An anomalous subauroral red arc on 4 August, 1972: comparison of ISIS-2 satellite data with numerical calculations     

V. V. Lobzin  A. V. Pavlov  N. M. Pavlova 《Annales Geophysicae》1999,17(11):1411-1425

This study compares the Isis II satellite measurements of the electron density and temperature, the integral airglow intensity and volume emission rate at 630 nm in the SAR arc region, observed at dusk on 4 August, 1972, in the Southern Hemisphere, during the main phase of the geomagnetic storm. The model results were obtained using the time dependent one-dimensional mathematical model of the Earth’s ionosphere and plasmasphere (the IZMIRAN model). The major enhancement to the IZMIRAN model developed in this study to explain the two component 630 nm emission observed is the analytical yield spectrum approach to calculate the fluxes of precipitating electrons and the additional production rates of N⁺₂, O⁺₂, O⁺(⁴S), O⁺(²D), O⁻(²P), and O⁺(²P) ions, and O(¹D) in the SAR arc regions in the Northern and Southern Hemispheres. In order to bring the measured and modelled electron temperatures into agreement, the additional heating electron rate of 1.05 eV cm⁻³ s⁻¹ was added in the energy balance equation of electrons at altitudes above 5000 km during the main phase of the geomagnetic storm. This additional heating electron rate determines the thermally excited 630 nm emission observed. The IZMIRAN model calculates a 630 nm integral intensity above 350 km of 4.1 kR and a total 630 nm integral intensity of 8.1 kR, values which are slightly lower compared to the observed 4.7 kR and 10.6 kR. We conclude that the 630 nm emission observed can be explained considering both the soft energy electron excited component and the thermally excited component. It is found that the inclusion of N₂(v > 0) and O₂(v > 0) in the calculations of the O⁺(⁴S) loss rate improves the agreement between the calculated N_e and the data on 4 August, 1972. The N₂(v > 0) and O₂(v > 0) effects are enough to explain the electron density depression in the SAR arc F-region and above F2 peak altitude. Our calculations show that the increase in the O⁺ + N₂ rate factor due to the vibrationally excited nitrogen produces the 5–19% reductions in the calculated quiet daytime peak density and the 16–24% decrease in NmF2 in the SAR arc region. The increase in the O⁺ + N₂ loss rate due to vibrationally excited O₂ produces the 7–26% decrease in the calculated quiet daytime peak density and the 12–26% decrease in NmF2 in the SAR arc region. We evaluated the role of the electron cooling rates by low-lying electronic excitation of O₂(a¹δ_g) and O₂(b¹σ_g⁺), and rotational excitation of O₂, and found that the effect of these cooling rates on T_e can be considered negligible during the quiet and geomagnetic storm period 3–4 August, 1972. The energy exchange between electron and ion gases, the cooling rate in collisions of O(³P) with thermal electrons with excitation of O(¹D), and the electron cooling rates by vibrational excitation of O₂ and N₂ are the largest cooling rates above 200 km in the SAR arc region on 4 August, 1972. The enhanced IZMIRAN model calculates also number densities of N₂(B³π_g⁺), N₂(C³π_u), and N₂(A³σ_u⁺) at several vibrational levels, O(¹S), and the volume emission rate and integral intensity at 557.7 nm in the region between 120 and 1000 km. We found from the model that the integral integral intensity at 557.7 nm is much less than the integral intensity at 630 nm.  相似文献   

Rhaetian diamond placers in Siberia     

S.A. Grakhanov  Yu.A. Malanin  V.I. Pavlov  V.P. Afanas’ev  N.P. Pokhilenko  A.V. Gerasimchuk  A.N. Lipashova 《Russian Geology and Geophysics》2010,51(1):127-135

Large diamond placers have been discovered in a Rhaetian basal horizon (Upper Triassic) in the north of the Sakha Republic (Yakutia) in the drainage areas of the Eekit, Nikabyt, Kelimyar, and Bur Rivers. In typomorphic features the found diamonds and indicator minerals of kimberlites are completely similar to those from Carnian basal horizons but, in contrast to them, are well sorted, and pyropes show features of mechanical wear. Analysis of the geologic evolution of the study area, morphology of diamonds and indicator minerals, and composition of the latter showed that the Rhaetian productive sediments resulted from the erosion of Carnian placers.  相似文献   

Hydrologo-morphological approach to regionalization of the Selenga river basin     

L. M. Korytny  E. A. Il’icheva  M. V. Pavlov  I. Yu. Amosova 《Geography and Natural Resources》2012,33(3):212-217

We examine the evolutionary stages of scientific views on the formation history of the delta plain of the Selenga river and adjacent territories, based on cartographic material and national investigations spanning the period 1701?C2009. We suggest the regionalization of the Selenga river from hydromorphometric attributes of erosion-accumulation, abrasion-accumulation and neotectonic processes. The study is based on comparing topographic maps, guides for navigation and space images (1898?C2009) as well as on experimental data obtained by the authors.  相似文献   

Superchron at the Mesoproterozoic-Neoproterozoic transition     

V. E. Pavlov  Y. Gallet 《Doklady Earth Sciences》2009,426(1):632-635

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A Newly Determined Paleomagnetic Pole for the Late Ordovician in Siberia and Kinematics of the Siberian Platform on the Time Interval of ~505–455 Ma Ago     

Pavlov  V. E.  Pasenko  A. M.  Dronov  A. V.  Fedyukin  I. V. 《Doklady Earth Sciences》2021,498(2):491-497

Doklady Earth Sciences - A paleomagnetic study of the Chertovskii Horizon of the Moyero River valley was carried out. Based on published and newly obtained data, the sequence of seven reliable...  相似文献   

Accretion-caused deceleration of a gravitationally powerful compact stellar object moving within a dense Fermi gas     

E. P. Tito  V. I. Pavlov 《Astrophysics and Space Science》2016,361(7):209

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Effect that jet streams have on the vertical ozone distribution and characteristics of tropopause inversion layer in the far east region     

O. A. Bukin  Nguen Suan An  A. N. Pavlov  S. Yu. Stolyarchuk  K. A. Shmirko 《Izvestiya Atmospheric and Oceanic Physics》2011,47(5):610-618

The paper describes a lidar and presents the results of lidar sensing of the vertical ozone distribution (VOD); the lidar measurements are analyzed together with data from a network of meteorological stations situated along the 132° E meridian. VODs over Primorye and Japan in the winter period are compared. An analysis showed that an interrelation exists between the subtropical jet stream and the structures of VOD and tropopause inversion layer. Specifically, the region of the VOD local maximum above the tropopause is in the upper part of the tropopause inversion layer and the width of the maximum depends on the distance from the core of the subtropical jet stream. It is found that the local ozone minimum in the lower stratosphere corresponds to the local minimum of the squared Brunt-Vaisala frequency within this same altitude range in the winter season, when two tropopauses frequently overlap. It is conjectured that the local ozone maximum and tropopause inversion layer may be associated with mixing processes in the layer where stratospheric and tropospheric circulation cells come into contact near the core of the subtropical jet stream.  相似文献   

Depositional history of the North Taymyr ice‐marginal zone,Siberia—a landsystem approach     

Helena Alexanderson  Lena Adrielsson  Christian Hjort  Per Mller  Oleg Antonov  Saskia Eriksson  Maksim Pavlov 《第四纪科学杂志》2002,17(4):361-382

The sediment–landform associations of the northern Taymyr Peninsula in Arctic Siberia tell a tale of ice sheets advancing from the Kara Sea shelf and inundating the peninsula, probably three times during the Weichselian. In each case the ice sheet had a margin frozen to its bed and an interior moving over a deforming bed. The North Taymyr ice‐marginal zone (NTZ) comprises ice‐marginal and supraglacial landsystems dominated by thrust‐block moraines 2–3 km wide and large‐scale deformation of sediments and ice. Large areas are still underlain by remnant glacier ice and a supraglacial landscape with numerous ice‐walled lakes and kames is forming even today. The proglacial landsystem is characterised by subaqueous (e.g. deltas) or terrestrial (e.g. sandar) environments, depending on location/altitude and time of formation. Dating results (OSL, ¹⁴C) indicate that the NTZ was initiated ca. 80 kyr BP during the retreat of the Early Weichselian ice sheet and that it records the maximum limit of a Middle Weichselian glaciation (ca. 65 kyr BP). During both these events, proglacial lakes were dammed by the ice sheets. Part of the NTZ was occupied by a thin Late Weichselian ice sheet (20–12 kyr BP), resulting in subaerial proglacial drainage. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Atmospheric Losses Under Dust Bombardment in the Ancient Atmospheres     

Pavlov  A. K. 《Earth, Moon, and Planets》1997,76(3):157-183

We have considered the new process of atmospheric losses - “sputtering” under bombardment by interplanetary dust. It is demonstrated that “sputtering” due to collisions with the interplanetary dust is an effective way of atmospheric gas loss (10^–4–10^–3 of the dust particles' accreting mass) and that it changes the composition of the atmospheric gases. In calculations we have taken that the dust particles collide elastically with the atoms and molecules of the atmosphere. Estimation of the effects of inelastic collisions was also considered. As a result of these collisions a part of the atmospheric atoms and molecules will have “upward” velocity and enough energy to escape. It was considered that escaping atoms can collide with the atoms of the “main” gas of the upper atmosphere. The atmospheric gas composition is assumed to be just as in the modern Martian atmosphere - the “main” gases in the upper atmosphere were taken to be O and CO₂. In our computations we pay particular attention to the abundance of noble gases in planetary atmospheres since these gases are very important for theories of atmospheric origin. We computed that under “sputtering” by the interplanetary dust, atmospheres were enriched by the “heavy” elements and isotopes in the wide range of the upper atmospheric parameters O/CO₂, T/g (O/CO₂– on the level of homosphere;T is temperature of the exosphere,g is gravitational acceleration). However the loss efficiency for “heavy” gases is relatively high compared to other known gas loss processes. In the case of noble gases for the specific parameters of the upper atmosphere (small T/g ratio; high O/CO₂ on the level of homosphere) we have got the unique result: despite the diffusion separation in the upper atmosphere the loss efficiency of Xe > Kr > Ar. The effect of “sputtering” of the planetary atmospheres was strongest during the early stages of the planetary evolution - when the rate of the dust accretion was intrinsically higher than now because of collisions of planetesimals. In light of the new escape process, the main peculiarities of the noble gases abundance in the planetary atmospheres could be explained. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

An efficient method for studying the stability and dynamics of the rotational motions of celestial bodies     

A. I. Pavlov  A. J. Maciejewski 《Astronomy Letters》2003,29(8):552-566

We use the alternative MEGNO (Mean Exponential Growth of Nearby Orbits) technique developed by Cincotta and Simó to study the stability of orbital—rotational motions for plane oscillations and three-dimensional rotations. We present a detailed numerical—analytical study of a rigid body in the case where the proper rotation of the body is synchronized with its orbital motion as 3: 2(Mercurian—type synchronism). For plane rotations, the loss of stability of the periodic solution that corresponds to a 3: 2 resonance is shown to be soft, which should be taken into account to estimate the upper limit for the ellipticity of Mercury. In studying stable and chaotic translational—rotational motions, we point out that the MEGNO criterion can be effectively used. This criterion gives a clear picture of the resonant structures and allows the calculations to be conveniently presented in the form of the corresponding MEGNO stability maps for multidimensional systems. We developed an appropriate software package.  相似文献