Search Results - "Kovaltsov, G.A."

Analysis of Ground Level Enhancements (GLE): Extreme solar energetic particle events have hard spectra by Asvestari, E., Willamo, T., Gil, A., Usoskin, I.G., Kovaltsov, G.A., Mikhailov, V.V., Mayorov, A.

“…Nearly 70 Ground Level Enhancements (GLEs) of cosmic rays have been recorded by the worldwide neutron monitor network since the 1950s depicting a big variety…”
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Updated model of cosmic-ray-induced ionization in the atmosphere (CRAC:CRII_v3): Improved yield function and lookup tables by Usoskin, I.G., Kovaltsov, G.A., Mishev, A.L.

“…Cosmic rays, including galactic cosmic rays and solar energetic particles, form the main source of ionization of the low and middle atmosphere, which is…”
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Correlation between clouds at different altitudes and solar activity: Fact or Artifact? by Usoskin, I.G., Voiculescu, M., Kovaltsov, G.A., Mursula, K.

“…Studies of the relation between cosmic rays (CR) (solar activity) and atmospheric cloudiness are mostly based on the satellite ISCCP cloud data. However,…”
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Reconstruction of Monthly and Yearly Group Sunspot Numbers From Sparse Daily Observations by Usoskin, I G, Mursula, K, Kovaltsov, G A

“…Some periods before 1820 are poorly covered by sunspot observations. In addition to apparent, long observational gaps, there are also periods when there are…”
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Modeling the propagation of solar energetic particles in corotating compression regions of solar wind by Kocharov, L., Kovaltsov, G.A., Torsti, J., Anttila, A., Sahla, T.

“…We present the first modeling of solar energetic particle (SEP) events inside corotating compression regions. We consider gradual compressions in the…”
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Cosmogenic 7Be in air: A complex mixture of production and transport by Leppänen, A.-P., Pacini, A.A., Usoskin, I.G., Aldahan, A., Echer, E., Evangelista, H., Klemola, S., Kovaltsov, G.A., Mursula, K., Possnert, G.

“…The long-time series of 7Be activity in surface air have been studied with the wavelet analysis technique in order to find coherence between 7Be activity,…”
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Cosmic ray-induced ionization in the atmosphere: spatial and temporal changes by Usoskin, I.G., Gladysheva, O.G., Kovaltsov, G.A.

“…Detailed calculations of the time-variable spatial distribution of cosmic ray-induced ionization of the lower atmosphere are presented using a physical model…”
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Regional millennial trend in the cosmic ray induced ionization of the troposphere by Usoskin, I.G., Mironova, I.A., Korte, M., Kovaltsov, G.A.

“…Long-term trends in the tropospheric cosmic ray induced ionization on the multi-millennial time scale are studied using the newly released paleomagnetic…”
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Cosmogenic 7Be and 22Na in Finland: Production, observed periodicities and the connection to climatic phenomena by Leppänen, A.-P., Usoskin, I.G., Kovaltsov, G.A., Paatero, J.

“…This study presents theoretical production calculations and time series analyses of two cosmogenic isotopes, 7Be and 22Na, from the four high-latitude stations…”
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Case study of Forbush decreases: Energy dependence of the recovery by Jämsén, T., Usoskin, I.G., Räihä, T., Sarkamo, J., Kovaltsov, G.A.

“…Case study is presented for three Forbush decreases in 2004–2005, using cosmic ray data from ground-based detectors – neutron monitors and a muon detector. One…”
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Cyclic variations of the heliospheric tilt angle and cosmic ray modulation by Alanko-Huotari, K., Usoskin, I.G., Mursula, K., Kovaltsov, G.A.

“…Using data on cosmic ray modulation parameter since 1951, we have estimated the evolution of the heliospheric current sheet tilt angle for the period…”
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The impact of interplanetary transport on the charge spectra of heavy ions accelerated in solar energetic particle events by Kartavykh, Y.Y., Dröge, W., Kovaltsov, G.A., Ostryakov, V.M.

“…The effect of interplanetary propagation on the energy dependence of the iron mean ionic charge of solar cosmic rays is investigated. The diffusion–convection…”
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Dependence of cosmic rays on solar activity for odd and even solar cycles by Usoskin, I.G., Mursula, K., Kananen, H., Kovaltsov, G.A.

“…We study the relationship between solar activity and cosmic ray intensity for the last four full cycles, using the time delayed component method (Usoskin et…”
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Heliospheric modulation strength: effective neutron monitor energy by Alanko, K., Usoskin, I.G., Mursula, K., Kovaltsov, G.A.

“…The widely used concept of the neutron monitor energy range is not well defined. Also, the median energy of a neutron monitor varies in the course of the solar…”
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A 22-year cycle in sunspot activity by Mursula, K., Usoskin, I.G., Kovaltsov, G.A.

“…We study the recently presented group sunspot number series and show that a persistent 22-year periodicity exists in sunspot activity throughout the entire…”
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The 1990 May 24 solar cosmic-ray event by Torsti, J., Kocharov, L.G., Vainio, R., Anttila, A., Kovaltsov, G.A.

“…This paper presents an integrated analysis of GOES 6, 7 and neutron monitor observations of solar cosmic-ray event following the 1990 May 24 solar flare. We…”
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Nitrate abundance in polar ice during the great solar activity minimum by Gladysheva, O.G., Kocharov, G.E., Kovaltsov, G.A., Usoskin, I.G.

“…In the present paper we study variations of the nitrate content in Greenland ice core for the last 400 years. These data were obtained by high-precision…”
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Sensitivity of a neutron monitor to galactic cosmic rays by Usoskin, I.G., Bobik, P., Gladysheva, O.G., Kananen, H., Kovaltsov, G.A., Kudela, K.

“…We studied the sensitivity of a neutron monitor to Galactic cosmic rays depending on energy of cosmic ray particles in the interstellar medium. This is…”
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Monte-Carlo approach to galactic cosmic ray propagation in the heliosphere by Gervasi, M., Rancoita, P.G., Usoskin, I.G., Kovaltsov, G.A.

“…In the present paper we consider a possibility of using stochastic simulation (Monte-Carlo) technique approach to the study of Galactic Cosmic Ray propagation…”
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