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1.
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   

2.
Summary Studies of various radiation fluxes, namely solar radiation, albedo (reflection coefficient), long-wave radiation of the earth and the atmosphere and net radiation observed at a tropical station are presented in this paper. The time variation of these fluxes are examined in relation to various meteorological parameters and atmospheric conditions.The constants of the general radiation balance equation are determined. The calculated radiation balance equation with new constants for the station isR=0.86 (1–)S–4.2. A high correlation coefficient 0.99 is obtained between net short-wave radiation (1–)S and net radiationR. The radiation balance at a tropical station is evaluated. It is found over a year there is a net surplus of 94 kilo-langleys.  相似文献   

3.
Fault dimensions,displacements and growth   总被引：15，自引：0，他引：15  
Maximum total displacement (D) is plotted against fault or thrust width(W) for 65 faults, thrusts, and groups of faults from a variety of geological environments. Displacements range from 0.4 m to 40 km and widths from 150 m to 630 km, and there is a near linear relationship betweenD andW 2. The required compatibility strains (e s) in rocks adjacent to these faults increases linearly withW and with and ranges frome s=2×10–4 toe s=3×10–1. These are permanent ductile strains, which compare with values ofe s=2×10–5 for the elastic strains imposed during single slip earthquake events, which are characterised by a linear relationship between slip (u) andW.The data are consisten with a simple growth model for faults and thrusts, in which the slip in successive events increases by increments of constant size, and which predicts a relationship between displacement and width of the formD=cW 2. Incorporation of constant ductile strain rate into the model shows that the repreat time for slip events remains constant throughout the life of a fault, while the displacement rate increases with time. An internally consistent model withe s=2×10–5, giving repeat times of 160 years and instantaneous displacement rates of 0.02 cm/yr, 0.2 cm/yr, and 2.0 cm/yr when total displacement is 1 m, 100 m, and 10 km, and slip increasing by 0.5 mm with each event, gives a good approximation of the data. The model is also applicable to stable sliding, the slip rate varying with ductile strain rate and withW 2.  相似文献   

4.
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   

5.
Summary Studies of various fluxes, namely net radiation, soil heat, sensible heat and latent heat observed at a tropical station are presented in this paper. The time variation of these fluxes are examined in relation to various meteorological parameters and atmospheric conditions. The turbulent transfer coefficients have been evaluated to examine the applicability of the classical theory or the non-equivalence theory for eddy transport in the lower layers of the atmosphere. The energy balance at a tropical station is evaluated. It is found over year there is a net surplus of 94,000 ly. A detailed discussion of the disposal of this energy by various consuming processes is given.Symbols and notation All the quantities represented by symbols in the text of the paper are defined below C p specific heat at constant pressure in cal. g–1 °K - E evaporation in g cm–2 hr–1 - E * evaporative heat flux cal. cm–2 sec–1 (in Eq. 10) - e vapour pressure in millibars - e z ,e 2z vapour pressure at heightsz and 2z - g acceleration due to gravity - H sensible heat flux cal cm–2 sec–1 (in Eq. 12) - K M ,K H ,K W coefficients of eddy diffusivities of momentum, heat, and water vapour respectively in cm2 sec–1 - k von Karman' constant=0.4 - L Monin-Obukhov length (according to Monin and Obukhov [53] the structure of the turbulent boundary layer is determined by the non-dimensional variableZ/L whereL is defined byL=–(u * 3 C p T)/(kgH) - ly langleys - Q c Q—sensible heat flux in langleys (in Eqs. 3 and 4) - Q e E—latent heat flux in langleys (in Eqs. 3 and 4) - Q s S—soil heat flux in langleys (in Eqs. 3 and 4) - Q i Q c +Q e +Q s whenK M K H K W , (in Eq. 6) - Q' i Q' c +Q' e +Q s whenK M =K H =K W (in Eq. 7) - qq mean specific humidity g kg–1  相似文献   

6.
Strong motion (SM) data of six Mexican subduction zone earthquakes (6.4M S8.1) recorded near the epicentral zone are analyzed to estimate their far-field source acceleration spectra at higher frequencies (f0.3 Hz). Apart from the usual corrections such as geometrical spreading (1/R), average radiation pattern (0.6), free surface amplification (a factor of 2), and equal partitioning of the energy into two orthogonal horizontal components (a factor of 1/ ), the observed spectra are corrected for a frequency dependentQ(Q=100f), a site dependent filter (e –kf ), and amplification ofS waves near the surface (a factor of about 2 atf2Hz). We takeR as the average distance from the rupture area to the site. If we model the high frequency plateau (f1 Hz) of the source spectra, by a point source –2-model, and interpret them in terms of Brune's model we obtain between 50 and 100 bars for all earthquakes. The low-frequency broadband teleseismicP wave spectra, corrected witht *=1.0 s, agrees within a factor of two with SM source spectra near 1 Hz. The –2-model is inadequate to explain the observed source spectra in a broad frequency range; these resemble spectra given byGusev (1983) with some differences.SM source acceleration spectra require significant corrections to explain observed spectra and RMS acceleration (arms) (a) at farther coastal sites for extended sources due to directivity effect and (b) at inland sites (100R200 km) because of unaccounted path and site amplification and/or invalidity of body-wave approximation. The observed spectra and arms at these sites are significantly greater than the predicted values from the estimated source spectra.  相似文献   

7.
The authors conducted a Rn222 survey in wells of the Larderello geothermal field (Italy) and observed considerable variations in concentrations. Simple models show that flow-rate plays an important part in the Rn222 content of each well, as it directly affects the fluid transit time in the reservoirs. Rn222 has been sampled from two wells of the Serrazzano area during flow-rate drawdown tests. The apparent volume of the steam reservoir of each of these two wells has been estimated from the Rn222 concentration versus flow-rate curves.List of symbols Q Flow-rate (kg h–1) - Decay constant of Rn222 (=7.553×10–3 h–1) - Porosity of the reservoir (volume of fluid/volume of rock) - 1 Density of the fluid in the reservoir (kg m–3) - 2 Density of the rock in the reservoir (kg m–3) - M Stationary mass of fluid filling the reservoir (kg). - E Emanating power of the rock in the reservoir (nCi kg rock –1 h–1). - P Production rate of Rn222 in the reservoir: number of atoms of Rn222 (divided by 1.764×107) transferred by the rock to the mass unit of fluid per unit time (nCi kg fluid –1 h–1). - N Specific concentration of Rn222 in the fluid (nCi kg–1) - Characteristic time of the steam reservoir at maximum flow-rate (=M/Q)  相似文献   

8.
The dependence of peak ground acceleration and velocity on seismic moment is studied for a set of small earthquakes (0.7<M L<3.2) recorded digitally at distances of a few km in the Campi Flegrei volcanic area near Naples, Italy, during the ground uplift episode of 1982–1984. Numerical simulations, using the -square spectral model with constant stress drop and ane –kf high frequency decay, fit well both the velocity and acceleration data for an averagek=0.015. The observed ground motions in the 1–24 Hz frequency band appear to consist of radiation from simple sources modified only slightly by attenuation effects. Moreover, the scaling of peak values agrees closely with those determined in nonvolcanic areas, once the difference in stress drop is taken into account.  相似文献   

9.
Sakhalinskii Shelf information and analytical GIS based on observational data is used to simulate hydrological parameter values at standard horizons of stationary stations in the La Perouse Strait. The spatial and temporal distribution pattern for oceanographic parameters has been obtained. Water masses and water structures have been identified using classic T, S-analysis. Volumetric T, S-analysis of waters is used to evaluate the volumes, heat content, and salinity of the water masses chosen. For the first time, information for the winter season, which is the least investigated season and for which no generalizations whatsoever have been made until the present, has been obtained.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 18–27.Original Russian Text Copyright © 2005 by Pishchalnik, Arkhipkin, Leonov.  相似文献   

10.
Summary In this study, values of the Ångström turbidity coefficient () determined from Solar radiation observations at the National Observatory of Athens over the period 1955–1972 are analysed. Mean daily turbidity lies between 0.020–0.100. Turbidity is higher in summer than in winter. The main factor determining the turbidity is the air mass type. The scavenging by rainfall probably has a considerable effect in determining this distribution. There is some evidence of a trend of increasing turbidity during the period.  相似文献   

11.
Janle  P.  Meissner  R. 《Surveys in Geophysics》1986,8(2):107-186
Geo-scientific planetary research of the last 25 years has revealed the global structure and evolution of the terrestrial planets Moon, Mercury, Venus and Mars. The evolution of the terrestrial bodies involves a differentiation into heavy metallic cores, Fe-and Mg-rich silicate mantles and light Ca, Al-rich silicate crusts early in the history of the solar system. Magnetic measurements yield a weak dipole field for Mercury, a very weak field (and local anomalies) for the Moon and no measurable field for Venus and mars. Seismic studies of the Moon show a crust-mantle boundary at an average depth of 60 km for the front side, P- and S-wave velocities around 8 respectively 4.5 km s–1 in the mantle and a considerable S-wave attenuation below a depth of 1000 km. Satellite gravity permits the study of lateral density variations in the lithosphere. Additional contributions come from photogeology, orbital particle, x-and -ray measurements, radar and petrology.The cratered surfaces of the smaller bodies Moon and Mercury have been mainly shaped by meteorite impacts followed by a period of volcanic flows into the impact basins until about 3×109 yr before present. Mars in addition shows a more developed surface. Its northern half is dominated by subsidence and younger volcanic flows. It even shows a graben system (rift) in the equatorial region. Large channels and relics of permafrost attest the role of water for the erosional history. Venus, the most developed body except Earth, shows many indications of volcanism, grabens (rifts) and at least at northern latitudes collisional belts, i.e. mountain ranges, suggesting a limited plate tectonic process with a possible shallow subduction.List of Symbols and Abbreviations a=R e mean equatorial radius (km) - A(r, t) heat production by radioactive elements (W m–3) - A, B equatorial moments of inertia - b polar radius (km) - complex amplitude of bathymetry in the wave number (K) domain (m) - C polar moment of inertia - C Fe moment of inertia of metallic core - C Si moment of inertia of silicate mantle - C p heat capacity at constant pressure (JK–1 mole–) - C nm,J nm,S nm harmonic coefficients of degreen and orderm - C/(MR e 2 ) factor of moment of inertia - d distance (km) - d nondimensional radius of disc load of elastic bending model - D diameter of crater (km) - D flexural rigidity (dyn cm) - E Young modulus (dyn cm–2) - E maximum strain energy - E energy loss during time interval t - f frequency (Hz) - f flattening - F magnetic field strength (Oe) (1 Oe=79.58A m–1) - g acceleration or gravity (cms–2) or (mGal) (1mGal=10–3cms–2) - mean acceleration - g e equatorial surface gravity - complex amplitude of gravity anomaly in the wave number (K) domain - g free air gravity anomaly (FAA) - g Bouguer gravity anomaly - g t gravity attraction of the topography - G gravitational constant,G=6.67×10–11 m3kg–1s–2 - GM planetocentric gravitational constant - h relation of centrifugal acceleration (2 R e ) to surface acceleration (g e ) at the equator - J magnetic flux density (magnetic field) (T) (1T=109 nT=109 =104G (Gauss)) - J 2 oblateness - J nm seeC nm - k (0) (zero) pressure bulk modulus (Pa) (Pascal, 1 Pa=1 Nm–2) - K wave number (km–1) - K * thermal conductivity (Jm–1s–1K–1) - L thickness of elastic lithosphere (km) - M mas of planet (kg) - M Fe mass of metallic core - M Si mass of silicate mantle - M(r) fractional mass of planet with fractional radiusr - m magnetic dipole moment (Am2) (1Am2=103Gcm3) - m b body wave magnitude - N crater frequency (km–2) - N(D) cumulative number of cumulative frequency of craters with diameters D - P pressure (Pa) (1Pa=1Nm–2=10–5 bar) - P z vertical (lithostatic) stress, see also z (Pa) - P n m (cos) Legendre polynomial - q surface load (dyn cm–2) - Q seismic quality factor, 2E/E - Q s ,Q p seismic quality factor derived from seismic S-and P-waves - R=R 0 mean radius of the planet (km) (2a+b)/3 - R e =a mean equatorial radius of the planet - r distance from the center of the planet (fractional radius) - r Fe radius of metallic core - S nm seeC nm - t time and age in a (years), d (days), h (hours), min (minutes), s (seconds) - T mean crustal thickness from Airy isostatic gravity models (km) - T temperature (°C or K) (0°C=273.15K) - T m solidus temperature - T sideral period of rotation in d (days), h (hours), min (minutes), s (seconds), =2/T - U external potential field of gravity of a planet - V volume of planet - V p ,V s compressional (P), shear (S) wave velocity, respectively (kms–1) - w deflection of lithosphere from elastic bending models (km) - z, Z depth (km) - z (K) admittance function (mGal m–1) - thermal expansion (°C–1) - viscosity (poise) (1 poise=1gcm–1s–1) - co-latitude (90°-) - longitude - Poisson ratio - density (g cm–3) - mean density - 0 zero pressure density - m , Si average density of silicate mantle (fluid interior) - average density of metallic core - t , top density of the topography - density difference between crustal and mantle material - electrical conductivity (–1 m–1) - r , radial and azimuthal surface stress of axisymmetric load (Pa) - z vertical (lithostatic) stress (seeP z ) - II second invariant of stress deviation tensor - latitude - angular velocity of a planet (=2/T) - ages in years (a), generally 0 years is present - B.P. before present - FAA Free Air Gravity Anomaly (see g - HFT High Frequency Teleseismic event - LTP Lunar Transient Phenomenon - LOS Line-Of-Sight - NRM Natural Remanent Magnetization Contribution No. 309, Institut für Geophysik der Universität, Kiel, F.R.G.  相似文献   

12.
Seismologically determined properties of the 400 km discontinuity may be compared to experimentally determined properties of the associated phase transformation in order to place constraints upon upper mantle bulk composition. Disagreement among previous studies is commonly ascribed to differences in elastic equations of state (especially to assumptions about pressure and temperature derivatives) between studies. However, much of the disparity between studies is actually due to the selection of different seismic data functionals (P-wave velocity,S-wave velocity, etc.) for comparison to minnral clasticity calculations, rather than to the differences in elasticity data sets and equations of state. Within any given study, bulk sound velocity comparisons generally yield more olivine-rich compositional estimates than doP-wave velocity comparisons, which in turn indicate more olivine thanS-wave velocities. Indeed, such variation in compositional estimates within a given study (arising from choice of data functional) exceeds the variation between studies (arising from elastic equation of state approx mations). it can be argued that bulk sound velocities are better constrained seismologically than densities and, being independent of assumptions about shear moduli, should provide more reliable compositional estimates thanP-orS-wave velocities.Using recently measured bulk and shear moduli equations of state, mutually consistent estimates of upper mantle olivine content can be obtained fromP-wave,S-wave, and bulk sound velocity contrasts at 400 km only if ln /T of has a value of about–2×10–4K–1, yielding approximately 52% olivine by volume. A value of ln /T smaller in magnitude would require reassessment of several underlying assumptions.  相似文献   

13.
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   

14.
Considering the blocking problem as a baroclinic instability problem in a dispersive wave system with diabatic heating effects, it is of great interest to investigate the role of wavegroup velocityv gr in blocking processes, becausev gr controls the energy transfer in the wave field. Using a Newtonian Cooling —type of forcing with a phase differencek to the main field and taking the linearized version of a two-level model, the phase speedc r, the group velocityv gr and the growth ratekc i have been obtained as analytical functions of the mean zonal windU, the thermal windU T, the coefficient of diabatic heating x, the phase differencek and the wavelengthL. Now the hypothesis is introduced, that a blocking should be expected, ifv gr has a maximum value in the vicinity ofL o, for whichc r vanishes and thee-folding timet=1/kc i (kc i>0) is smaller than 6 days (see condition (20) in the text). One finds, that for special parameter combinations (U T, U, ), where 15 m/secU T25m/sec,U=10m/sec, 0.8·10–51.5·10–5 [sec–1], certain valuesL o with an appropriate phase differencek exist, which satisfy the conditions mentioned above (for values see Table 2). TherebyL o varies within the range 8500 km <L o<11000 km corresponding to the preferred planetary blocking wavenumber 2 in middle latitudes 50°<<70° N.  相似文献   

15.
Summary Mean equatorial gravity has been computed from geopotential models GEM-10C, GEM-7, GEM-T1, GEM-T2, GEM-T3, JGM-1, JGM-2, JGM-3 and OSU91A and compared to the normal equatorial gravity, e=978 032·699 × 10–5 m s–2, computed from four given parameters defining the Earth's level ellipsoid. In all models ge>e.  相似文献   

16.
An analysis is made of the long-period geomagnetic pulsations as recorded at seven Norilsk meridian stations ( = 162°, latitudinal range: 61°–71°N) following abrupt magnetospheric expansion during the storm of 22 March 1979 caused by a rapid decrease in solar wind density. As with the time interval following an abrupt contraction at the time of sudden storm commencement, there exist two types of pulsations in the pulsation spectra: latitude-independent (T>400 s) and latitude-dependent (T<200 s) pulsations. The first pulsation type is interpreted in terms of forced pulsations associated with magnetopause oscillations. The oscillation period is determined by plasma density in the boundary layer and by the radius of the magnetosphere (T 1/2R4). The latitudinal dependence of the period, amplitude and polarization of the second-type pulsations is in agreement with the resonance mechanism of their origin.  相似文献   

17.
Summary Auroral spectra taken from within the auroral zone reveal H-emission as not limited to the magnetic zenith but as extending over the sky. The surface brightness forH andH may tentatively be estimated to a few airglows. The assumption is made that some of this emission may extend to the very low gm latitudes and be practically universal and the possible mode of excitation of neutral hydrogen in space is speculated upon. At the earth's orbit the density number of the cosmic, infalling, hydrogen accreted from beyond the solar system towards the sun is about 102 neutral atoms cm–3 and coronal plasma contributions cannot encrease this number by more than a factor of two. If an exceptionally violent solar disturbance ejects stream-electrons attaining velocities-of 2,200 km sec–1 corresponding to the threshold energy forH excitation of 12.8 eV and if these electrons, at the earth's orbit, have a density number of 103 cm–3, then a shell about 100,000 km thick may contributeH emission having a surface brightness of about 0.1 airglow this being the higher probable value. Such anH-emission could be detectable from all latitudes during, or, most probably, just before the occurence of an auroral storm.  相似文献   

18.
A unified model is proposed for explaining the frequency dependent amplitude attenuation and the coda wave excitation on the basis of the single scattering process in the randomly inhomogeneous lithosphere. Adopting Birch's law and a direct proportion between density and wave velocity, we statistically describe the inhomogeneous medium by one random function characterized by the von Karman autocorrelation function. We calculate the amplitude attenuation from the solid angle integral of scattered wave energy on the basis of the Born approxiimation after subtracting the travel-time fluctuation effect caused by slowly varying velocity inhomogeneities. This subtraction is equivalent to neglect energy loss by scattering within a cone around the forward direction. The random inhomogeneity of the von Karman autocorrelation function of order 0.35 with the mean square fractional fluctuation of 7.2×10–3 1.3×10–2 and the correlation distance of 2.15.1 km well explains observed backward scattering coefficientg and the ratioQ P –1 /Q S –1 , and observed and partially conjecturedQ S –1 for frequencies between 0.5 Hz and 30 Hz.  相似文献   

19.
Zusammenfassung Es werden die Grundgleichungen der Ionisations-Neutralisationsbilanz in derE-Schicht präzisiert und auf die Notwendigkeit der Berücksichtigung des Einflusses der lokalen ionisierenden Strahlungsquellen auf der Sonnenscheibe, der dynamischen ionosphärischen Vorgängen und der Veränderungen des äquivalenten Rekombinationskoeffizienten hingewiesen. Ferner wird eine Methodik zur Bestimmung der charakteristischen Grössen der Ionisations-Rekombinationsbilanz (q 0m ,q d, ) dargelegt. Zu dem Zweck werden die Messergebnisse aus der Periode der Sonnenfinsternis von zwei unweit voneinander gelegenen Ionosphärenstationen verwendet. Die Methodik wird auf die während der totalen Sonnenfinsternis am 15. Februar 1961 auf den Ionosphärenstationen in Sofia und Nesebar erhaltenen Ergebnisse angewandt. Für den Rekombinationskoeffizienten werden Werte zwischen 0,63·10–7 cm3sec–1 und 2,32·10–7 cm3sec–1 und für die Elektronenproduktion unter dem Einfluss der ionisierenden Strahlung von der homogenen Sonnenscheibeq 0m 1700 cm–3sec–1 erhalten.
Summary The basic equations for the ionisation-neutralisation balance in theE layer have been shown the necessity to take in account the influence of the local ionisation sources on the disk of the sun, the dynamic ionospheric processes and the variations in the equivalent recombination coefficient. The method for determining the characteristic quantities of the ionisation-recombination balance (q 0m ,q d, ) has been exhibited for this purpose are used measurement data from two ionospheric stations located not far from each other, in the period of the solar eclips on 15 February, 1961. The quantity of the recombination coefficient lay between 0.63×10–7 sec–1 cm3 and 2.32×10–7 sec–1 cm3; the electron production under the action of the ionising radiation of the homogen disk showsq 0m 1700 sec–1 cm–3.
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20.
The time clustering of earthquakes occurring in the Hellenic arc-trench system is quantitatively analyzed by means of the fractal dimension,D, of their time distribution in the time intervals of 1950–1985 (M s >-4.5) and 1964–1985 (M s 4.0). The results obtained imply that scale-invariant clustering holds over very large scale lengths of time,T, with 22–28T (in min) 220–222, depending on the seismotectonic segment considered. In all segments a common feature is the relation between theD 1,D 2 andD 3-values found for shallow, intermediate-depth and all-depth shocks, respectively:D 3>D1>D2. TheD-values found for shallow shocks range between 0.137 and 0.191 with the exception of the Ionian Islands and Cretan segments where anomalously high values (D=0.221–0.251) have been determined. We discuss possible seismotectonic interpretations of the results.  相似文献   

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