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1.
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2.
Summary The variations of the initialh E s height are investigated in the solar cycle 1957–1968, deriving the regressive dependency:h E s =121.4–6·10–2 R referring to the median monthly values at a solar zenith angle =75°. The similar variations ofh E s (R) during the day and night are interpreted as a domination of the sporadic layer formation from a redistribution of the day-time ionization and secondary participation of nightly ionizing sources. The analogous cyclich E s andh E variations confirm this conclusion while the seasonal variations in the state of the sporadic layer show outlined dynamical effects. The comparatively not big cyclic variation in the spatial state of theE-region are considered to confirm the predominating ionizing action of the ultraviolet range (933–1038 Å) in the lower part of theE-region, while the soft X-radiation influences mainly the near maximum part of this region.  相似文献   

3.
The Narmada-Son lineament (NSL) forms a major tectonic feature on the Indian subcontinent. The importance of this lineament lies in its evolution as well as its tectonic history. The lineament seems to have been active since Precambrian times. In order to understand the history of its evolution, it is necessary to know what igenous activity has been taking place along this lineament, and how the Deccan trap volcanics, which cover large areas along this lineament, have erupted.For the study of this problem an analysis of the aeromagnetic anomaly map lying between 76°15 to 77°30E and 21°45 to 22°50N has been carried out. Four different profiles (B 1 B 1,B 2 B 2,B 3 B 3 andB 4 B 4) have been drawn in N-S direction over this area and interpreted in terms of the intrusive bodies present within or below the surface of Deccan trap exposures. Inversion and forward modelling techniques have been adopted for interpretation purposes. An analysis of frequency spectra along the profiles has also been carried out to estimate the average depth of the different magnetic bodies. These results have been correlated with the available geological information. It has been found that most of the small wavelength anomalies are caused by dyke-like bodies within or below the Deccan trap at a depth of less than 0.5 km.  相似文献   

4.
A study of inertial scale gravity wave motions in the region of the atmosphere between 30 and 60 km has been undertaken, using wind and temperature data derived from rocket-borne falling sphere density experiments performed over Woomera, Australia between 1962 nad 1976. The gross features of the wave field compare favorably with those found in similar northern hemispheric studies. Wave propagation is found to be both vertically and horizontally anisotropic. A rotary spectral analysis indicates predominately upgoing wave energy, suggesting that the majority of sources of these waves lie below 30 km. A detailed statistical investigation of the waves, made using the Stokes parameters technique, reveals that phase progression is also highly directional in the horizontal, with a significant zonal component in summer, but with a strong meridional component in winter. Propagation towards the southeast is inferred in summer, with the waves possibly emanating from tropospheric sources in equatorial regions to the north of Australia. The technique also shows that, on average, the waves appear to have mean ellipse eccentricities (=f/) around 0.4–0.45. Indirect estimates of a number of important wave parameters are made. In particular,v andw flux estimates are made over several height intervals. The vertical gradient of density weighted flux implies wave-induced mean flow accelerations of the order 0.1–1 ms–1day–1. This suggests that dissipating gravity waves are a significant source of the momentum residuals that are encountered in studies of satellite data from this region.  相似文献   

5.
We have analysed a database of 300 h of tristatic ionospheric velocity measurements obtained overhead at Tromsø (66.3° magnetic latitude) by the EISCAT UHF radar system, for the presence of flow effects associated with the y-component of the IMF. Since it is already known that the flow depends upon IMF Bz, a least-squares multivariate analysis has been used to determine the flow dependence on both IMF By and Bz simultaneously. It is found that significant flow variations with IMF By occur, predominantly in the midnight sector (2100/0300 MLT), but also pre-dusk (1600/1700 MLT), which are directed eastward for IMF By positive and westward for IMF By negative. The flows are of magnitude 20/30 m s–1 nT–1 in the midnight sector, and smaller, 10/20 m s–1 nT–1, pre-dusk, and are thus associated with significant changes of flow of order a few hundred m s–1 over the usual range of IMF By of about ±5 nT. At other local times the IMF By-related perturbation flows are much smaller, less than 5 m s–1 nT–1, and consistent with zero within the uncertainty estimates. We have investigated whether these IMF By-dependent flows can be accounted for quantitatively by a theoretical model in which the equatorial flow in the inner magnetosphere is independent of IMF By, but where distortions of the magnetospheric magnetic field associated with a penetrating component of the IMF By field changes the mapping of the field to the ionosphere, and hence the ionospheric flow. We find that the principal flow perturbation produced by this effect is an east-west flow whose sense is determined by the north-south component of the unperturbed flow. Perturbations in the north-south flow are typically smaller by more than an order of magnitude, and generally negligible in terms of observations. Using equatorial flows which are determined from EISCAT data for zero IMF By, to which the corotation flow has been added, the theory predicts the presence of zonal perturbation flows which are generally directed eastward in the Northern Hemisphere for IMF By positive and westward for IMF By negative at all local times. However, although the day and night effects are therefore similar in principle, the model perturbation flows are much larger on the nightside than on the dayside, as observed, due to the day-night asymmetry in the unperturbed magnetospheric magnetic field. Overall, the model results are found to account well for the observed IMF By-related flow perturbations in the midnight sector, in terms of the sense and direction of the flow, the local time of their occurrence, as well as the magnitude of the flows (provided the magnetic model employed is not too distorted from dipolar form). At other local times the model predicts much smaller IMF By-related flow perturbations, and thus does not account for the effects observed in the pre-dusk sector.  相似文献   

6.
Summary The diffraction of a pressure wave arising from the edge of the floating ice due to an incident wave of the formH[t–(xcos/)+ (ysin/)], whereH(t) is the Heaviside step function, has been studied. The ice sheet has been taken to be moving with a velocity much less than the velocity of sound in the liquid. The problem has been solved using an approximate method of solving Wiener Hopf problems. Finally, the pressure field at a large distance from the edge has been derived in a closed form evaluating the integrals by the saddle point method.  相似文献   

7.
Summary The mean monthly precipitable water at four tropical stations Madras (13°00N, 80°11E), Waltair (17°42N, 83°18E), Bombay (18°54N, 72°49E) and Nagpur (21°06N, 79°03E) are evaluated for the layer surface to 500 mb (0–5.4 km) of the atmosphere using radiosonde data available for seven years period (1959–1965). The mean monthly precipitable water for the above four stations is also estimated from dew point temperature.The precipitable water in the air column at any station is examined in relation to monsoon flow. The higher values of precipitable water are found to occur over the regions when there is good supply of moisture by the monsoon flow as well as low level convergence. These studies are believed to provide useful information in forecasting the monsoon circulation over the country.  相似文献   

8.
The rocketsonde data obtained from the launchings made at Thumba (8°3215N, 76°5148E) during the winter period 1970–71, as already reported, have indicated that warmings of noticeable magnitude occurred at high levels (upper stratosphere and mesosphere) over this tropical station during the period mentioned. The mean monthly radiosonde temperatures of 50, 100 and 300 mb levels at Thumba (Trivandrum) and Delhi (28°35N, 77°12E) during the same period have also pointed out certain anomalies consistent with the warmings referred to above at Thumba. The radiosonde temperatures of the two stations, Thumba (Trivandrum) and Delhi, have now been examined, along with the values of total ozone, for the ten winter periods commencing from 1961–1962. The analysis has pointed out the possibility of high-level warmings also having occurred in the past over the Indian region during the winters of 1963–1964 and 1967–1968, which are also the periods when prominent warmings are definitely known to have occurred at higher latitudes. The behaviour of total ozone has been found to be different in the different years of the warmings. The features noticed have been presented and discussed.  相似文献   

9.
Résumé La première partie de l'article contient les résultats des mesures magnétiques, effectuées à Kaboul par Monsieur D.S.A.Adams et par l'auteur indépendamment. À cause du manque des instruments magnétiques de campagne, nous avons exécuté les mesures au moyen des appareils de laboratoire. On a obtenu les valeurs approximatives suivantes pour l'époque 1948.0 à Kaboul: et une variation séculaire de la déclinaison magnétique de—3 par an. Dans la deuxième partie l'auteur discute les mesures magnétiques exécutées dans la Province du Nord de l'Afghanistan et publiées parWeinberg etZimmermann. Les chiffres en question montrent une variation annuelle de la déclinaison magnétique en Turkestan Afghan de +1.0 jusqu'à –0.6, de 4.9 jusqu'à 6.0 pour l'inclinaison, et de –37 jusqu'à –52 pour la composante horizontale. L'auteur suppose que le terrain afghan soit anomral au point de vue magnétique et mentionne que certaines anomalies magnétiques ont été découvertes près d'Achkhabad, au voisinage de la frontière d'Iran, par les géologues Russes.  相似文献   

10.
The expression of equi-risk line derived by the authors represents the relationship between discharge capacityy 0 u and storage capacityz 0 u to keep flood frequency under a certain risk level represented by the return periodT, i.e.,z 0/z 0 u ={(y 0 u –y 0 u )/y 0 u } S , wherey 0 u andz 0 u areT-year probability peak discharge and total volume of a hydrograph. The shape parametersS is evaluated in this paper for various release rules of the storage facilities and correlations of durations and peaks of hydrographs. The expression forS is: , whereS 0 andS are the values ofS forp=0 and , andp is the exponent of a general storage-release relation,q=az' p, wherea is the storage constant, andz' andq are the volume of stored water and the corresponding release. The values ofS 0 andS are expressed in terms of the correlation coefficient of durations and peaks of inflow hydrographs.  相似文献   

11.
Summary Speeded-up magnetic tape recordings of earthquake signals can be analyzed by means of an electronic sound spectrograph. The time-dependent spectrum of body waves obtained through transient analysis provides some insight into the physical properties of the earth's interior. In the short-period arrivals traveling through the outer core and inner core dispersion has been observed. A group velocity maximum has been found forP at periods between 1 and 2 seconds. The direct rayPand the surface reflected phasePP convey more energy than the arrivalsP 2 andPcPP which, firstly, enter the outer core at incidence far from vertical, and secondly spend more time in the outer part of the fluid core.
Zusammenfassung Magnetbandaufzeichnungen von Erdbebensignalen können, mit vervielfachter Geschwindigkeit wiedergegeben, mittels eines elektronischen Schallspektrographen analysiert werden. Das zeitabhängige Raumwellenspektrum, das man aus einer solchen Analyse nichtstationärer Vorgänge erhält, gibt einen gewissen Einblick in die physikalischen Eigenschaften des Erdinnern. So wurde im kurzperiodischen Anteil der Raumwellen, die durch den äusseren und inneren Erdkern gelaufen sind, Dispersion beobachtet. BeiP wurde im Periodenbereich zwischen 1 und 2 Sekunden ein Gruppengeschwindigkeitsmaximum gefunden. Der direkte StrahlP und die einmal an der Erdoberfläche reflektiertePP-Welle transportieren mehr Energie als die WellenphasenP 2 undPcPP, die erstens in den äusseren Erdkern unter einem sehr grossen Inzidenzwinkel eindringen und zweitens eine längere Zeit benötigen, um den äusseren Teil des flüssigkeitsähnlichen Kerns zu durchlaufen.

Lamont Geological Observatory Contribution No. 558.  相似文献   

12.
Summary In adjusting measured values in sets A(r*), v(r*) and f(r*) by means of a power function in the form of P=Kr* a region of discontinuity of the approximating curves was found at the distance r*11.5 m kg –1/3. It is assumed that this discontinuity was caused by the varying character of the source of seismic waves. For scaled distances r*>11.5 m kg –1/3 the explosion was considered to be a spherical source from the point of view of the charge geometry and of the distance of the pick-up from the centre of the charge, whereas if r*<11.5 m kg –1/3 the explosion in the borehole had the character of a cylindrical source. The difference of the two types of sources was reflected in the exponent with both the functions A(r*) and v(r*), so that for r*>11.5 m kg –1/3 –4.0 and–2.4, and for r*<11.5 m kg –1/3 –2.5 and–1.5. For the same intervals of scaled distance in the set f(r*)1.4 and1.2.  相似文献   

13.
Summary The derivatives of the harmonicsP n (k) (sin O)cos kTO andP n (k) (sin O)sin kTO, occurring in the development of the lunar disturbing potential, are derived upto n=4 and for k== 0, 1, ..., n. The equatorial co-ordinates OTO are referred to the Moon's mass centre; the procedure for the solar disturbing potential is formally identical.  相似文献   

14.
In the present study the influence of smoke and sulfur dioxide concentrations and of wind velocity on the concentration of small positive and negative ions above Athens area (=37°58.3N, =23°43E,h=107 m) is examined.Between the above mentioned elements simple linear correlation and multiple linear correlation is attempted. This correlation is based on mean daily values of the elements, for the two-year period 1971–1972, for each month separately.From the above examination it has been ascertained that small ions concentration increases as smoke and/or sulfur dioxide concentration decreases. Also, small ions concentration increases as wind velocity increases.In addition, it was ascertained that sulfur dioxide contributes the least to the determination of the variance of small ions concentration, whilst the greatest contribution is made by smoke for the positive small ions or by wind velocity for the negative ones.  相似文献   

15.
The vertical geoelectric field measured at Vostok, Antarctica (78.5°S, 107°E, L=75.0) over the 13 month interval May 1979–May 1980 is correlated with the interplanetary magnetic field (IMF) components By and Bz at times when Vostok is connected to the dayside magnetosphere. No significant association with IMF Bx is found. The interaction of the solar wind and the Earth’s magnetic field generally results in anti-sunward plasma flow in the high-latitude, polar ionosphere driven by a dawn-to-dusk, cross polar cap potential difference pattern. Using the IZMEM model to infer the contribution of the cross polar cap potential difference to the potential difference between the ionosphere and the ground at Vostok for the measured IMF conditions, we show that this provides a viable mechanism for the IMF associations found. We demonstrate that the direct association of the geoelectric field with the cross polar cap potential difference is independent of a result (Park, 1976. Solar magnetic sector effects on the vertical atmospheric electric field at Vostok, Antartica. Geophysical Research Letters 3(8), 475–478) showing an 15% decrease in the vertical geoelectric field measured at Vostok, 1–3 days after the passage of IMF sector boundaries. Evidence is also presented supporting the Park result, for which a mechanism is yet to be confirmed.  相似文献   

16.
We estimate the response of chl-a (mg · m–3) to changes in concentrations of total phosphorus (TP) by calculating the slopeS = chl-a/TP in chl-a =f(TP) graphs. Results show that in years where algae are P-limited oligotrophic lakes respond less (median slope 0.21) to changes in nutrient concentrations than eutrophic lakes, (median slope 0.31) and these again less than hypereutrophic lakes, (median slope 1.02). We find no saturation value for the slope within the TP range considered (6–480 mg · m–3). Chl-a in eutrophic lakes responds more frequently to non-nutrient factors than oligotrophic and hypereutrophic lakes. Results obtained by replacing TP with a new nutrient parameter, TP = 0.056 · TP · IN0.226, in which inorganic nitrogen, IN, is factored in, suggest that nitrogen has an influence on chl-a in oligotrophic lakes. Blue-green algae respond less to changes in TP than other algal species, e.g., diatoms.  相似文献   

17.
Summary Utilising two years data collected at two tropical coastal stations, Madras (13°04N, 80°15E) and Waltair (17°42N, 83°18E) and for one tropical continental station, Nagpur (21°09N, 79°07E), the authors have re-evaluated the constants ofBrunt's regression equation. Analyses of the observations for Waltair and Nagpur show good correlation coefficients (r) between the values of the effective emissivity of the atmosphere (the effective emissivity is the ratio of incoming long-wave sky radiation at the surfaceR s , to black body radiation T 4) and the square root values of surface vapour pressuree (mb). The value ofr for Waltair from radiometer observations is 0.98. It is also determined for Waltair and Nagpur from Ångström compensation pyrgeometer observations as 0.83 and 0.91 respectively. A low correlation co-efficient 0.56 is obtained for Madras. It might be due to higher surface vapour pressure values at Madras than at Waltair and Nagpur. The applicability of the reduced regression equations are examined for different years for the different stations. The agreement between the computed values with the new regression equations and the observed long-wave sky radiation at the surface seems to be quite good.  相似文献   

18.
Zusammenfassung In den Jahren 1949 und 1950 sind am Niederrhein 4 Erdbeben gespürt worden. Von diesen war das Beben vom 8. März 1950 das stärkste. Im Herdgebiet, in der Nähe der Stadt Euskirchen, wurde die Stärke VII der Mercalli-Cancani-Sieberg-Skala erreicht. Die Auswertung der Seismogramme ergab als Epizentrum 50° 47, 6° 50 E (4 km östlich von Euskirchen). Die Herdtiefe ergab sich makroseismisch und mikroseismisch zu rund 6 km. Es werden Laufzeitkurven der Vorläuferwellen mitgeteilt. Die Schall-wahrnehmungen werden eingehend diskutiert und darauf hingewiesen, dass den mikroseismischen Verhältnissen dabei möglicherweise eine entscheidende Bedeutung zukommt.
Summary In 1949 and 1950 four earthquakes were felt on the Lower Rhine. Out of these the earthquake of March 3, 1950, was the strongest one. Near Euskirchen the intensity VII of the Mercalli-Cancani-Sieberg-Scale was atteined. The evaluation of the seismograms resulted the epicentre 50° 47 N, 6° 50 E (4 km E of Euskirchen). The microseismic and macroseismic data resulted a depth of the hypocentre of nearly 6 km. Curves of the arrival times ofP- andS-waves are given. Acustic phenomena are discussed and there is pointed out, that the microclimatic conditions may have a decisive signification.
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19.
Notes on the variation of magnetization within basalt lava flows and dikes   总被引：2，自引：0，他引：2  
Summary The magnetic properties of basaltic rocks are dominated by the contained primary Fe–Ti oxides. At solidus temperature (1000°C) the composition of these primary oxides is restricted to titanomagnetite (Fe3-xTixO4) and hemoilmenites (Fe2-yTiyO3). The examination of 269 chemical analyses of the primary Fe–Ti oxides in basalts (in sensu lato) gives an average ofx=0.61 (T c=168°C) for the titanomagnetites andy=0.89 (T c=–121°C) for the hemoilmenites. If distinction is made between tholeiites, alkali basalts and andesites, a clear difference for thex-values is observed: the average for tholeiitesx=0.64 (T c=144°C), for alkali basaltsx=0.52 (T c=253°C), for andesitesx=0.38 (T c=341°C).Environment of crystallization and cooling rate are major interrelated factors influencing subsequent changes in the mineralogy of the primary Fe–Ti oxides and resulting magnetic properties. This has been tested by studying the variation of magnetization and some of its parameters in three different basalt rock units: a dike, 180 cm, and two lava flows, 3 m and 33 m thick, respectively. Grain size and oxidation state of the titanomagnetites control the variation of magnetization in these basalt units.  相似文献   

20.
Summary An explicit solution is obtained for the system of equations describing the spheroidal motion in a homogeneous, isotropic, gravitating, elastic medium possessing spherical symmetry. This solution is used to derive the Green's dyad for a homogeneous gravitating sphere. The Green's dyad is then employed to obtain the displacement field induced by tangential and tensile dislocations of arbitrary orientation and depth within the sphere.Notation G Gravitational constant - a Radius of the earth - A o =4/3 G - Perturbation of the gravitational potential - Circular frequency - V p ,V s Compressional and shear wave velocities - k p =/V p - k s =/V s - k p [(2.8)] - , [(2.17)] - f l + Spherical Bessel function of the first kind - f l – Spherical Hankel function of the second kind - x =r - y =r - x o =r o - y o =ro - x =r k s - y =r k p - x o =r o k s - y o =r o k p - =a - =a - [(5.17)] - m, l   相似文献   

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