What should be observed on the sun     

Z. Švestka 《Solar physics》1976,47(1):375-384

Three problems are emphasized in particular: the preflare magnetic field configuration, velocity fields, and the nature of acceleration processes in flares. It is concluded that what we need most urgently are high-resolution hard X-ray, soft X-ray, and EUV-pictures, coronal spectra, and magnetograms with high resolution both in space and time. A space-shuttle equipped with instrumentation of this kind would contribute significantly to our knowledge of the flare process.  相似文献   

Changes of the profiles of spectral lines due to mass transfer in close binaries     

Zdislav Šíma 《Astrophysics and Space Science》1973,24(2):421-448

In this paper, the model of the ring envelope round the primary component and the stream of the gaseous mass flowing from the secondary component to the primary is constructed on the basis of theoretical computations concerning the exchange of the mass between the components of the binary. The paper studies the influence of the gaseous mass on the profiles of spectral lines before and after occultation; the influence of the stream on the profile in case the secondary is near elongation, is also investigated. The line profiles obtained by numerical computations show that their changes caused by outflowing mass should be well detectable from spectrograms taken at particular phase of the binary. Changes in the lines may influence the measurement of radial velocities. The method for distinguishing the influence of the stream from the influence of the ring is described.  相似文献   

A comment on the flare activity in August 1972     

L. Fritzová-Švestková  Z. Švestka} 《Solar physics》1973,29(2):417-419

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On the Integrability of Limited-Area Numerical Weather Prediction Model ALADIN over Extended Time Periods     

Huth  Radan  Mládek  Richard  Metelka  Ladislav  Sedlák  Pavel  Huthová  Zuzana  Kliegrová  Stanislava  Kyselý  Jan  Pokorná  Lucie  Halenka  Tomáš  Janoušek  Martin 《Studia Geophysica et Geodaetica》2003,47(4):863-873

This note summarizes results of the first integration of regional numerical weather prediction model ALADIN in a climate mode. The ALADIN model, developed in an international cooperation led by Météo France, is operationally used for weather prediction. The grid step of the model is 12 km; the integration domain covers a major part of Europe. A one-month-long run has been performed with this model on observed boundary conditions (represented by assimilations by the global model ARPEGE). It is demonstrated that no excessive error is generated and accumulated in the model during the integration; hence the model is integrable for extended time periods and may serve a basis for a development towards a regional climate model.  相似文献   

Seismic Activity Around and Under Krakatau Volcano,Sunda Arc: Constraints to the Source Region of Island Arc Volcanics     

Špičák  A.  Hanuš  V.  Vaněk  J. 《Studia Geophysica et Geodaetica》2002,46(3):545-565

There is general agreement that calc-alkaline volcanic rocks at convergent plate margins are genetically related to the process of subduction (Ringwood, 1974; Maaloe and Petersen, 1981; Hawkesworth et al., 1997). However, opinions on the mode and site of generation of primary magma for island arc volcanism differ substantially. The site of generation of calc-alkaline magma is thought to be either in the mantle wedge (Plank and Langmuir, 1988; McCulloch and Gamble, 1991) or in the subducting slab (White and Dupré, 1986; Defant and Drummond, 1990; Edwards et al., 1993; Ryan and Langmuir, 1993). We present seismological evidence in favour of the latter concept. A distinctive seismicity pattern around and under the Krakatau volcano was identified during systematic studies of the SE Asian convergent plate margins by means of global seismological data. A column-like cluster of events, probably associated with the dynamics of the volcano, is clearly separated from the events in the Wadati-Benioff zone. The accuracy of hypocentral determinations of the events of the cluster does not differ from the accuracy of the events belonging to the subducting slab. The depths of the cluster events vary from very shallow to about 100 km without any apparent discontinuity. On the other hand, there is a pronounced aseismic gap in the Wadati-Benioff zone directly beneath the volcano at depths between 100-150 km. The Krakatau cluster connects this aseismic gap to the volcano at the surface. The pervasive occurrence of earthquakes in the continental wedge between the subducting slab and the Earth surface bears witness to the brittle character of the continental lithosphere and casts doubt on the existence of large-scale melting of mantle material. The aseismic gap (Hanu and Vank, 1985), interpreted by us as a partially melted domain occurring in subducted slabs in practically all active subduction zones that reach depths greater than 100 km, is here used as evidence for the location of the primary source region of island arc volcanics in the subducting plate.  相似文献   

A comparative study of geothermal and meteorological records of climate change in Kamchatka     

V. Čermák  J. Šafanda  L. Bodri  M. Yamano  E. Gordeev 《Studia Geophysica et Geodaetica》2006,50(4):675-695

To reconstruct the recent climate history in Kamchatka, a series of repeated precise temperature logs were performed in a number of boreholes located in a broad east-west strip (between 52 and 54°N) in the central part of Kamchatka west of Petropavlovsk-Kamchatski. Within three years more than 30 temperature logs were performed in 10 holes (one up to six logs per hole) to the depth of up to 400 metres. Measured temperature gradients varied in a broad interval 0 to 60 mK/m and in some holes a sizeable variation in the subsurface temperatures due to advective heat transport by underground water was observed. Measured data were compared with older temperature profiles obtained in the early eighties by Sugrobov and Yanovsky (1993). Even when older data are of poorer precision (accuracy of about 0.1 K), they presented valuable information of the subsurface temperature conditions existing 20–25 years ago. Borehole observations and the inverted ground surface temperature histories (GSTHs) used for the paleoclimate reconstruction were complemented with a detailed survey of meteorological data. Namely, the long-term surface air temperature (SAT) and precipitation records from Petropavlovsk station (in operation since 1890) were used together with similar data from a number of local subsidiary meteo-stations operating in Central Kamchatka since 1950. Regardless of extreme complexity of the local meteorological/climate conditions, diversity of borehole sites and calibration of measuring devices used during the whole campaign, the results of the climate reconstruction supported a general warming of about 1 K characteristic for the 20th century, which followed an inexpressive cooler period typical for the most of the 19th century. In the last three to four decades the warming rate has been locally increasing up to 0.02 K/year. It was also shown that the snow cover played a dominant role in the penetration of the climate “signal” to depth and could considerably smooth down the subsurface response to the changes occurred on the surface.  相似文献   

Seismic Moment Tensor Resolution on a Local Scale: Simulated Rockburst and Mine-induced Seismic Events in the Kopanang Gold Mine, South Africa   总被引：2，自引：0，他引：2  

Jan Šílený  Alexander Milev 《Pure and Applied Geophysics》2006,163(8):1495-1513

Seismic records contain information about the effect of the source as well as the effect of wave propagation through the rock mass. The effect of wave propagation is usually not well known as only simplified models of geological structures are available. Therefore, the information about the source retrieved by inverting seismograms may include errors due to incomplete knowledge of the rock mass along the propagation path, which in turn cause a distortion in the calculated moment tensor (MT). The distortion of the MT on a local scale was observed by inverting records of a simulated rockburst conducted at the Kopanang gold mine in South Africa. A dominant isotropic component of the explosive characteristics was found from the inversion. The deviatoric components retrieved from the blast are spurious. A test of their stability indicated that they are not significant, assuming an uncertainty above 5% for velocities and 10% for attenuation within the homogeneous model available for the mine. Thus, the retrieval of the MT from records of local networks in mines using a homogeneous model of the rock mass seems to be feasible. However, the homogeneous model of the rock mass can only be applied to close stations, within a few kilometers of the source. The seismic records from distant stations were too complex to be modelled by a homogeneous rock mass. Records of six mine-induced seismic events recorded at the Kopanang gold mine were also inverted. A vertical linear dipole along the pressure (P) axis was found for three of the events, suggesting a pillar burst. The mechanism of two events contains an isotropic implosion together with a nearly vertical dip-slip, and seems to indicate a combination of a cavity collapse with a down dip-slip along a nearly vertical fault. One event corresponds to a dipole along the tensional (T) axis. However, it is vertical, thus its association with tensile faulting of the hangingwall is uncertain.  相似文献   

Comparison of three mathematical models for the estimation of 10-day drain discharge     

K. Pandžić  I. Šimunić  F. Tomić  S. Husnjak  T. Likso  D. Petošić 《Theoretical and Applied Climatology》2006,85(1-2):107-115

Summary This paper presents an the evaluation of three mathematical models for the estimation of 10-day drain discharge using weather, pedological and phenological parameters. One model uses modified Palmer’s procedure for the calculation of water balance components and the second two use empirical multiple linear regression. The models have been applied to data of an amelioration experimental field in central Croatia (south-western part of the Pannonian Lowland), where a set of average 10-day air temperature and relative humidity data, average wind speed, cumulative precipitation and drain discharge amounts, insolation and soil moisture data and vegetation indices have been collected. The experiment has been performed during the period 1990–1992. The models have been tested by comparing estimated and observed 10-day drain discharge amounts. All models mainly give acceptable cumulative results although their accuracy depends on the season.  相似文献   

Prolonged Dry Episodes over North America: New Tendencies Emerging During the Last 40 Years     

Pavel Ya. Groisman Richard W. Knight 《地球科学进展》2007,22(11):1191-1207

A disproportionate increase in precipitation coming from intense rain events, in the situation of general warming (thus, an extension of the vegetation period with intensive transpiration) and an insignificant change in total precipitation could lead to an increase in the frequency of potentially serious type of extreme events: prolonged periods without precipitation (even when the mean seasonal rainfall totals increase). This paper investigates whether this development is already occurring during the past several decades over North America south of 55°N, for the same period when changes in frequency of intense precipitation events are being observed. Lengthy strings of “dry” days without sizeable (>1.0 mm) precipitation were assessed only during the warm season (defined as a period when mean daily temperature is above the 5℃ threshold) when water is intensively used for transpiration and prolonged periods without sizable rainfall represent a hazard for terrestrial ecosystem's health and agriculture. During the past four decades, the mean duration of prolonged dry episodes (20 days or longer in southeastern Canada, 1 month or longer in the Eastern United States and along the Gulf Coast of Mexico and 2 months or longer in the Southwestern United States and Northern Mexico) has significantly increased. As a consequence, the return period of 1 month long dry episodes over the Eastern U.S. has been reduced more than twofold from 15 to 6~7 years. The longer average duration of dry episodes has occurred during a relatively wet period around most of the continent south of 55°N but is not observed over the Northwestern U.S. and adjacent regions of Southern Canada.   相似文献   

2006年国家自然科学基金批准项目一览表(地球科学部分)     

Pavel Ya. Groisman  Richard W. Knight 《地球科学进展》2007,22(1):82-110

~~2006年国家自然科学基金批准项目一览表(地球科学部分)~~  相似文献