Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study

The dynamics of the cusp region and post-noon sector for an interval of predominantly IMF B_y, B_z < 0 nT are studied with the CUTLASS Finland coherent HF radar, a meridian-scanning photometer located at Ny Ålesund, Svalbard, and a meridional network of magnetometers. The scanning mode of the radar is such that one beam is sampled every 14 s, and a 30° azimuthal sweep is completed every 2 minutes, all at 15 km range resolution. Both the radar backscatter and red line (630 nm) optical observations are closely co-located, especially at their equatorward boundary. The optical and radar aurora reveal three different behaviours which can interchange on the scale of minutes, and which are believed to be related to the dynamic nature of energy and momentum transfer from the solar wind to the magnetosphere through transient dayside reconnection. Two interpretations of the observations are presented, based upon the assumed location of the open/closed field line boundary (OCFLB). In the first, the OCFLB is co-located with equatorward boundary of the optical and radar aurora, placing most of the observations on open field lines. In the second, the observed aurora are interpreted as the ionospheric footprint of the region 1 current system, and the OCFLB is placed near the poleward edge of the radar backscatter and visible aurora; in this interpretation, most of the observations are placed on closed field lines, though transient brightenings of the optical aurora occur on open field lines. The observations reveal several transient features, including poleward and equatorward steps in the observed boundaries, braiding of the backscatter power, and 2 minute quasi-periodic enhancements of the plasma drift and optical intensity, predominantly on closed field lines.     

Long-Term Stability Of Geoidal Geopotential FromTopex/Poseidon Satellite Altimetry 1993–1999

The TOPEX/POSEIDON (T/P) satellite altimeter data from January 1, 1993to October 24, 1999 (cycles 11–261) was used for investigating thelong-term variations in the geoidal geopotential W₀ and/orin the geopotential scale factor R₀ = GM/W₀ (GM is theadopted geocentric gravitational constant). The mean valuesdetermined for the whole period covered are: W₀ =(62 636 856.161 ± 0.002) m² s^-2, R₀ =(6 363 672.5448 ± 0.0002) m. The actual accuracy is limited bythe altimeter calibration error (2–3 cm) and it isestimated to be about ± 0.5 m² s^-2 (± 5 cm).The yearly variations of the above mean values are at the formalerror level. No long-term trend in W₀, representing the oceanvolume change, was found for the seven years period 1993–9 on thebasis of T/P altimeter (AVISO) data. No sea surface topography modelwas used in the solution. This revised version was published online in July 2006 with corrections to the Cover Date.     

Geoidal curvature radii from satellite data for different degrees of smoothing

Summary Radii of curvature and their anomalies of a smoothed geoidal surface are computed using Stokes's constants J _n ^(k) , S _n ^(k) of the Earth's body, obtained from satellite orbit dynamics[2]. Different degrees n of smoothing are used (n = 8, 12, 21). The notations are the same as in[4, 5].     

Daily variations of the characteristics of beating-typePc3 (Bpc3) pulsations

Summary The spectra of nearly 100 samples of Bpc3 pulsations were computed in the X and Y components of data from the Budkov Observatory. These spectra were used to study the daily variations of the fundamental characteristics of the pulsations, the frequency f ₀ and amplitude A ₀ of the main spectral peaks. The daily variation of the ellipticity of the polarization ellipses of oscillations in frequency f ₀ was also studied in the XY-plane.Part of these results was reported at the XVth General Assembly of the IUGG, Moscow, August 1971.     

The telluric field in a halfspace with a spherical inhomogeneity

Summary An exact solution of the distribution of the intensity of the telluric field in a halfspace with a spherical inhomogeneity has been obtained by solving the Laplace equation in bipolar coordinates. This exact solution is compared with the presently known approximate solution, obtained by the method of images, and the region of their coincidence has been determined. For the image solution theoretical relations have been derived for computing the anomaly of the magnetic field. Craphs depict many of the properties of the telluric and magnetic fields on the surface of the considered halfspace for various parameters of the given problem.Dedicated to 90th Birthday of Professor Frantiek Fiala     

Equations of motion of the moon retaining higher harmonics in the force function

u u u u uu smu um ¶rt;um ¶rt; a, s¶rt;a ¶rt;a ¶rt;u suu (n — mn, k — n¶rt;): saumauo n u: n=2, k=0; n=2, k=2; n=3, k=0, 1, 2, 3; n=4, k=0; n=4, k=3; saumau n : n=2, k=0; n=2, k=2; saumau n a: n=2, k=0.

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Dedicated to Prof. RNDr. Emil Buchar, DrSc., Corresponding Member of the Czechoslovak Academy of Sciences, on the Occasion of His 75^th Birthday     

Expansion of a function given over an equipotential surface into spherical harmonics

¶rt;m ¶rt; uuauu uum auu uu, a¶rt;a a nmunmuaa, ¶rt; n uu u. aa, m u u ¶rt;um nmu, uu n¶rt; m nm, u aaaa u aa m nmua.     

Two-component spectral analysis of geomagneticpi2 pulsations

Summary The method of two-component spectral analysis is described in two versions: as the so-called static analysis, in which the pulsation sample being studied is treated as a whole, and as the dynamic analysis, in which the given sample is processed piecewise in order to determine the time variations of various parameters. Both versions were applied to geomagnetic pi2 pulsations. The pi2 oscillations are resolved into several frequency components. The properties of these components are studied in dependence on the frequency and local time. The time variation of the amplitude (attenuation) and the polarization characteristics (precession) of pi2's are also studied.     

Spectra and polarization characteristics of geomagneticPc4 pulsations recorded at field station štrkovec

ama nm u nmam nuau aamumuuaum nau muna Pc4 n ¶rt;a u mauu m, a¶rt; a m m anam ¶rt;u amu u¶rt;a umu. n¶rt;a auum nu¶rt;a u anum¶rt; nau u u nuau aamumu mu ¶rt; u m aum amumu, u au uu m¶rt; naam. mam auam mamau amu nau Pc3 u Pi2 n ¶rt;a u mau ¶rt; u u.