Aerosol concentrations and size distribution in the troposphere and lower stratosphere over Thumba

Rocket-borne ultraviolet photometers operating at =0.31 m have been used at Thumba (8°33N, 76°52E) to make measurements of atmospheric scattering at tropospheric and lower stratospheric altitudes. Measurements could be made of the amplitude of the scattered fluxes and the angular distribution up to an altitude of about 24 km on three rocket flights conducted as part of the 16 February 1980 solar eclipse campaign. These measurements have been used to study the size distribution as well as the number densities of aerosols in the troposphere and lower stratosphere over Thumba.     

Großkreisdifferenzgleichen

Summary Echo soundings of the U.S. Cruiser Milwaukee in the Puerto Rico Trough in 1939 are briefly discussed, and two depths of 30246 feet or 9219 m, found at 19° 36 N, 68° 20.5 W and at 19° 35N, 68° 8.75W, are stated to be the greatest depths which are known so far in the Atlantic Ocean.     

Studies on precipitable water over tropical stations in relation to monsoon flow

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.     

The magnetic observatory of Pendeli (Athens,Greece)

Summary A new magnetic observatory, named the Magnetic Observatory of Pendeli, was established and put in operation in 1958 near Athens (Greece). This Observatory was organized by and belongs to the Greek «Institute for Geology and Subsurface Research». The geographical position of the Pendeli Observatory is given by =38° 02.8, =23°51.8 andh=495 m (above sea level). The gemagnetic coordinates of the same are =36°.2, =102°.0. The Observatory is situated near Pendeli Mt. (18 km NEE of Athens). The site of the Observatory consists of marmor underlain by mica schists, both magnetically inactive.The building of the Observatory is constructed of stone and its roof made of tiles. The magnetograph room is in the underground of the building. The magnetic and thermal conditions in the variometer room are satisfactory enough.The variometers of the Observatory forH andZ are of the magnetic balance type. ForD a fibre suspension declinometer is used. The scale values of the variometers are _H =7.2 /mm, _D =1.0/mm (7.6 /mm), _Z =11.5 /mm. The speed of recording amounts to 12 mm/h and the width of the record is 9 cm.The Pendeli Observatory has been operating since April 1958. The record is changed every day. The scale and base-line values are determined every 10 days. The room for the absolute measurements is found in the ground floor of the building. A field magnetic theodolite is being used in the absolute measurements.D is measured with two magnets in a fibre suspension declinometer.H is measured by means of the deflection oscillation method and with a QHM as well. For the measurement ofI an earthinductor is available. The values of the magnetic elements are properly corrected in order to represent the external normal field.     

Chernobyl reactor accident consequences on small atmospheric ions concentration above Athens

In the present study the variation in small ion concentration (SIC), positive and negative, above Athens (=37°58.3N, =23°43E,h=107 m) after Chernobyl reactor accident is examined.SIC started to increase importantly at the National Observatory of Athens (N.O.A) since 3 May 1986 and reached its highest mean daily values on Monday, 5 May. These maximum values were 4 times the normal for positive ions and 5 times the normal for negative ions. Correlation coefficients were calculated between SIC and radionuclides I-131, Cs-137, Ru-103 and outdoor exposure rate.     

Estimation of long wave radiation by an empirical method

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.     

A preliminary study of thermally enhanced magnetic fabric in the Tertiary sediments from the Qaidam basin,NW China

Summary A preliminary observation has been made of the magnetic fabric in 14 specimens of undeformed sediment which exhibit repeatable principal orientation in undemagnetized state as well as after some steps of thermal demagnetization. They were chosen from 2000 specimens of the Tertiary formations of inland fluvio-lacustrine facies in the Qaidam basin, NW China. It was found that no large changes in magnetic fabric occur after stepwise thermal demagnetization up to 300°C, but some significant changes take place after treatment at higher temperature (500° up to 750°C). It is shown that the orientations of the 3 principal axes remain unchanged after each demagnetization step, whereas the differences between the principal values (L=K1–K2 and F=K2–K3) are greatly enhanced after high temperatures have been applied. The enhancement of L and F with no change in principal orientations facilitates the determination of the principal orientations. In our case one may easily measure the thermally enhanced magnetic lineation to estimate the palaeocurrent direction.Presented at 2nd conference on New Trends in Geomagnetism, Bechyn Castle, Czechoslovakia, September 24–29, 1990.     

High-level warmings and total ozone over a tropical region

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.     

Elektronenproduktion,Rekombination, Elektronendichte und Absorption in der ionosphärischenD-Region und ihre jahreszeitlichen Variationen

Zusammenfassung Es wird die Gleichung für die Elektronenproduktionq(z) abgeleitet, die die meteorologischen Elemente der Mesosphäre berücksichtigt. Nach Angaben über die mit Satelliten und Raketen gemessene Röntgenstrahlung mit 8 Å wird das Differentialspektrum des ionisierenden Energieflusses für eine mittlere Sonnenaktivität konstruiert. Auf dieser Grundlage und nach der bekannten Intensität der Strahlung Ly- sowie nach Angaben über dieElektronenproduktion der kosmischen Strahlung werden die Profileq _Rö(z),q _Ly-(z) undq _CR(z) für mittlere geographische Breiten und Standardatmosphäre entwickelt. Nach eingehender Analyse der vollständigen Gleichung für den effektiven Rekombinationskoeffizienten wird für die Verhältnisse in der tiefen Ionosphäre der Beitrag jeder einzelnen Komponente der Gleichung bestimmt. ist eine recht veränderliche Grösse, die von den aeronomischen und meteorologischen Verhältnissen und der Sonnenzenitdistanz abhängt. Aus den fürq(z) und (z) erhaltenen Angaben werden zwei ElektronendichteprofileN(z) für =30° und 75° erhalten. Das ProfilN(z) bei =30° wird mit dem gemittelten Profil einer umfangreichen Gruppe experimentell gefundener VerteilungenN(z) verglichen; das Profil bei =75° wird durch Messung der deviativen und nondeviativen Absorption für eine längere Zeitperiode überprüft. In beiden Fällen hat sich die Richtigkeit der theoretisch erhaltenen Profile bestätigt. Die jahreszeitlichen Variationen der nondeviativen Absorption in derD-Region sind ausschliesslich durch die Variationen der meteorologischen Parameter im Bereich der Mesopause bei konstantem Energiefluss der ionisierenden Strahlung bedingt.

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Summary An equation about the electron production is deduced in which the meteorological elements of the mesosphere are taken into account. The differential spectrum of the ionizing energy flux with 3 Å for average solar activity is constructed on evidence from rocket and satelitc measurements. The profilesq _Rö(z),q _Ly-(z) andq _CR(z) for mean geographical latitudes and standard atmosphere are plotted on that basis as well as on data fot the known intensity of the Ly- emission and the electron production of the cosmic rays. An exhaustive analysis is made of the full equation for the effective recombination coefficient and the contribution of all its components at lower ionosphere conditions is determined. is a rather variable quantity, dependent on the aeronomical and meteorological condition of the area under consideration, as well as on the solar zenith angle. Two profiles for the electron concentrationN(z) at =30° and 75° are drawn on the basis of data forq(z) and (z). The profileN(z) at =30° is compared with the averaged profile of a large group experimentally obtained distributionsN(z); the profile at =75° is checked by measurements of the deviative and nondeviative absorption taken for a lengthy period. Both checks are in good agreement with the theoretically obtained profiles. The seasonal variations of the nondeviative absorption in theD region could be completely explained with the variations of the meteorological parameters in the mesopause area at constant energy flux of the ionizing radiation.

     

Paleomagnetic study of satyavedu sandstones of cretaceous age from Andhra Pradesh,India

Summary The paleomagnetism of twenty six oriented samples of red sandstones from three different sites located in Satyavedu hills (near 13°30N, 79°55E) and belonging to coastal upper Gondwana formations of India has been studied. These sandstones have been considered to be equivalent of Tirupati sandstones of Lower to Middle Cretaceous age from Godavari valley on stratigraphic considerations. Consistent directions of magnetization were obtained from two different sites after stability tests. Results from one site gave ancient pole position at 26°N, 67°W, very close to that obtained for Tirupati sandstones, thus confirming the geologic correlation. Results from the second site were rejected on account of instability and those from the third site gave pole position at 79°48N, 76°58W. This site appears to have been remagnetized during Pleistocene times when there was large deposition of laterite in the area. Study of magnetic properties of these sandstones revealed that the magnetization was of the nature of CRM and the NRM was carried almost entirely by red coating on silica grains.N.G.R.I. Contribution No. 70-169.     

Cyclic variations of the initial height of the sporadicE-layer at middle geographical latitudes

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.     

Sunrise effects in the lowerD-Region by solar eclipse

Summary In contrast to the well known fact that the ionospheric absorption minimum falls behind the maximum phase of the solar eclipse, in the present work the reverse effect is discovered and analysed, namely that the ionospheric absorption minimum falls before the maximum phase of the eclipse, while the maximum absorption comes behind it. Such anomalies can be observed only on paths of long waves at oblique incidence of the layer (length of the path over 1300 km). The theoretical analysis shows that the established effects are due to the considerable increase of the factor of negative ions, respectively of the effective recombination coefficient in the first phase of the eclipse for heights between 65 and 70 km, i. e. in the lower boundary of theD-Region (CR-Layer). In the second phase of the eclipse falls rapidly because of which at a constant electron production inCR-layer a strong increase of the absorption is observed similar to the known sunrise effects in theD-Region. The electron drift is intensified about the maximum phase of the eclipse.     

La vitesse de phase des ondes de Rayleigh et les structures de la croûte et du manteau supérieur entre Machhad et Chiraz (Iran)

Résumé A partir de sismogrammes enregistrés dans deux stations sismologiques longues périodes identiques (WWSSS) installées à Machhad (36°1840N, 59°3516E) et à Chiraz (29°3040N, 52°3134E), la vitesse de phase des ondes de Rayleigh a été calculée dans cette région. D'après les résultats obtenus par l'étude des ondes de volume dans cette même région des modèles ont été établis. Le modèle s'accordant le mieux avec les résultats expérimentaux a une croûte d'environ 50 km d'épaisseur et comporte une couche à faible vitesse située entre 100 et 200–250 km de profondeur.     

The derivatives of the lunar disturbing potential harmonics with respect to euler's angles

Summary The derivatives of the harmonicsP _n ^(k) (sin _O)cos kT_O andP _n ^(k) (sin _O)sin kT_O, occurring in the development of the lunar disturbing potential, are derived upto n=4 and for k== 0, 1, ..., n. The equatorial co-ordinates _OT_O are referred to the Moon's mass centre; the procedure for the solar disturbing potential is formally identical.     

Analysis of aeromagnetic anomalies over the central part of the Narmada-Son lineament

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.     

Das rheinische Erdbeden bei Euskirchen am 8. März 1950

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.

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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.

     

The role of various ionization sources in the A3 lf radio-wave absorption in middle latitudes

Summary The 272 kHz ionospheric absorption has been measured at the Prhonice Observatory by the A3 method (oblique incidence) for a long period. The results of the comparison of these absorption data with indices of solar, geomagnetic and cosmic ray activity are presented for large solar zenith angles. The day-time absorption (x 75° – 85°) is described well by these indices and appears to be affected particularly by direct solar Lyman- radiation. The night-time absorption (x>100°), however, is not described sufficiently by the indices used.     

Some results of the comparison of Courvoisier,Schulze and Yanishevsky balancemeters

Summary Courvoisier, Schulze andYanishevsky type balancemeters have been compared in field exposure under different weather conditions and in the laboratory. Special attention has been devoted to the selectivity and the temperature regime of the detectors. The installation of the instruments is described and the main results of simultaneous measurements with the above-mentioned balancemeters are presented. , . v . .     

Analysis and optimization of wide-band force-balance seismometer responses

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On the problem of standardization of the magnitude-frequency relation

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