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Saint Petersburg, Russia

Raspopov O.M.,Institute of Terrestrial Magnetism | Lopatin E.V.,University of Eastern Finland | Kolstrom T.,Finnish Forest Research Institute | Dergachev V.A.,RAS Ioffe Physical - Technical Institute | And 3 more authors.
Izvestiya - Atmospheric and Ocean Physics | Year: 2013

Spectral analysis of tree ring data sets of Siberian spruce (Picea obovata) and Scots pine (Pinus sylvestris L.) was carried out to study the effects of climatic factors on the conifer tree radial growth in the territory of the Komi Republic. Analyses were performed for different natural subzones in the Komi Republic: the forest-tundra transition zone and the northern, middle, and southern taiga. The results show that several groups of periodicities can be found in the tree radial growth. One from groups of periodicities is related to internal processes in the atmosphere-ocean system; the other is related to the fluctuations in solar activity. © 2013 Pleiades Publishing, Ltd.

Gulyaeva T.L.,Institute of Terrestrial Magnetism
Journal of Geophysical Research: Space Physics | Year: 2012

An empirical model of storm-time behavior of the ionospheric peak height hmF2 associated with changes of peak electron density NmF2 is inferred from the topside true-height profiles provided by ISIS 1, ISIS 2, IK-19, and Cosmos-1809 satellites for the period of 1969-1987. The topside-derived quiet-time models of the ionospheric peak height hqF2 and peak electron density NqF2 are used as a frame of reference. To harmonize the model with storm and substorm effects induced by large-scale traveling ionospheric disturbances (LSTIDs), constraints are applied to the topside data, excluding their changes deviating above LSTID extreme limits. The degree of disturbance is estimated by the ionospheric weather W index; then, the least squares fitting is applied to the median of log(hm/hq) versus log(Nm/N q). Anticorrelation between instant changes of hmF 2 and NmF2 has a particular seasonal-magnetic latitude structure varying with solar activity that is used for the buildup of the analytical model. The model allows the deduction of the instantaneous h mF2 associated with the assessment or forecast of the respective NmF2. The model is validated with the data of five ground-based ionosondes during severe space weather storms at times of high solar activity (2000) and low solar activity (2006), and results agree reasonably well with the peak parameters derived from an ionogram. The model is incorporated into the coupled International Reference Ionosphere-Plasmasphere (IRI-Plas) code, used in the assimilative mode as the three-dimensional (3-D) interpolator of the GPS-derived total electron content, TECgps. © Copyright 2012 by the American Geophysical Union.

Zirakashvili V.N.,Institute of Terrestrial Magnetism
AIP Conference Proceedings | Year: 2011

Cosmic ray acceleration and magnetic amplification in supernova remnants is shortly reviewed. The results on the modeling of broadband electromagnetic emission from supernova remnants are presented. © 2011 American Institute of Physics.

Vernova E.S.,Institute of Terrestrial Magnetism | Tyasto M.I.,Institute of Terrestrial Magnetism | Baranov D.G.,RAS Ioffe Physical - Technical Institute
Geomagnetism and Aeronomy | Year: 2010

Synoptic maps for 1976-2003 obtained at the Kitt Peak National Solar Observatory are used to analyze the longitudinal distribution of the solar photospheric magnetic field. The superposition of synoptic maps gives different pictures for the rise-maximum phase and the decline-minimum phase. Two characteristic periods correspond to different situations in the 22-year solar magnetic cycle in the course of which both the global magnetic field and the magnetic field of the leading sunspot in a group change their sign. © Pleiades Publishing, Ltd., 2009.

Sidorova L.N.,Institute of Terrestrial Magnetism | Filippov S.V.,Institute of Terrestrial Magnetism
Geomagnetism and Aeronomy | Year: 2013

This work presents a new examination of the hypothesis regarding the equatorial origin of low He+ density plasma depletions (or subtroughs). For this purpose, we have conducted a detailed comparative analysis of longitudinal variations in the occurrence probabilities of subtroughs in both hemispheres and variations in the occurrence probabilities of equatorial F-region irregularities (EFIs), equatorial spread F (RFS and ESF), and equatorial plasma bubbles (EPBs). Taking into consideration the seasonal dependence and some peculiarities of magnetic field variations in different hemispheres, a conclusion has been reached regarding the similarity between longitudinal statistical occurrences of subtroughs and equatorial ionospheric F-region irregularities. In addition, another piece of evidence in favor of the similarity of the nature of the above-mentioned phenomena has been obtained. We have got a confirmation once again that low He+ density depletions (or subtroughs) can be rightfully considered as equatorial plasma "bubbles," which can be observed at altitudes of the topside ionosphere as depletions in the He+ density. © 2013 Pleiades Publishing, Ltd.

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