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Your search keyword '"Gordeev, E. I."' showing total 175 results
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175 results on '"Gordeev, E. I."'

34. Diagnostics of Closed Magnetic Flux Depletion in the Near-Earth Magnetotail During the Substorm Growth Phase

Author

Shukhtina, M. A., Gordeev, E. I., Sergeev, V. A., and Shinohara, Iku

Subjects
Physics, Geophysics, 010504 meteorology & atmospheric sciences, Space and Planetary Science, Growth phase, 0103 physical sciences, Substorm, 010303 astronomy & astrophysics, 01 natural sciences, Earth (classical element), Magnetic flux, 0105 earth and related environmental sciences
Abstract

Accepted: 2018-09-29, 資料番号: SA1180157000

Published
2018

47. The energy‐based scaling of a thin current sheet: Case study

Author

Sasunov, Yu. L., Khodachenko, M. L., Alexeev, I. I., Belenkaya, E. S., Gordeev, E. I., and Kubyshkin, I. V.

Subjects
Solar Physics, Astrophysics, and Astronomy, adiabatic invariant, Energetic Particles, Kinetic and MHD theory, Cluster observation, Cosmic Rays, Research Letters, Interplanetary Physics, Particle Acceleration, Physics::Plasma Physics, current sheet, Physics::Space Physics, Plasma Sheet, Research Letter, Space Plasma Physics, Magnetospheric Physics, Space Sciences
Abstract

The influence of average plasma energy E~ on the half thickness ℓ of a thin current sheet (TCS) is investigated for three cases of TCSs crossings. The value of ℓ was estimated from the magnetic field data by means of Cluster observations. The obtained scaling values for TCSs, Z~=ℓ/ρT, where ρ T is the thermal Larmor radius, were compared with the scaling Zμ=22E~/T, where E~ and T are the average plasma energy and the temperature of plasma, which assumes a specific dynamics (conservation of magnetic flux through the trajectory segment) of the current carriers. The comparison of Z~ and Z μ shows a good agreement., Key Points The new scaling is presentedThe energy‐based scaling compared with observable thickness of TCSThe population of the TCS‐forming protons results in different scaling

Published
2015

48. Retrieving robust noise-based seismic velocity changes from sparse data sets: synthetic tests and application to Klyuchevskoy volcanic group (Kamchatka)

Author

Repsol, Ministry of Education and Science of the Russian Federation, European Research Council, Science Foundation Ireland, Université de Paris, Gómez-García, Clara [0000-0002-9616-9374], Gómez-García, Clara, Brenguier, F., Boue, P., Shapiro, N. M., Droznin, D. V., Droznina, S. Ya., Senyukov, S. L., Gordeev, E. I., Repsol, Ministry of Education and Science of the Russian Federation, European Research Council, Science Foundation Ireland, Université de Paris, Gómez-García, Clara [0000-0002-9616-9374], Gómez-García, Clara, Brenguier, F., Boue, P., Shapiro, N. M., Droznin, D. V., Droznina, S. Ya., Senyukov, S. L., and Gordeev, E. I.

Abstract

Continuous noise-based monitoring of seismic velocity changes provides insights into volcanic unrest, earthquake mechanisms and fluid injection in the subsurface. The standard monitoring approach relies on measuring traveltime changes of late coda arrivals between daily and reference noise cross-correlations, usually chosen as stacks of daily cross-correlations. The main assumption of this method is that the shape of the noise correlations does not change over time or, in other terms, that the ambient-noise sources are stationary through time. These conditions are not fulfilled when a strong episodic source of noise, such as a volcanic tremor, for example, perturbs the reconstructed Green's function. In this paper, we propose a general formulation for retrieving continuous time-series of noise-based seismic velocity changes without the requirement of any arbitrary reference cross-correlation function (CCF). Instead, we measure the changes between all possible pairs of daily cross-correlations and invert them using different smoothing parameters to obtain the final velocity change curve. We perform synthetic tests in order to establish a general framework for future applications of this technique. In particular, we study the reliability of velocity change measurements versus the stability of noise CCFs. We apply this approach to a complex data set of noise cross-correlations at Klyuchevskoy volcanic group (Kamchatka), hampered by loss of data and the presence of highly non-stationary seismic tremors.

Published
2018

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