An Overview of the MATERHORN Fog Project: Observations and Predictability     

I. Gultepe  H. J. S. Fernando  E. R. Pardyjak  S. W. Hoch  Z. Silver  E. Creegan  L. S. Leo  Zhaoxia Pu  S. F. J. De Wekker  Chaoxun Hang 《Pure and Applied Geophysics》2016,173(9):2983-3010

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The first electric field pulse of cloud and cloud-to-ground lightning discharges     

Noor Azlinda Ahmad  M. Fernando  Z.A. Baharudin  M. Rahman  V. Cooray  Ziad Saleh  Joseph R. Dwyer  Hamid K. Rassoul 《Journal of Atmospheric and Solar》2010,72(2-3):143-150

In this study, the first electric field pulse of cloud and cloud-to-ground discharges were analyzed and compared with other pulses of cloud discharges. Thirty eight cloud discharges and 101 cloud-to-ground discharges have been studied in this analysis. Pulses in cloud discharges were classified as ‘small’, ‘medium’ and ‘large’, depending upon the value of their relative amplitude with respect to that of the average amplitude of the five largest pulses in the flash. We found that parameters, such as pulse duration, rise time, zero crossing time and full-width at half-maximum (FWHMs) of the first pulse of cloud and cloud-to-ground discharges are similar to small pulses that appear in the later stage of cloud discharges. Hence, we suggest that the mechanism of the first pulse of cloud and cloud-to-ground discharges and the mechanism of pulses at the later stage of cloud discharges could be the same.  相似文献   

A Study of the Solar-Like Properties of β Hydri     

Maria Pia Di Mauro  Jørgen Christensen-Dalsgaard  Lucio Paternò 《Astrophysics and Space Science》2003,284(1):229-232

We investigate properties of the internal structure of HR2021, better known as Hydri, a G2 IV subgiant with mass close to solar and for which observations by Bedding et al. (2001) have shown the presence of solar-like oscillations.We have computed models of Hydri,based on updated global parameters,and compared the computed frequencies for the models with the observed oscillation spectrum.  相似文献   

The role of the exchanges through the Strait of Gibraltar on the budget of elements in the Western Mediterranean Sea: consequences of human-induced modifications     

Gómez F 《Marine pollution bulletin》2003,46(6):685-694

The role of the Strait of Gibraltar on the exchanges of substances between Mediterranean Sea and the Atlantic Ocean is reviewed. The previous estimations have been recalculated by using a similar water flux and compared with the river and atmospheric inputs to the Western Mediterranean Sea. The man-induced changes in the dimensions of the Strait of Gibraltar increasing (planning the sill) or reducing of the cross-section by a total or partial dam are discussed. A total dam will control the sea-level rise in the Mediterranean Sea, but an annual increase of major nutrient concentrations of 1-2% could be expected, lower than the rate of increase of the river and atmospheric inputs in the Western Mediterranean Sea. The increase of the cross-section of the Strait by increasing the depth (planning) at the sill could compensate the increase of the external nutrient inputs.  相似文献   

Shear-induced folding in Arsia Mons aureole: Evidence for low-latitude martian glaciations     

Francisco Anguita  Fernando Moreno 《Earth, Moon, and Planets》1992,59(1):11-22

Folds up to 50 km across have been identified on Arsia Mons aureole. Tharsis Province, Mars. The structures, located on Mars for the first time, are close to Aganippe Fossa and other huge faults which have behaved as left-lateral shear zones and then as extensional features. A tectonic scheme is proposed to explain the folds as shear-induced structures. Folding reveals a layered sequence in the aureole, and that is taken as a definitive evidence for its deposition by ice.If at least some of the Tharsis volcanoes aureoles are basal moraines, their study is critical, as they could contain a record of Mars paleoclimatic fluctuations. Martian past frozen lakes or oceans have been proposed, and some sediments found on the northern plains could have been deposited on the bottom of those basins. If this is so, those formations should be layered sequences and could also bear the traces of tectonic stresses, detectable as folds on Viking imagery. Correlation of these two kinds of evidence seems a promising line to tackle the Martian paleoclimatic problem.  相似文献   

Tornadoes in Southern Apulia (Italy)     

F.?GianfredaEmail author  M.?M.?Miglietta  P.?Sansò 《Natural Hazards》2005,34(1):71-89

Numerous tornadoes have traversed southern Apulia in the course of the last five centuries, causing severe damage and a significant loss of life. Historical chronicles and newspaper articles allowed more than 30 tornadic events to be identified; in particular, 26 of these have occurred during the last two centuries. In all, 24 small towns and villages of southern Apulia suffered on at least one occasion the disastrous effects of being hit by a tornado.Collated data reveals that tornadoes generally form from May to December, with the most powerful events taking place in the month of September, followed by October and November. Tornadoes generally cluster in the southernmost area of the region and typically follow a path leading from the south-west to the north-east. Path length were observed to vary from 8 to 73km, and widths ranging from 60 to 850m.The metereological analysis carried out for the events occurred after 1950, even if based on a limited data set, reveals a few typical meteorological scenarios associated with the development of tornadoes over Salento.In southern Apulia tornadoes can be classified from levels A2 to A4 in accordance with the Damage Area Scale.  相似文献   

Fluidization of sediments in a conical basin by subterranean springs: relevance to Lake Banyoles     

Xavier Casamitjana  Jordi Colomer  Harindra J. S. Fernando 《Aquatic Sciences - Research Across Boundaries》2000,62(1):79-90

: An experimental study was carried out to investigate the resuspension of particles by a momentum jet discharging from below into a conical basin. The work was motivated by its relevance to Lake Banyoles, where sediments are suspended in different conical basins by bottom jets fed by a groundwater karstic system. Two different flow regimes were identified: a "Jet Flow" regime (JF) and a "Lutocline Flow" regime (LF). In the LF regime, the particles were resuspended, forming a well-established interface along the entire cross-sectional ara of the cone. This regime occurs when the particle Reynolds number Re_p = (u-w_s)d_p/ n {\bf Re_p = (u-w_s)d_p/ \nu} where u is the mean velocity of the flow at the jet entry, ws is the settling velocity of particles, dp is the diameter of that particles and n {\bf \nu} is the kinematic viscosity of water) is below a critical number Rec that depends on the slope of the basin. The maximum height to which particles rise in the LF regime was also determined as a function of four non-dimensional variables: D1 = ho/(Mo^1/2/ws), D2 = ho/dp, Rep and tan  b {\bf tan \, \beta} (where ho is the height of the particle bed, Mo is the kinematic momentum flux of the jet and tan  b {\bf tan \, \beta} is the slope of the basin). Application of the results to the basins of Lake Banyoles showed a good agreement provided that the aggregate properties of the suspensions are used. It is also shown that, in the LF regime, inflows to the basins can be estimated by a simple technique based on a balance between the sedimentation flux and the upward advection of sediments by the mean flow.  相似文献   

Light curve and orbital elements of V 337 Aquilae     

F. A. Catalano  S. Catalano  M. Rodonò 《Astrophysics and Space Science》1971,11(2):232-243

From photoelectric observations of V 337 Aql a new solution is carried out. Transit at primary eclipse in disagreement with the Wright-Dugan results is found. Both Russell-Merrill and Kitamura methods of light curve solution are used. The slight period variation and the distortions of the light curve would support the idea that a mass exchange could be in act.  相似文献   

Convection in a rotating deep compressible spherical shell: Application to the Sun     

Gaetano Belvedere  Lucio Paternò 《Solar physics》1977,54(2):289-312

In this paper we study the interaction of rotation with convection in a deep compressible spherical shell as the Sun's convection zone. We examine how the energy transport and the large scale motions can be affected by rotation. In particular we study how a large scale meridional circulation can give rise to variations of angular velocity with latitude and depth.It is assumed that the energy transport is only due to convection and that the mixing-length theory gives an adequate representation of it. Furthermore we assume that rotation acts as a perturbation of the turbulent convective flux through its transport coefficient.The equations involved in the model are integrated numerically in the limit of large viscosity and slow rotation. After having expanded all physical quantities to the first order in terms of Legendre polynomials, the fitting with the observed solar differential rotation gives the expansion parameter, which represents the coupling constant between rotation and convection.The results show a three-cell circulation extending from the poles to the equator. The first one is located in the lower half of the convection zone with the fluid rising at the equator and sinking at the poles. In the second one the direction of the motion is reversed while the third one, located in a thin upper layer, shows the same characteristics of the first one. The meridional velocities at the surface are directed towards the poles and are about 20 cm s^-1. In the other cells the meridional velocities are typically of a few cm s^-1 while the radial velocities are of the order of a few tenths of cm s^-1.The heat flux relative variation at the surface is about 10^-4 (3 × 10^-3 at the bottom) with a polar excess. The temperature variation at the surface is of the same order, with an equatorial excess however. The convection seems to be stabilized stronger at the equator. The angular velocity increases inwards and varies about 6% between the surface and the bottom of the convection zone.An attempt is made for explaining the picture which emerges. In particular the negligible flux and temperature variations at the surface are explained in terms of equalization by the particular structure of the latitudinal flow. This configuration of large scale circulation is attributed to the high stratification of the convection zone with depth.  相似文献   

Surface Reynolds stresses determined from the analysis of facular motions and the maintenance of the Sun's differential rotation     

G. Belvedere  G. Godoli  S. Motta  L. Paternò  R. A. Zappalà 《Solar physics》1976,46(1):23-28

From the analysis of the motions of faculae for a four year period from 1967 to 1970, the latitudinal angular momentum transport by Reynolds stresses at the Sun's surface is calculated. The result agrees fairly well with the one obtained by Ward analyzing spot motions. A comparison with theory suggests that the Sun's differential rotation could be maintained only by Reynolds stresses at the surface. The implications of this result are discussed.  相似文献