagnetic deep sounding.     

Effect of solar flares in radiochemical measurements of solar neutrino intensity

The effect of chromospheric flares at the end of the exposure has been studied for all radiochemical facilities measuring the flux of solar neutrino. For chlorine-argon measurements (Brookheaven), it has been found that the development of flared results in the count rate acceleration to 4.7 ± 1.2 SNU. The effect of this growth is fictitious; this is an increase in the effectiveness of reaction product extraction from the target matter under the action of the ULF electromagnetic disturbance induced by the flare X-rays rather than an increase in the flux. The indications that a similar effect is present in the SAGE gallium-germanium measurement have been obtained. For the GALLEX gallium-germanium experiment, the effect of flares has not been found; the sign of this effect possibly differs from that of the Brookheaven and SAGE measurements. The found difference agrees with the conclusion that the results of the SAGE and GALLEX measurements anticorrelate for the exposures that end simultaneously.     

用云南下关测点的水压致裂结果分析地形起伏对应力测值的影响

本文以云南下关黄草坝的水压致裂应力测量结果为例,讨论了地形起伏对云南区应力测值的影响。结果表明,地形起伏对应力测值的绝对影响随深度的增加衰减缓慢,相对影响急剧减小。100米以内深度的应力测量,地形影响可能给测值带来10%以上的误差。云南区的水压致裂应力测量深达500米,是可以排除掉地形起伏的影响的。     

Hydrology of Blue Lake in the Dinaric karst

The aim of this paper is to analyse hydrological measurements obtained from Blue Lake located near the town of Imotski (Croatia), during the period from 6 November 2009 at 10:26 h to 4 September 2010 at 03:26 h (7230 h or 302 days). The water depth, water temperature and electrical conductivity of the water were continuously measured during this period. The measurements were obtained with a CTD DIVER (Schlumberger Water Services). The instrument was fixed at the bottom of Blue Lake, which means that all the measured data refer to a single point of measurement. The data represent the first systematic and continuous monitoring of the hydrological parameters of this fascinating karst phenomenon. The hydrological analysis also involved daily rainfall data and daily mean air temperatures recorded at the nearby Imotski meteorological station. The rate of water level rise and fall and the hourly and daily average inflow and outflow into and from the lake were calculated using the available data. The analysis led to the conclusion that Blue Lake is mainly recharged by water coming from the karst aquifer, the dimensions and the characteristics of which have not yet been adequately studied. Copyright © 2013 John Wiley & Sons, Ltd.     

首都圈地区地震重力测量数据的统一处理与分析

对首都圈地区由不同施测单位用不同仪器或不同方法获得的三组重力测量数据,通过绝对和相对测量的联合平差、相对测量结果的系统差消除,建立起绝对的、统一的重力时变体系;在此基础上分析了非构造因素地壳沉降的影响,并进行了测点位移改正,消除了长波干扰;实现了绝对和相对测量方法优势互补、消除矛盾和环境干扰、扩大信息量、加密时域采样间隔等目的,提高了识别构造活动过程的能力．结果表明,两组相对测量数据之间以及其中的10期观测资料中存在系统误差,研究区东南部的非均匀性局部地壳下沉导致10个点重力值线性上升,本文用回归分析的方法进行了改正．改正后的重力时变图对1995年10月6日古冶5.0级地震有明显而完整的反映．      

V S Profiles from Noise Cross Correlation at Local and Small Scale

Ambient noise measurements have been performed at local and small scales in the Neapolitan and surrounding areas (Campania, southern Italy) by employing two broad-band Kinemetrics Q330 stations, equipped with Episensor ES-T three component accelerometers. In both experiments frequency time analysis (FTAN method) has been performed on the vertical and radial components of noise cross correlations to retrieve the Rayleigh wave dispersion (Green??s function). At local scale, over an interstation distance of about 26?km, the group velocity dispersion values have been compared with those obtained from FTAN analysis on recordings of two earthquakes with similar path. At small scale, measurements have been carried out over an interstation distance of about 440?m in the public gardens of Scampia, the northernmost quarter of Naples. The Rayleigh wave group velocity dispersion data obtained from noise cross correlation, have been combined with those from active seismic experiment along the same alignment, but shorter (120?m offset). The non linear inversion of such a dispersion curve has allowed the definition of V _S models to depths of 100?m, in agreement with nearby stratigraphy. Moreover, a good agreement has resulted for the resonance frequency among the H/V ratio, the ellipticity of the fundamental mode computed for the chosen V _S model, and the average two-dimensional (2D) spectral amplification computed along a cross section representative of the Scampia quarter.     

Application of the integrated NMR-TDEM method in groundwater exploration in Israel

The Nuclear Magnetic Resonance (NMR) method is the only physical tool currently available which is able to detect directly the presence of fresh water in the subsurface. The Time Domain Electromagnetic (TDEM) method, in turn, has been proven highly efficient in detecting saline groundwater. The combined application of these two methods is the most promising way to delineate accurately groundwater-bearing aquifers and to evaluate the quality of the water. This idea was tested during the feasibility study carried out under different hydrogeological conditions throughout Israel during August–September 1992. The Russian Hydroscope and Geonics PROTEM-IV instruments were used for the NMR and TDEM measurements, respectively.A total of 36 NMR and 12 TDEM stations was established, mostly in close proximity to existing observation wells. Among these only 19 NMR measurements showed reasonable signal-to-noise characteristics, while the rest were obviously distorted by ambient noise. The number of distorted measurements could have been even greater had they been carried out at all points planned. However, a significant number of the NMR stations were cancelled due to their proximity (less than 1–1.5 km) to electric power lines. As a result almost the entire Mediterranean coast of Israel, which was originally chosen as the main test site for this survey, turned out to be unsuitable owing to the low ambient noise protection of the Hydroscope. Another serious limitation of NMR measurements is the maximum penetration depth. The deepest information obtained during the feasibility study was from a depth of 74 m.Nevertheless, within the framework of its applicability, the NMR measurements proved to be sufficiently accurate and to have a high resolving capability. A comparison with the borehole data shows that, in most cases, NMR is able not only to detect the presence of water, but also to delineate different subaquifers. At the same time, however, the transmissivity and aquifer texture are much less reliably detected. The combined application of the NMR and TDEM methods may essentially improve the reliability of the interpretation. In all cases where the NMR anomaly fits the drop in TDEM resistivity, water of a different salinity is found at approximately the same depth. A reasonable correlation between the interpreted resistivities and water salinities is obtained for these horizons. However, if only one method indicates the presence of water, this, in many cases, was not confirmed by the borehole data. The TDEM anomalies were obviously caused by low-resistivity lithologies, while some of the false NMR signals could be explained by a low signal-to-noise ratio.As regards the freshwater/seawater interface, this was, in all cases, accurately detected by the TDEM measurements alone. It is interesting to note that at the same depth, NMR measurements indicated a drastically increasing anomaly followed by the absence of water at greater depths. The latter can most likely be explained by the very low resistivity of the sea water, which is not taken into account by the existing NMR interpretation.