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The 2009-2012 Ionosonde and IRI2012 Variability of foF2, hmF2, M3000F2, B0, B1 Parameters over Warsaw

Szwabowski M., Dziak-Jankowska B., Pożoga M., Tomasik Ł.

Acta Geophysica

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2016

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Vol. 64, no. 4

1211--1223

EN

This paper presents comparisons of variability and accordance of ionospheric parameters foF2, hmF2, M3000F2, B0, B1 over the middle latitude station in Warsaw (52.21°N, 21.06°E). Examination included observational data from Space Research Centre ionosonde in Poland and International Reference Ionosphere (IRI) 2012 model, for the time period of increasing solar activity from 2009 to 2012. The analysis concerned: trend, monthly median differences in twenty-four hours variability, local minima and maxima. Results are presented as tables of semi-annual data, and plots of difference in four-year period. The study indicated good agreement of foF2 and hmF2 parameters. Underestimations of B1 and M3000F2, variability of B0 parameter in Bil-2000, Gul-1987, and ABT- 2009 option, were taken into consideration.

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Extension of EGNOS ionospheric correction coverage area

Swiatek A., Stanislawska I., Zbyszynski Z., Dziak-Jankowska B.

Acta Geophysica

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2014

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Vol. 62, no. 1

259--269

EN

Ionosphere coverage is likely to be a driver for the EGNOS coverage area. Hence, a study considering a dedicated ionosphere algorithm to improve the ionosphere coverage area has been conducted. The logic of the study is the following: the accuracy of the GPS signal depends mainly on the total electron content (TEC). At two close points, TEC changes in time in a very similar way; these are region dependent variables. This correlation decreases with growing distance between the observation points and is anisotropic. Based on TEC variogram analysis, the specific algorithm has been developed. This specific algorithm is presented and discussed.

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Sublimation-driven evolution of the local radius and the moment of inertia of short-period comets

Dziak-Jankowska B.

Acta Geophysica

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2010

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Vol. 58, no. 2

392-416

EN

This article is a continuation of the previous one considering the evolution of a long-period comet. The changes of the local radius and the moment of inertia as well as the orientation of the rotation axis are calculated. With reference to the previous model, the time-dependent orbital parameters are introduced. The procedure of sublimation-driven evolution is implemented to the comets 67P/Churyumov-Gerasimenko, 9P/Tempel 1, and 81P/Wild. The inclination of the rotation axis of Comet Ch-G is calculated. The position of the rotation axis is a result of the best fit of the water production rate curve received from modelling to the observational water production rate curve. The method is verified through application to Comets 9P/Tempel 1 and 81P/Wild with wellknown positions of the rotation axes. The best fit is for inclination of the rotation axis which is close to the position of the rotation axis with minimum energy (maximum of the moment of inertia). For the best fitted position of the rotation axis I = 90 and Ø= 60 degrees, the largest decrease of radius was about 5.6 m in the northern polar region. The smallest decrease of radius, of about 0.3 m, was noticed on cometographic latitudes between 39 and 46 degrees.

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Sublimation-driven evolution of the local radius and the moment of inertia of a long-period comet

Dziak-Jankowska B., Leliwa-Kopystyński J., Kossacki K.

Acta Geophysica

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2009

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Vol. 57, no. 2

509-535

EN

In this paper we intend to analyze how the sublimation of ice from cometary nuclei affects changes of the moments of inertia. Our aim is to show general trends for different orientations of cometary nucleus' rotation axis. Thus we apply numerical model of a hypothetical homogeneous and initially spherical nucleus composed of water ice and dust. As an example we present simulations for a model comet of the orbital elements and the nucleus size the same as determined for C/1995 O1 Hale-Bopp, a widely analyzed long-period comet. We calculated water production from the nucleus and changes of the shape (initially spherical) and of the moment of inertia versus time. Simulations are performed for the full range (0-90°) of inclinations I of the rotation axis. The second paramater related to the orientation of the rotation axis is the argument Φ (0-360°). The heat conductivity of the nucleus spans over the vast range, 0.04-4 W m⁻¹ K⁻¹.