Hook-shaped arcs in dayside polar cap and their relation to the IMF

A special type of auroral forms has been revealed in the southern polar cap on the basis of Vostok station data. There are hook-shaped arcs consisting of sun-aligned polar cap arcs which convert into latitude-oriented oval arcs. These hook-shaped arcs are seen in the southern polar cap only when B_z, component of the IMF is northward and B_x > 0. The sun-aligned arcs are grouped in the prenoon sector when B_y is positive and they are displaced in the afternoon sector when B_y is negative. When B_y is near zero the sun-aligned arcs are set almost symmetrically relative to the noon meridian. If the hook-shaped arcs display a convection pattern, the occurrence of twin hooks would seem to be in favour of a throat form of the sunward plasma flows exiting the polar cap.     

Interaction of particles with ion cyclotron waves and magnetosonic waves. Observations from GEOS 1 and GEOS 2

Coordinated observations involving ion composition, thermal plasma, energetic particle, and ULF magnetic field data from GEOS 1 and 2 often reveal the presence of electromagnetic ion cyclotron and magnetosonic waves, which are distinguished by their respective polarization characteristics and frequency spectra. The ion cyclotron waves are identified by a magnetic field perturbation that lies in a plane perpendicular to the Earth's magnetic field B₀ and propagate along B₀. They are associated with the abundance of cold He⁺ in the presence of anisotropic pitch angle distributions of ions having energies E > 20 keV, and were observed at frequencies near the He⁺ gyrofrequency. The magnetosonic waves are characterized by a magnetic field perturbation parallel to B₀ and thus seem to be propagating perpendicular to the Earth's magnetic field. They often occur at harmonics (not always including the fundamental) at the proton gyrofrequency and are associated with phase-space-density distributions that peak at energies E ～ 5–30 keV and at a pitch angle of 90°. Such a ring-like distribution is shown to excite instability in the magnetosonic mode near harmonics of the proton gyrofrequency. Magnetosonic waves are associated in other cases with sharp spatial gradients in energetic ion intensity. Such gradients are encountered in the early afternoon sector (as a consequence of the drift shell distortion caused by the convection electric field) and could likewise constitute a source of free energy for plasma instabilities.     

Subsurface Meridional Flow from HMI Using the Ring-Diagram Pipeline

We have determined the meridional flows in subsurface layers for 18 Carrington rotations (CR 2097 to 2114) analyzing high-resolution Dopplergrams obtained with the Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO). We are especially interested in flows at high latitudes up to 75^° in order to address the question whether the meridional flow remains poleward or reverses direction (so-called counter cells). The flows have been determined in depth from near-surface layers to about 16 Mm using the HMI ring-diagram pipeline. The measured meridional flows show systematic effects, such as a variation with the B ₀-angle and a variation with central meridian distance (CMD). These variations have been taken into account to lead to more reliable flow estimates at high latitudes. The corrected average meridional flow is poleward at most depths and latitudes with a maximum amplitude of about $20~\mathrm{m\,s}^{-1}$ near 37.5^° latitude. The flows are more poleward on the equatorward side of the mean latitude of magnetic activity at 22^° and less poleward on the poleward side, which can be interpreted as convergent flows near the mean latitude of activity. The corrected meridional flow is poleward at all depths within ±?67.5^° latitude. The corrected flow is equatorward only at 75^° latitude in the southern hemisphere at depths between about 4 and 8 Mm and at 75^° latitude in the northern hemisphere only when the B ₀ angle is barely large enough to measure flows at this latitude. These counter cells are most likely the remains of an insufficiently corrected B ₀-angle variation and not of solar origin. Flow measurements and B ₀-angle corrections are difficult at the highest latitude because these flows are only determined during limited periods when the B ₀ angle is sufficiently large.     

Magnetic instability in a rotating layer at highly eccentric positions of the critical level

This study follows the numerical results presented in Marsenić & Ševčík (2010) that explored the influence of the critical level position on stability of a system. The model was a horizontal fluid layer between z = ±0.5d rotating with an angular velocity Ω = Ω₀ ž about the vertical axis z . The fluid was considered to be inviscid, finitely electrically conducting and incompressible and was permeated by a horizontal magnetic field B ₀ = ℬ︁₀B₀(z) y̌ , where ℬ︁₀ was the magnitude of the field and the function B₀(z) = tanh [γ (z –z₀)]. When γ is large, the field gradient is concentrated near z = z₀, the critical level, the field being almost homogeneous elsewhere. In this way it controls the width of the magnetic shear layer associated with the current sheet. It was found that at conditions when the magnetic field gradient was large enough (γ = O (10)) and the critical level was placed close enough to the (bottom) perfectly conducting boundary (z₀ < –0.388d for γ = 80), magnetically driven convection appeared localized to a close neighbourhood of the critical level – the so called critical layer. Based on the circumstances of its rise and its properties it was identified with the resistive tearing‐mode instability. This paper presents an analytical treatment of the problem assuming γ ≥ 1. The approach consists in separation of the computational domain into an outer region where the diffusionless limit (Elsasser number Λ → ∞) applies and an inner region (the critical layer) of finite conductivity. According to the tearing‐mode theory in classical systems, the solution in the inner region is sought as long‐wavelength with respect to the width of the critical layer. The obtained solution shows features similar to the one obtained numerically and confirmed relevance of the simplifying physical assumptions made in each region. The convection in the critical layer is strictly conditioned by a sharp magnetic shear. If the shear region is removed by further positioning of the critical level towards the perfectly conducting boundary, the localized convection disappears. It is in compliance with the fact that the system is stabilised by a perfectly conducting boundary with respect to the tearing mode. Stability is then checked numerically in the layer bounded by perfectly conducting boundaries where the critical point of the magnetic field lies on one of them. The existence of a magnetically driven instability is confirmed. Depending on the value γ, it may rise as a stationary convection (for γ < 1.5) or as a wave which for γ > 16 exhibits similarity properties (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dawn-dusk (y) component of the interplanetary magnetic field and the local time of the harang discontinuity

We describe a simple method for determining the time at which the meridian of a sub-auroral magnetic observatory crosses that of the Harang discontinuity—the separation of the eastward and westward electrojets which flow in the evening and morning sectors of the auroral oval. We then consider how this time, determined from examination of magnetograms from sub-auroral observatories varies with the dawn-dusk (y) component of the Interplanetary Magnetic Field. We find that the time at which the Harang discontinuity is identified in the Northern Hemisphere is earlier for B_y > 0 than the occasions when B_y < 0, and that the converse is observed in the Southern Hemisphere. Also we suggest that there is no significant seasonal variation in the relationship between the time of the discontinuity and B_y. The sense of the azimuthal shift of the auroral electrojet currents with changes in B_y is consistent with the theory of Cowley (1981). However, the magnitude of the observed shifts is approximately an order of magnitude greater than the theoretical predictions. We suggest that this difference between observation and theory arises from the use of a dipole magnetic field model at auroral zone latitudes in the theoretical estimation of azimuthal displacement.     

Auroral boundary variations and the interplanetary magnetic field

This paper describes a DMSP data set of 150 auroral images during magnetically quiet times which have been analyzed in corrected geomagnetic local time and latitudinal coordinates and fit to offset circles. The fit parameters R (circle radius) and (X, Y) (center location) have been compared to the hourly interplanetary magnetic field (IMF) prior to the time of the satellite scan of the aurora. The results for variation of R with B_z, agree with previous works and generally show about a 1° increase of R with increase of southward B_z by 1 nT. The location of the circle center also has a clear statistical shift in the Southern Hemisphere with IMF B_y such that the southern polar cap moves towards dusk (dawn) with B_y > (B_y < 0).     

On the distribution of By in the geomagnetic tail

The distribution of B_y in the geomagnetic tail associated with a net cross-tail magnetic flux, recently experimentally discovered, is here investigated within the framework of two-dimensional but non-planar field adiabatic time-independent equilbria. It is found that the flux distribution is controlled by the pressure anisotropy of the plasma, B_y being enhanced at the current sheet centre relative to that in the lobes for P_∥>P_⊥ and vice-versa for P_⊥>P_∥. For P_⊥>P_∥ a broad region of depressed field strength is found across the centre plane of the current sheet, terminated at its outer boundaries by spikes in the perpendicular current, across which B_y and B_x are “switched on” and rapidly increase towards their values in the low-β lobes. For P_∥>P_⊥ a thin high-current density layer forms at the sheet centre if the marginal firehose condition is approached, across which the B_x field reverses by rotation at nearly constant magnitude about the z-axis. The field magnitude in this thin layer depends upon the pressure anisotropy, such that the plasma remains just firehose stable within it, and may approach an appreciable fraction of the lobe field strength even for moderate anisotropies. Such structures have been observed in the geomagnetic tail, but do not appear to be a common feature of the quiet-time plasmasheet, where the field strength at the centre plane can reach small values with little obvious enhancement of B_y. In terms of the present model these observations require that either P_⊥>P_∥ in the quiet-time tail or that the plasma is within one or two per cent of isotropy if P_∥>P_⊥. These results then indicate that the production of plasma pressure anisotropy during adiabatic inward transport towards the Earth, which is generally expected to lead to P_∥>P_⊥ and its destruction by either macroscopic or microscopic processes, requires further study.     

North – South Asymmetry of Zonal and Meridional Flows Determined From Ring Diagram Analysis of Gong ++ Data

We study the North–South asymmetry of zonal and meridional components of horizontal, solar subsurface flows during the years 2001–2004, which cover the declining phase of solar cycle 23. We measure the horizontal flows from the near-surface layers to 16 Mm depth by analyzing 44 consecutive Carrington rotations of Global Oscillation Network Group (GONG) Doppler images with a ring-diagram analysis technique. The meridional flow and the errors of both flow components show an annual variation related to the B ₀-angle variation, while the zonal flow is less affected by the B ₀-angle variation. After correcting for this effect, the meridional flow is mainly poleward but it shows a counter cell close to the surface at high latitudes in both hemispheres. During the declining phase of the solar cycle, the meridional flow mainly increases with time at latitudes poleward of about 20^˚, while it mainly decreases at more equatorward latitudes. The temporal variation of the zonal flow in both hemispheres is significantly correlated at latitudes less than about 20^˚. The zonal flow is larger in the southern hemisphere than the northern one, and this North–South asymmetry increases with depth. Details of the North–South asymmetry of zonal and meridional flow reflect the North–South asymmetry of the magnetic flux. The North–South asymmetries of the flows show hints of a variation with the solar cycle.     

The slender solar tachocline: a magnetic model

A model for the sharp transition from differential rotation in the solar convection zone to rigid rotation in the radiative interior is presented. Differential rotation in the radiative zone is shown to be quenched efficiently by an internal magnetic field. The poloidal field amplitude, B₀, is the input parameter for our model which determines the transition layer thickness and the toroidal field strength. It is illustrated analytically and confirmed numerically that a rather small field, B₀ = 10⁻⁴ Gauss, suffices to satisfy the helioseismological restrictions on the depth of the differential rotation penetration below the convection zone. The transition layer thickness decreases further with increasing B₀. The toroidal field amplitude B ≃ 200 Gauss is almost independent of B₀.     

Asymmetry effects associated with the x-component of the IMF in a magnetically open magnetosphere

The origin of magnetospheric asymmetry effects associated with the equatorial plane component of the interplanetary magnetic field (IMF) is discussed in terms of the forces exerted on open flux tubes mapping into the solar wind. It is argued that the downstream relaxation of the magnetosphere under the action of these stresses towards a state of reduced stress is such as to allow, in effect, partial penetration of this field component (both B_x and B_y in magnetospheric coordinates) into the magnetosphere. Many of the associated phenomena are therefore qualitatively described by the ‘dipole plus uniform IMF’ model, since this represents the idealization of exactly zero electromagnetic stress and hence gives a lowest order picture of the effects which result from magnetospheric relaxation toward that state. This is true of IMF B_y-associated effects which are well documented experimentally and which form a rich and consistent set of phenomena which have received considerable attention over the past decade. It is argued here that exactly corresponding phenomena are expected to be associated with the IMF B_x field as well, but because of the differing field direction these will take differing and usually less obvious forms than the similar effects associated with B_y. The suggested partial penetration of the IMF B_x field should be directly testable in the dipolar field region of the magnetosphere, but in the tail North-South displacements of the current sheet (and possibly magnetopause) are expected to occur instead. Some evidence of the latter displacements are presented. The other major IMF B_x effect should be noon-midnight displacements of the polar cap, such as have been recently reported. Little IMF B_x effect on auroral zone flows is anticipated, by contrast with the dawn-dusk asymmetries in this flow associated with IMF B_y.     

Thermal convection in the porous methane-soaked regolith in Titan: Finite amplitude convection

Titan is the only body, beside the Earth, where liquid is present on the surface. This paper is aimed to show the properties of possible convection in a porous regolith on Titan. In our previous work (Czechowski, L., Kossacki, K.J. [2009]. Icarus 202, 599–607) we showed, that the Rayleigh number Ra can exceed its critical value Ra_c. Hence, the convective motion of liquid filling pores in the regolith is likely for Titan relevant parameters. In the present work we investigate the properties of finite amplitude convection, i.e. for Ra > Ra_cr. We study the basic properties of the steady state solution, the Nusselt number, the density of the heat flow and the average temperatures. Evolution of the convection is also considered. We conclude that any reasonable thermal model of Titan’s regolith should take into account the possibility of the considered convection. We discuss also possibility of identification of this convection (or its consequences in the form of evaporates) by the Cassini and possible future spacecrafts.     

Local time asymmetry in the characteristics of Pc5 magnetic pulsations

The wave characteristics of Pc5 magnetic pulsations are analyzed with data of OGO-5, ISEE-1 and -2 satellites. The toroidal modes (δB_D >δB_H) of Pc5 pulsations are observed at a higher magnetic latitude in the dawnside outer magnetosphere. The compressional and poloidal modes (δB_z.dfnc; ～ δB_H >δB_D) of Pc5 pulsations are mostly observed near the magnetic equator in the duskside outer magnetosphere. This L.T. asymmetry in the occurrence of dominant modes of Pc5's in space can be explained by the velocity shear instability (Yumoto and Saito, 1980) in the magnetospheric boundary layer, where Alfvénic signals in the IMF medium are assumed to penetrate into the magnetospheric boundary layer along the Archimedean spiral. The asymmetrical behaviour of Pc5 pulsation activity on the ground across the noon meridian can be also explained by the ionospheric screening effect on the compressional Pc5 magnetic pulsations. The compressional modes with a large horizontal wave number in the duskside magnetosphere are expected to be suppressed on the ground throughout the ionosphere and atmosphere.     

Zonal structure and meridional drift of large-scale solar magnetic fields

Digitized synoptic charts of photospheric magnetic fields were analyzed for the past 4 incomplete solar activity cycles (1969–2000). The zonal structure and cyclic evolution of large-scale solar magnetic fields were investigated using the calculated values of the radial B _r, |B _r|, meridional B _θ, |B _θ|, and azimuthal B _φ, |B _φ| components of the solar magnetic field averaged over a Carrington rotation (CR). The time–latitude diagrams of all 6 parameters and their correlation analysis clearly reveal a zonal structure and two types of the meridional poleward drift of magnetic fields with the characteristic times of travel from the equator to the poles equal to ∼16–18 and ∼2–3 years. A conclusion is made that we observe two different processes of reorganization of magnetic fields in the Sun that are related to generation of magnetic fields and their subsequent redistribution in the process of emergence from the field generation region to the solar surface. Redistribution is supposed to be caused by some external forces (presumably, by sub-surface plasma flows in the convection zone).     

Hydromagnetic waves driven by velocity shear instability in the magnetospheric boundary layer

The bulk flow of the solar wind plasma in the flank-side of the magnetospheric boundary layer, where the magnetic field lines are closed, has a component transverse to the ambient field. There is quite a strong velocity shear. The theoretical model ignores inhomogeneities in the ambient field and the mass density which occur at the magnetopause on about the same length scale as that of the velocity shear.Consideration is restricted to hydromagnetic waves which have a k-vector nearly normal to the B_o-V_o plane, i.e., approximately the magnetopause surface (k_x >k_z ～ k_y′k_xL_B > 1 and L_B = 0.1 ～ 1.0 R_E where L_B is a characteristic length of the boundary layer). It is found that a long-period (T ? 40 sec) hydromagnetic wave [the Alfvén-like wave ($\text{Ω}{}_{\mathrm{<mtext>A</mtext>}}$)] driven by velocity shear instability can be excited in the shear plasma. It is also found that the group velocity of the HM-wave is directed almost along the magnetic field line and that the magnetic variance in the shear plasma tends to be parallel to the B_o-V_o plane. The velocity shear instability in the magnetospheric boundary layer is judged to be a likely source of long-period magnetic pulsations.     

Convection driven by tidal and radiogenic heating in medium size icy satellites

Convection is one of the most important processes responsible for the formation of the surface features on many planetary bodies. Observations of some icy satellites indicate that the satellites’ surfaces are modified due to the internally driven tectonic activity. The tidal heating could be an important source of energy responsible for such internal activity. This suggestion is supported by the correlation of the tidal parameter ψ and tectonic features. Consequently, the tidal and the radiogenic heat sources seem to be of primary importance for the medium size icy satellites. Our research deals with convection in a non-differentiated body. The convection is a results of both uniform radiogenic heating and non-uniform and non-spherically symmetric tidal heating. To investigate the problem a 3D model of convection is developed based on the Navier-Stokes equation, the equation of thermal conductivity, the equation of continuity, and the equation of state. The 3D formulae for the tidal heat generation based on the results of Peale and Cassen [1978. Icarus 36, 245-269] and others are used in the model. To measure the relative importance of radiogenic heating versus tidal heating a dimensionless number C_t is introduced. The systematic investigation of a steady-state convection is performed for different values of the Rayleigh number and for the full range of C_t. The results indicate that for low and moderate value of the Rayleigh number, convection pattern driven by the tidal heating and by the radioactivity in the medium size icy satellites consists of one cell or of two cells. For C_t>0 the critical value of Rayleigh number Ra_cr=0. The one-cell pattern is specific for low Rayleigh numbers but it could be observed for the full range of number C_t. It means that the pattern of convection does not fully follow the pattern of heating. This rather unexpected result could be of great importance for the final stage of convection. All patterns of tidally driven convection are oriented with respect to the direction to the planet. For two-cell patterns the regions of downward motion are situated in the centers of the near and far sides of the satellite, respectively.     

The eastward electrojet in the dawn sector

Many previous researchers have shown that convection in the magnetosphere is reflected in the ionosphere by an eastward electrojet in the evening sector and a westward electrojet in the post-midnight sector. In this paper we shall demonstrate the existence of eastward electrojet flow in the dawn sector in the latitude regime normally occupied by the westward convection electrojet. It will be shown that the convection westward electrojet near dawn may co-exist with the eastward electrojet while lying poleward of it. It is suggested that this eastward electrojet consists of Pedersen current flow driven by an eastward electric field and it is shown that the field lines which penetrate the eastward electrojet are populated by energetic electrons normally associated with the plasma sheet as well as high energy electrons normally associated with the trapped particle population. The high conductivity channel is generated by processes associated with the precipitation of high energy (E > 20 keV) electrons drifting eastwards from midnight in the trapping region. It is further shown that antiparallel current sheets may flow on the magnetic lines of force penetrating the electrojet, and that this flow is closed in the ionosphere by Hall currents flowing equatorward in the high conductivity channel.     

Magneto-convection in sunspot penumbrae

Finite amplitude convection in the presence of a horizontal magnetic field has been investigated in a region where thermal diffusivity (κ) is less than magnetic diffusivity (η) and whenκ/η > 1,Q ≤Q _c, where $$Q_c = \frac{{(1 + \sigma _1 )(\pi ^2 + q_c^2 )^2 }}{{q_c^2 (\sigma _2 - \sigma _1 )}}$$ ,Q is the Chandrasekhar number,σ ₁ the Prandtl number,σ ₂ the magnetic Prandtl number, andq _c the critical wave number at the onset of stationary convection. We have derived a nonlinear time-dependent Landau—Ginzburg equation near the onset of supercritical stationary convection and a nonlinear, second-order equation at the Takens—Bogdanov bifurcation. We have obtained steady-state solutions of these equations, which describe the nonlinear behaviour near the onset of stationary convection.     

The roles of the north-south component of the interplanetary magnetic field on large-scale auroral dynamics observed by the DMSP satellite

An extensive study of DMSP photographs and the simultaneous interplanetary magnetic field data suggests that the quantity defined by

$\text{S=∫}{}^{\mathrm{\tau }}{}_0\text{(Ф}{}_{\mathrm{D}}\text{? Ф}{}_{\mathrm{N}}\text{)dt}$

has a fundamental importance in substorm processes, where Φ_D and Φ_N denote the production rate of merged (or open) field lines along the dayside X-line and of reconnected (or closed) field lines along the nightside X-line, respectively; t = 0 is measured from the time when the B_z component begins to decrease after a prolonged period of a large positive B_z value. It is shown, first of all, that substorms occur so long as S > 0, regardless of the sign of the B_z component and its changes (namely, the southward and northward turnings) and of its time derivative as well. Secondly, the intensity of substorms is proportional to S². By introducing the quantity S, the recent confusion of the problem of the roles of the north-south component of the interplanetary magnetic field on substorm processes can be removed.Since S is equal to the amount of the open magnetic fluxes at a time reckoned from t = 0, it is proportional to (A₁ ? A₀), where A₀ denotes the minimum polar cap area (namely, the area bounded by the minimum auroral oval) and A₁ the polar cap area at an arbitrary time t. Therefore, substorms can occur whenever the auroral oval is larger than its minimum size. Further, an intense substorm tends to occur along a large oval.The quantity S can also be considered as an excess flux, and thus the substorm can be considered as a process by which the magnetosphere tends to remove sporadically the excess energy associated with S.     

Saturn's magnetospheric interaction with Titan as defined by Cassini encounters T9 and T18: New results

We present new results of Cassini's T9 flyby with complementary observations from T18. Based on Cassini plasma spectrometer (CAPS) and Cassini magnetometer (MAG), compositional evidence shows the upstream flow for both T9 and T18 appears composed of light ions (H⁺ and H₂⁺), with external pressures ∼30 times lower than that for the earlier TA flyby where heavy ions dominated the magnetospheric plasma. When describing the plasma heating and sputtering of Titan's atmosphere, T9 and T18 can be considered interactions of low magnetospheric energy input. On the other hand, T5, when heavy ion fluxes are observed to be higher than typical (i.e., TA), represents the limiting case of high magnetospheric energy input to Titan's upper atmosphere. Anisotropy estimates of the upstream flow are 1<T_⊥/T_‖<3 and the flow is perpendicular to B, indicative of local picked up ions from Titan's H and H₂ coronae extending to Titan's Hill sphere radius. Beyond this distance the corona forms a neutral torus that surrounds Saturn. The T9 flyby unexpectedly resulted in observation of two “wake” crossings referred to as Events 1 and 2. Event 2 was evidently caused by draped magnetosphere field lines, which are scavenging pickup ions from Titan's induced magnetopause boundary with outward flux ∼2×10⁶ ions/cm²/s. The composition of this out flow is dominated by H₂⁺ and H⁺ ions. Ionospheric flow away from Titan with ion flux ∼7×10⁶ ion/cm²/s is observed for Event 1. In between Events 1 and 2 are high energy field aligned flows of magnetosphere protons that may have been accelerated by the convective electric field across Titan's topside ionosphere. T18 observations are much closer to Titan than T9, allowing one to probe this type of interaction down to altitudes ∼950 km. Comparisons with previously reported hybrid simulations are made.     

Spatial distribution and kinematics of OB stars

The sample of 37 485 suspected OB stars selected by Gontcharov (2008) from the Tycho-2 catalogue has been cleaned of the stars that are not of spectral types OV-A0V. For this purpose, the apparent magnitude V _T from Tycho-2, the absolute magnitude $M_{V_T }$ calibrated as a function of the dereddened color index (B _T ? V _T )₀, the interstellar extinction $A_{V_T }$ calculated from the 3D analytical model by Gontcharov (2009) as a function of the Galactic coordinates, and the photometric distance r _ph calculated as a function of V _T , $M_{V_T }$ , and $A_{V_T }$ have been reconciled in an iterative process. The 20 514 stars that passed the iterations have (B _T ? V _T )₀ < 0 and $M_{V_T }$ > ?5 and are considered as a sample of OV-A0V stars complete within 350 pc of the Sun. Based on the theoretical relation between the dereddened color and age of the stars, the derived sample has been divided into three subsamples: (B _T ? V _T )₀ < ?0.2, ?0.2 < (B _T ? V _T )₀ < ?0.1, and ?0.1 < (B _T ? V _T )₀ < 0, younger than 100, 100?C200, and 200?C400 Myr, respectively. The spatial distribution of all 20 514 stars and the kinematics analyzed for more than 1500 stars with radial velocities from the PCRV and RAVE catalogues are different for the subsamples, showing smooth rotations, shears, and deformations of the layer of gas producing stars with the formation of the Gould Belt, the Great Tunnel, the Local Bubble, and other structures within the last 200 Myr. The detected temporal variations of the velocity dispersions, solar motion components, Ogorodnikov-Milne model parameters, and Oort constants are significant, agree with the results of other authors, and show that it is meaningless to calculate the kinematic parameters for samples of stars with uncertain ages or with a wide range of ages.