Lake Balkhash,Kazakhstan   总被引：2，自引：0，他引：2  

T. Petr 《International Journal of Salt Lake Research》1992,1(1):21-46

Lake Balkhash is a large (18,000 km³), closed, and slightly saline lake in the south-west of Kazakhstan. It is divided into two basins, a south-western and an eastern basin. These have somewhat different limnological conditions, but the most obvious one is that the south-western basin has a salinity of <2 g L⁻¹ whereas the salinity of the eastern basin is ∼4 g L⁻¹. Numerous fish and invertebrate introductions, many successful, have been made. In 1969, a dam impounding the Kapchagay reservoir was constructed on the River Ili, the major river flowing into the lake. The impoundment of water in this reservoir caused a fall of some 1.5 m in the water-level of the lake. This fall, together with other events on the catchment, caused considerable damage to reedswamps in the lake, to the fishery and to conservation values. A number of suggestions has been made on how to prevent further damage. Some, particularly those involving a moratorium on further filling of Kapchagay reservoir and irrigation, have been implemented, at least in part. This has caused some remission in environmental damage and provides for cautious optimism with regard to the lake’s future. Even so, the environmental status of the lake remains vulnerable and many dangers persist.  相似文献   

Book review     

S. J. Gibowicz  Jeremy Bloxham  Petr Vaniček  Gerardo G. Tango  Gerardo G. Tango  Lev Truskinovsky  Konrad Bajer  Krzysztof Haman 《Pure and Applied Geophysics》1991,135(3):493-512

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Post-flare loops of 26 June 1992     

B. Schmieder  P. Heinzel  L. Van Driel-Gesztelyi  J. R. Lemen 《Solar physics》1996,165(2):303-328

We observed the large post-flare loop system, which developed after the X 3.9 flare of 25 June 1992 at 2011 UT, in H with the Multichannel Subtractive Double Pass Spectrograph at Pic-du-Midi and in X-rays with the it Yohkoh/SXT instrument. Following the long-term development of cool and hot plasmas, we have determined the emission measure of the cool plasma and, for the first time, the temporal evolution of the hot-loop emission measure and temperature during the entire gradual phase. Thus, it was possible to infer the temporal variation of electron densities, leading to estimates of cooling times. A gradual decrease of the hot-loop emission measure was observed, from 4 × 10³⁰ cm^–5 at 2300 UT on 25 June 1992 to 3 × 10²⁸ cm^–5 at 1310 UT on 26 June 1992. During the same period, the temperature decreased only slowly from 7.2 to 6.0 × 10⁶ K. Using recent results of NLTE modeling of prominence-like plasmas, we also derive the emission measure of cool H loops and discuss their temperature and ionisation degree. During two hours of H observations (11–13 hours after the flare) the averaged emission measure does not show any significant change, though the amount of visible cool material decreases and the volume of the loops increases. The emission measure in H, after correction for the Doppler-brightening effect, is slightly lower than in soft X-rays. Since the hot plasma seems to be more spatially extended, we arrive at electron densities in the range n _infe ^supho n _infe ^supcool 2 × 10¹⁰ cm^–3 at the time of the H observations.These results are consistent with the post-flare loop model proposed by Forbes, Malherbe, and Priest (1989). The observed slow decrease of the emission measure could be due to an increase of the volume of the loops and a gradual decrease of the chromospheric ablation driven by the reconnection, which seems to remain effective continuously for more than 16 hours. The cooling time for hot loops to cool down to 10⁴ K and to appear in H would be only a few minutes at the beginning of the gradual phase but could be as long as 2 hours at the end, several hours later.  相似文献   

A complex diagnostic of solar prominences     

P. Heinzel  V. Bommier  J. C. Vial 《Solar physics》1996,164(1-2):211-222

We use the polarimetric and intensity measurements of H and HeI D₃ lines in solar prominences to derive the true geometrical thickness for several quiescent prominences. The electron densities, derived from the collisional depolarization in H by Bommier et al. (1994), are used to evaluate the thickness from the emission measure. The emission measure was obtained from the theoretical correlation with the H integrated intensity, according to Gouttebroze, Heinzel, and Vial (1993). Theoretical electron densities obtained by latter authors are also compared with those of Bommier et al. (1994) and we find a very good agreement between them. The prominence geometrical thickness exhibits a relatively large range of values from about 100 km up to a few 10⁴ km. The plasma densities vary by almost two orders of magnitude in the observed structures, but the total column mass in the direction perpendicular to the prominence sheet seems to be fairly constant for the set of prominences studied.  相似文献   

FORMATION OF Ca II LINES IN SOLAR PROMINENCES     

Gouttebroze  P.  Vial  J.-C.  Heinzel  P. 《Solar physics》1997,172(1-2):125-132

We compute the profiles of the resonance lines and infrared triplet of ionized calcium emitted by some representative models of prominences. These models consist of plane-parallel slabs of different temperatures, pressures and thicknesses, standing vertically above the solar surface. These slabs are assumed to be observed at the limb, and to be perpendicular to the line of sight. They are irradiated by the Sun on both sides, and the incoming intensities, at every relevant wavelength, are taken from observations. The model atom includes 3 stages of ionization (Cai, Caii and Caiii) with 5 discrete levels for Caii. We study the relations between emitted intensities and physical properties of the slabs, and compare the intensities emitted in Caii and hydrogen lines for the same set of models. As a result of ionization, the intensity decreases more rapidly with temperature in Caii lines than in Hi lines, so that the ratio of Caii to Hi line intensities may be used as a temperature indicator. The intensity ratio between resonance and infrared lines of Caii depends principally on the optical thickness of the structure. At high pressure and low temperature, the ratio Caii 8542Å/H is found to increase with pressure. This behaviour, which is due to the saturation of H, is opposite to that found by Heasley and Milkey (1978) for low pressures (optically thin structures).  相似文献   

Climate Change in the Urals,Russia, Inferred from Borehole Temperature Data     

Štulc  Petr  Golovanova  Inessa V.  Selezniova  G.V. 《Studia Geophysica et Geodaetica》1997,41(3):225-246

Borehole temperatures in the central and south Urals were analysed for the past ground surface temperature (GST) signal. 31 highquality temperature logs were selected for this purpose and inverted with algorithms based on the generalised least squares theory. The signal to noise ratio was improved by averaging the results of individual borehole inversions. No distinct regional trends were found in the studied region except for some indications of more pronounced warming in the south. The mean GST history (GSTH) was characterised by cooling down to –0.6 °C in the 18th century and subsequent warming to 0.5 °C above the longterm mean at the beginning of this century, and to 1 – 1.5 °C by 1980. The stability of the mean GSTH was tested in dependence on the number of holes used for the averaging. It showed that any subset of 15 holes yielded a GSTH similar to that obtained from the whole set. A surface air temperature (SAT) time series comprising the period 1832 – 1989 was combined from 17 meteorological records. Its least squares warming rate of 1.1 °C per 100 years is somewhat higher than that of the GST (0.7 – 0.8°C/100 years) in the same period.  相似文献   

Wellbore cement degradation in contact zone with formation rock     

Agata Lorek  Małgorzata Labus  Petr Bujok 《Environmental Earth Sciences》2016,75(6):499

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Mg ii Lines Observed During the X-class Flare on 29 March 2014 by the Interface Region Imaging Spectrograph     

W. Liu  P. Heinzel  L. Kleint  J. Kašparová 《Solar physics》2015,290(12):3525-3543

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Preface     

L. Fletcher  P. Heinzel  L. van Driel-Gesztelyi  C. H. Mandrini  F. Fárník 《Solar physics》2015,290(12):3379-3381

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Electron Densities in Quiescent Prominences Derived from Eclipse Observations     

S. Jejčič  P. Heinzel 《Solar physics》2009,254(1):89-100

We develop a diagnostic tool for determination of the electron densities in solar prominences using eclipse data. The method is based on analysis of the hydrogen Balmer-line intensities (namely Hα and Hβ) and the white-light emission due to Thomson scattering on the prominence electrons. Our approach represents a generalization of the ratio method already used by Koutchmy, Lebecq, and Stellmacher (Astron. Astrophys. 119, 261, 1983). In this paper we use an extended grid of non-LTE prominence models of Gouttebroze, Heinzel, and Vial (Astron. Astrophys. Suppl. Ser. 99, 513, 1993) and derive various useful relations between prominence radiation properties and electron densities. Simultaneously, an effective geometrical thickness of the prominence can also be obtained. As an example we apply our general technique to original eclipse data of Koutchmy, Lebecq, and Stellmacher (Astron. Astrophys. 119, 261, 1983). Finally, we use our results to determine the color of prominences as it should be seen during total eclipses.  相似文献