The Granadilla pumice deposit of Southern Tenerife,Canary Islands     

Basil Booth 《Proceedings of the Geologists' Association. Geologists' Association》1973,84(3):353-IN5

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The motion of a satellite in a ring potential     

Basil Zafiropoulos 《Astrophysics and Space Science》1987,139(2):353-364

This investigation presents the orbital elements of a satellite moving in a circular ring potential. The ring is considered to be of infinitesimal thickness and of unit radius. The components of the perturbing accelerations due to the ring potential have been substituded into the Gauss form of Lagrange's planetary equations to yield the first-order approximations. The elements of the orbit have been expressed by means of Hansen coefficients. The results include the effects produced by the 2nd, 4th, 6th, and 8th spherical harmonics. Due to their importance we present separately the secular terms from the periodic ones. The general expressions for the orbital elements can be easily extended to include the effects produced by any other higher harmonic.List of Symbols semi-major axis - C _jK ⁿ (u, ) cosine functions ofu and - e eccentricity of the orbit - f sin² - inclination of the orbit - M mean anomaly - n mean motion - p semi-latus rectum of the orbit - R, S, andW components of the perturbing acceleration - r magnitude of position vector - S _jK ⁿ (u, ) sine functions ofu and - T time of periapse passage - u argument of latitude - U gravitational potential - V perturbing potential - G(M _r +m) (gravitational constant times the sum of the masses of ring and satellite) - _{n, k} coefficients ofR component of disturbing acceleration (functions off) - _{n, k} coefficients ofS andW components of disturbing acceleration (functions off) - mean anomaly at timet=0 - X ₀ ^{n, m} zero-order Hansen coefficients - argument of periapse - longitude of the ascending node  相似文献   

Determination of noise spectra from strong motion data recorded in Greece   总被引：1，自引：0，他引：1  

A.A. Skarlatoudis  C.B. Papazachos  B.N. Margaris 《Journal of Seismology》2003,7(4):533-540

A large number of strong ground motions inGreece have been recorded by analogaccelerographs. The processing of analogstrong motion recordings and conversion toa digital form introduces noise in thesignal, due to the digitization andprocessing whichsignificantly affects the record. In thepresent paper a unified processing anddetermination of digitization andprocessing noise for the Greek strongmotion records is presented. Moreover,appropriate relations are proposed for thelower cut-off frequency with respect tothe epicentral distance and earthquakemagnitude for record filtering.  相似文献   

The advantage of determination of earthquake magnitudes in Greece in the local scale     

B.C. Papazachos  V.G. Karakostas  A.A. Kiratzi  B.N. Margaris  C.B. Papazachos  E.M. Scordilis 《Journal of Seismology》2002,6(4):589-591

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A unified approach to orbital,solar, and lunar forcing based on the Earth’s latitudinal insolation/temperature gradient     

Basil A.S. Davis  Simon Brewer 《Quaternary Science Reviews》2011,30(15-16):1861-1874

Widespread empirical evidence suggests that extraterrestrial forcing influences the Earth’s climate, but how this could occur remains unclear. Here we describe a new approach to this problem that unifies orbital, solar and lunar forcing based on their common control of the Earth’s latitudinal insolation gradient (LIG). The LIG influences the climate system through differential solar heating between the tropics and the poles that gives rise to the latitudinal temperature gradient (LTG), which drives the Earth’s atmospheric and (wind driven) ocean circulation. We use spectral analysis of recent changes in the Earth’s LTG to support earlier work on orbital timescales (Davis and Brewer, 2009) that suggests the climate system may be unusually sensitive to changes in the LIG. Identification of LIG forcing of the LTG is possible because the LIG varies according to seasonally specific periodicities based on obliquity in summer (41 kyr orbital and 18.6 yr lunar cycle), and precession (21 kyr orbital cycle) and total solar irradiance (11 yr solar cycle) in winter. We analyse changes in the Northern Hemisphere LTG over the last 120 years and find significant (99%) peaks in spectral frequencies corresponding to 11 years in winter and 18.6 years in summer, consistent with LIG forcing. The cross-seasonal and multi-frequency nature of the LIG signal, and the diffuse effect of the LTG driver on the climate system may account for the complexity of the response to extraterrestrial forcing as seen throughout the climatic record. This hypersensitivity of the LTG to the LIG appears poorly reproduced in climate models, but would be consistent with the controversial theory that the LTG is finely balanced to maximise entropy.  相似文献   

Uncertainties in the estimation of earthquake magnitudes in Greece   总被引：1，自引：0，他引：1  

B.C. Papazachos  V.G. Karakostas  A.A. Kiratzi  B.N. Margaris  C.B. Papazachos  E.M. Scordilis 《Journal of Seismology》2002,6(4):557-570

Instrumental magnitudes in Greece have been reported as: a) Mmagnitudes based on the records of the Wiechert or Mainka seismographs,b) M_LGR magnitudes based on the records of the Wood-Anderson(WA) seismographs (T_o = 0.8 sec, V_effective 1000) or othershort period seismographs calibrated against WA records and,c) M_LSM magnitudes based on strong motion records(accelerograms). Comparison of such magnitudes with momentmagnitudes, M_w, for 329 earthquakes, with epicenters in thebroader Aegean area, performed in this study, showedthat M, M_LGR+0.5 and M_LSM are practically equalto M_w, with a small overall standard error ( = 0.23).Therefore, equivalent moment magnitudes, M_w ^*,estimated from these magnitudes and reported in the catalogues of theGeophysical Laboratory of the University of Thessaloniki are equal tomoment magnitudes for all practical purposes with reasonable uncertainties.It has been further shown that surface wave magnitudes, M_s,for M_s <6.0, can be also transferred into momentmagnitudes, M_w ^*, but the larger uncertaintiesencountered make its use rather problematic.  相似文献   

The distribution of solar flares for the time period 1967–1985     

Basil Petropoulos  C. Poulakos 《Earth, Moon, and Planets》1989,46(2):107-125

The distribution of monthly counts of grouped solar flares N _f has been studied for the time period 1967–1985 and they have been compared to other solar activity index R _z , F ₂₈₀₀, and F ₃₇₅₀ i.e. intensities of solar radio flux at 2800 MH _z and 3750 MH _z . Seasonal variations have been found in the monthly distribution of solar flares.We have also studied the variation of the correlation coefficient for every year between N _F and R _z for the time period 1967–1985. The distribution of monthly counts of grouped solar flares N _f has also been compared to the number at high velocity solar-wind streamers for the same period.  相似文献   

Physical parameters of the martian atmosphere     

Basil Petropoulos  Constantin Macris 《Earth, Moon, and Planets》1989,46(1):1-30

The following physical parameters have been computed from 0 to 200 km altitude; (1) pressure, (2) density (3), speed of sound, (4) density, (5) number density, (6) mean free path, (7) viscosity, (8) pressure scale, (9) mean particle velocity, (10) collisional frequency and (11) columnar mass.The Viking measurements have been used as input data. A critical comparison of the computed pressures and densities, is given, useful for future explorations.  相似文献   

Groundwater overdraft vulnerability and environmental impact assessment in Arusha   总被引：3，自引：0，他引：3  

Basil T. I. Ong’or  Shu Long-cang 《Environmental Geology》2007,51(7):1171-1176

A simple approach is proposed for identifying areas vulnerable to groundwater overdraft. The methodology utilizes GIS techniques to analyze and evaluate controlling factors in areas with little data. The proposed methodology was applied in Arusha. Water demand in Arusha Municipality and its environs has increased to about 5.3% annually since 1999. Groundwater levels have declined. The aquifer hydrogeological variables were evaluated for impact to potential groundwater overdraft by overlay and index techniques. The spatial distribution of overdraft vulnerability was discussed. The northwestern part of Arusha is the most vulnerable to overdraft and possible serious environmental impacts. The Loruvani area has the most potential for aquifer development due to its permeability, high recharge rate, massive aquifer thickness and low drawdown.  相似文献   

Northward migration under a changing climate: a case study of blackgum (Nyssa sylvatica)     

Johanna Desprez  Basil V. Iannone III  Peilin Yang  Christopher M. Oswalt  Songlin Fei 《Climatic change》2014,126(1-2):151-162

Species are predicted to shift their distribution ranges in response to climate change. Region-wide, empirically-based studies, however, are still limited to support these predictions. We used a model tree species, blackgum (Nyssa sylvatica), to study climate-induced range shift. Data collected from two separate sampling periods (1980s and 2007) by the USDA’s Forestry and Inventory Analysis (FIA) Program were used to investigate changes in abundance and dominance, and shifts in distribution, of blackgum in four ecoregions of the eastern United States. Our results indicated new recruitment of blackgum in the northern portion of its range, along with increases in both density and annual rates of change in importance value (IV). Conversely, declines in recruitment were found in the southern portion of blackgum’s range, along with decreases in density and IV. The center portion of blackgum’s range had mixed patterns of change (i.e., both increases and decreases) throughout. A northward range expansion was also detected by comparing blackgum’s historic range to where it was detected during our two more-recent sampling periods. Our findings suggest that blackgum is migrating north in response to climate change. Our study also suggests two broader implications about tree migration patterns in response to climate change: (1) species can respond to changing climate in relatively short time periods, at least for generalist species such as blackgum, and (2) climate-induced vegetation dynamic patterns can be detected at the regional level, but are inherently complex.  相似文献