Thermal balance of the mid-latitude F2-region at night     

G.J. Bailey  R.I. Footitt  R.I. Moffett 《Planetary and Space Science》1979,27(8):1063-1073

The thermal balance of the plasma in the night-time mid-latitude F2-region is examined using solutions of the steady-state O⁺ and electron heat balance equations. The required concentrations and field-aligned velocities are obtained from a simultaneous solution of the time-dependent O⁺ continuity and momentum equations.The results demonstrate the systematic trend for the O⁺ temperature to be 10–20 K greater than the electron temperature during the night at around 300 km, as observed at St. Santin by Bauer and Mazaudier. It is shown that frictional heating between the O⁺ and neutral gases is the cause of the O⁺ temperature being greater than the electron temperature; the greater the importance of frictional heating in the thermal balance the greater is the difference in the O⁺ and electron temperatures. A study is made of the roles played in the thermal balance of the plasma by the thermal conductivity of the O⁺ and electron gases; collisional heat transfer between O⁺ electrons and neutrals; frictional heating between the O⁺ and neutral gases; and advection and convection due to field-aligned O⁺ and electron motions. The results of the study show that, at around 300 km, electron cooling by excitation of the fine structure of the ground state of atomic oxygen plays a major role in the thermal balance of the electrons and, since the temperature of the ions is little affected by this electron cooling process, in determining the difference between the ion and electron temperatures.  相似文献   

Some comments on the Oort cloud     

M. E. Bailey 《Astrophysics and Space Science》1977,50(1):3-22

The arguments used by Lyttleton to prove the nonexistence of the Oort cloud are reviewed, and it is shown that Oort's hypothesis remains consistent with observation. The 1950 model of the cloud cannot be correct and, by use of the results from a number of more recent papers, an improved model is described and compared with observations. It is emphasized that comparison of the predictions of theory with observations should concentrate on thea-distribution, as the 1/a-distribution masks much of the detailed structure of the theory. An order of magnitude argument is given which shows that 20% of so-called new comets have passed through the planetary system before, and the implications of this to the statistics of near-parabolic comet orbits are briefly investigated.  相似文献   

Relative flow of H⁺ and O⁺ ions in the topside ionosphere at mid-latitudes     

G.I. Bailey  R.J. Moffett  J.A. Murphy 《Planetary and Space Science》1977,25(10):967-972

Theoretical results on the daily variation of O⁺ and H⁺ field-aligned velocities in the topside ionosphere are presented. The results are for an L = 3 magnetic field tube under sunspot minimum conditions at equinox. They come from calculations of time-dependent O⁺ and H⁺ continuity and momentum balance in a magnetic field tube which extends from the lower F2 region to the equatorial plane (Murphy et al., 1976).There are occasions when ion counterstreaming occurs, with the O⁺ velocity upward and H⁺ velocity downward. The conditions causing this counterstreaming are described: the H⁺ layer is descending whilst O⁺ is supplied from below either to increase the O⁺ concentration at fixed heights or to replace O⁺ ions lost by charge exchange with neutral H. It is suggested that the results of observations at Arecibo by Vickrey et al. (1976) of O⁺ and H⁺ concentrations and counterstreaming velocities are significantly affected by $\text{E}\text{×}\text{B}$ drift.  相似文献   

Reply to the comment by Addo Van Pul and John H. Van Boxel on ‘a first order closure scheme to describe counter gradient momentum transport in plant canopies’ by Li,Miller and Lin     

W. Bailey 《Boundary-Layer Meteorology》1990,51(3):317-317

Correspondence

Reply to the comment by Addo Van Pul and John H. Van Boxel on a first order closure scheme to describe counter gradient momentum transport in plant canopies by Li, Miller and Lin  相似文献   

Interhemispheric flow of thermal plasma in a closed magnetic flux tube at mid-latitudes under sunspot minimum conditions     

G.J. Bailey  R.J. Moffett  J.A. Murphy 《Planetary and Space Science》1978,26(8):753-765

The coupled H⁺ and O⁺ time-dependent continuity and momentum equations are solved within a region of the L = 3 magnetic flux tube lying between (and including) the F2-layers of conjugate hemispheres. The method of solution is an extended and modified version of the Murphy et al. (1976) method. The model is used to study the coupling between the F2-layers of conjugate hemispheres during magnetically quiet periods.The results of the calculations strongly indicate that the protonosphere acts as a reservoir, with variable H⁺ content, which prevents direct coupling between the F2-layers of conjugate hemispheres. However there is generally a significant interhemispheric flow of plasma. This flow is caused by conditions in the summer and winter topside ionospheres and it maintains continuity in the plasma concentration within the protonosphere. There are times when the direction of flow is from the winter hemisphere to the summer hemisphere. It is suggested that maintenance of the winter F2-layer at night is not assisted directly by the F2-layer of the conjugate summer hemisphere.It is shown that during the first few days of protonosphere replenishment after a magnetic storm there is an upflow of H⁺ in the topside ionosphere at all times in the summer hemisphere. There is also an upflow of H⁺ during the daytime in both hemispheres. A comparison with the results obtained when the interhemispheric H⁺ flux is held permanently at zero shows that both F2-layers are little affected by the interhemispheric H⁺ flux. Nevertheless both F2-layers are affected by the H⁺ tube content of the protonosphere. When the H⁺ flux at 1000 km in one hemisphere is much greater than the H⁺ flux at 1000 km in the conjugate hemisphere, there is a corresponding signature in the interhemispheric H⁺ flux.The results suggest that there is insufficient time between magnetic storms for complete replenishment of the protonosphere to occur.  相似文献   

Application of the QUILF thermobarometer to the peralkaline trachytes and pantellerites of the Eburru volcanic complex, East African Rift, Kenya   总被引：1，自引：0，他引：1  

Minghua Ren  Peter A. Omenda  Elizabeth Y. Anthony  John C. White  Ray Macdonald  D.K. Bailey   《Lithos》2006,91(1-4):109-124

The Quaternary Eburru volcanic complex in the south-central Kenya Rift consists of pantelleritic trachytes and pantellerites. The phenocryst assemblage in the trachytes is sanidine + fayalite + ferrohedenbergite + aenigmatite ± quartz ± ilmenite ± magnetite ± pyrrhotite ± pyrite. In the pantellerites, the assemblage is sanidine + quartz + ferrohedenbergite + fayalite + aenigmatite + ferrorichterite + pyrrhotite ± apatite, although fayalite, ferrohedenbergite and ilmenite are absent from more evolved rocks (e.g. with SiO₂ > 71%). QUILF temperature calculations for the trachytes range from 709 to 793 °C and for the pantellerites 668–708 °C, the latter temperatures being among the lowest recorded for peralkaline silicic magmas. The QUILF thermobarometer demonstrates that the Eburru magmas crystallized at relatively low oxidation states (ΔFMQ + 0.5 to − 1.6) for both trachytes and pantellerites. The trachytes and pantellerites evolved along separate liquid lines of descent, the trachytes possibly deriving from a more mafic parent by fractional crystallization and the pantellerites from extreme fractionation of comenditic magmas.  相似文献   

Bringing NEOs into focus     

Duncan Steel  Mark Bailey 《Astronomy& Geophysics》2002,43(1):1.14-1.15

Duncan Steel and Mark Bailey report on the well-attended December 2001 G Discussion Meeting whose subject was near-Earth objects.  相似文献   

Comet Ikeya-Zhang rises for the NAM     

David Asher  Mark Bailey  Apostolos Christou  John McFarland  Mark Muir  Paul Rafferty 《Astronomy& Geophysics》2002,43(2):2.19-2.21

A possible naked-eye comet that may have been important in early cometary theory is announced by D J Asher , M E Bailey , A Christou , J McFarland , M F Muir and P P Rafferty .
Early indications sugest that Comet C/2002 (Ikeya-Zhang), discovered on 1 February 2002, may brighten to naked-eye visibility in late March 2002. It has also been suggested that it may be identical to one of the brighter comets of the 16th or 17th centuries, namely C/1532 R1 or C/1661 C1. The first of these, observed for more than 100 days towards the end of 1532, played an important role in the development of cometary theory. The second, although identified by Halley as having an orbit similar to that of the comet C/1532 R1, was not seen on its predicted return in 1788/1789 and so was presumably unrelated. Here we present long-term orbital integrations of C/2002 C1 which suggest that it orginated from the Oort cloud, and will be ejected again, within ˜0.3 Myr. There is a chance of 10–20% that it will end its life by falling into the Sun during a Halley-type phase of cometary evolution. The discovery of Ikeya-Zhang so closeto perigee by two amateur astonomers highlights the need for surveys covering both hemispheres to discover long-period and intermediate-period comets on Earth-crossing orbits.  相似文献   

Dublin days: the 2003 NAM     

Mark E Bailey  Tom Ray 《Astronomy& Geophysics》2003,44(3):3.07-3.08

Mark E Bailey and Tom Ray give an overview of the National Astronomy Meeting in Dublin, where record numbers of astronomers went to talk, listen and network.  相似文献   

An accurate and robust multigrid algorithm for 2D forward resistivity modelling   总被引：1，自引：0，他引：1  

Robert Moucha  Richard C. Bailey 《Geophysical Prospecting》2004,52(3):197-212

We present an adaptation of the full multigrid algorithm in DC resistivity modelling in an effort to increase its accuracy. There is a great difficulty with conventional multigrid solvers in representing the physics of an arbitrary distribution of electrical conductivity on a very coarse grid. In general, conventional rectangular finite‐difference or 5‐point approximations of Poisson's equation cannot represent, at a coarse grid level, the effective anisotropy on a coarse scale which results from fine structure in the model. An exception to this generalization occurs when the principal axes of structural anisotropy are aligned with the coordinate axis. Additional and similarly generated problems arise when a coarse cell is obliged to represent fine structure containing very high conductivity contrasts. We have developed an adaptation of the usual resistive‐network representation of the continuum, which avoids some of these problems, and have compared it with the traditional resistive network currently used. The network adaptation consists of replacing the usual 5‐point Laplacian operator stencil used on the finite‐difference grid with a 9‐point stencil, and the conductivity scalar with a 6‐parameter conductivity parametrization. This parametrization permits representation of arbitrarily orientated anisotropy as well as more complex behaviour related to high conductivity contrasts. The importance of multigrid solvers does not lie in their speed at forward modelling (which is comparable with other methods), but rather in their potential for inverse modelling. Inverse solvers which proceed by refinement of an initially very coarse solution can, in principle, take time only linearly proportional to the number of gridpoints in the final desired model.  相似文献