The amplitude of auroral backscatter—I. Model estimates of the dependence on electron density

A model of the auroral backscatter amplitude, in the form discussed by Uspensky and Oksman et al., has been derived for the radar geometry appropriate to joint observations by the PGI auroral radars at Karmaselga and Essoyla and the EISCAT incoherent scatter radar. The model shows how refraction effects cause a strongly non-linear dependence of backscatter amplitude on electron density in the E-region. It also explains why the macro aspect sensitivity for auroral radar operating at a frequency of about 45 MHz is only 1–2 dB per degree for aspect angles greater than 5°.     

Meteorological effects in the variations of ionospheric parameters—I. The lower thermosphere

The influence of the troposphere and stratosphere on variations of ionospheric D-region parameters are discussed. It is found that variations of the minimum observable ionosonde frequency (f_min) and horizontal winds are closely related to temperature and pressure fields in the lower atmosphere. Experimental data for the Central Asian and East Siberian U.S.S.R. regions have been used.     

Geomagnetically quiet day ionospheric currents over the Indian sector—III. Counter equatorial electrojet currents

Counter equatorial electrojet (CEJ) occurring at all hours from 0700 to 1700 h LT in the Indian sector have been studied. The percentage occurrence of morning and afternoon CEJ in each hour and each season are given and discussed. The first quantitative determinations of eight landmark parameters that depict the structures of hourly latitudinal profiles of CEJ current have been presented and discussed.These are the peak height integrated forward current density (or intensity) at the centre of the current, the peak return current intensity, the ratio of the peak return to the peak forward current intensity, the total forward current, the dip latitude of the current centre, the distance of the focus from the current centre, the distance of the peak return current intensity from the centre, and the latitudinal extent of the current. They reveal new and interesting features of diurnal and seasonal variations, and marked contrasts between morning and afternoon CEJ. Other evidences support our focal distance w of CEJ. Comparison with equatorial electrojet (EEJ) shows that five of the parameters are similar for EEJ and morning CEJ but substantially different for afternoon CEJ. The counter worldwide part of Sq currents have also been compared with CEJ.     

Effects of ionospheric irregularities on radio waves—II. Group path changes

The effects of ionospheric irregularities on the group path of radio waves reflected at vertical incidence are studied using model irregularities. The basic approach used is quite general in that irregularities and background ionospheres of arbitrary shape may be considered. The method is demonstrated by the use of simple triangular shaped irregularities. For the ionospheric conditions considered irregularities below X ∼ 0.85 have relatively little effect on the group path of ordinary rays. Irregularities extending above this level produce large effects partially due to the rapid variation of the group refractive index near reflection. High gradients produced by irregularities, particularly near reflection, can also be regarded as causing large group path effects. The effect of irregularities near the reflection level is not as dramatic in the extraordinary ray case because the refractive index does not change as rapidly near reflection as it does in the ordinary ray case. When the reflection height is changed by the irregularity the situation is complex because different effects produce opposing changes in the group path. The result is that an irregularity of a given percentage increase in intensity has a maximum positive effect on the group path when it is positioned so that it extends up to reflection without causing reflection height variations. Its maximum negative effect occurs when maximum reflection height lowering takes place. The group path change produced by an irregularity is dependent on irregularity intensity, thickness and background gradient but is least sensitive to intensity. This is in contrast to the phase path changes which are very dependent on background gradient and irregularity intensity but not on thickness. Possible applications of the results to swept frequency group path experiments are discussed and some examples are given.     

Legends of the Lincolnshire Cars.—Part III

PREHISTORIC MAN IN IRELAND. By CECIL P. MARTIN. London : Macmillan, 1935. Pp. xi, 184. Price, 21s. Reviewed by G. M. Morant.

ANNUAL CUSTOMS AND FESTIVALS IN PEKING, AS RECORDED IN THE YEN-CHING SUI-SHIH CHI BY TUN LI-CH'EN. Translated and annotated by DERK BODDE. Peiping. Henri Vetch. Pp. xxii + 147. 9½ × 6½. 13s. 6d. Reviewed by A. Waley.

THE HERO : A STUDY IN TRADITION, MYTH AND DRAMA. By LORD RAGLAN. London: Methuen &; Co., Ltd. 1936. 8¾ × 5½. Price 10s. 6d. net. Reviewed by Warren R. Dawson.

L'ILE DE PAQUES ET SES MYSTÈRES. By DR. STEPHEN-CHAUVET. Aux Éditions “Tel”,. Paris. 1935. 12″ × 9½. Pp. 88, Plates lxvii + pp. [8]. 70 francs (deluxe edition, 85 francs). Reviewed by Alan S. C. Rosa.

CUSTOM IS KING. Essays presented to R. R. Marett on his seventieth birthday, June 13th, 1936. Edited by L. H. DUDLEY BUXTON. Hutchinson. 12s. 6d. net Reviewed by E. O. James.

HILMA GRANQVIST, Ph.D. : MARRIAGE CONDITIONS IN A PALESTINIAN VILLAGE, II. In Societas Scientiarum Fennica. Commentationes Humanarum Litterarum, VI, 8. Helsingfors, 1935, 366 pp. Reviewed by M. Gaster.

DON GYPSY. ADVENTURES WITH A FIDDLE IN BARBARY, ANDALUSIA AND LA MANCHA. By WALTER STARKIE, Litt.D. London : John Murray. Pp. 498. 10s. 6d. and 5s. Reviewed by Rodney Gallop.     

A numerical model of the ionospheric dynamo—III electric current at equatorial and low latitudes

Using the general dynamo model and its special cases derived in a previous paper, the distributions of three dimensional electric current density in a magnetic meridional plane in the equatorial and low latitude ionosphere are computed. The winds generating the ionospheric dynamo are tide-like and locally periodic, similar to those in an internal gravity wave. Very large (several μA m⁻²) field-aligned current density is obtained in the equatorial region at places of sharp vertical gradients of the wind velocity. The currents generated by locally periodic winds of latitudinal wavelength less than several hundred kilometers do not significantly affect the normal equatorial electrojet.     

A numerical model of the ionospheric dynamo—I. Formulation and numerical technique

A new method of numerically solving a suitably formulated ionospheric wind dynamo equation for electrostatic potential and field is developed. Unlike in many other dynamo models, the upper boundary does not exist and the formulation asymptotically approaches the equatorial boundary condition. Therefore, it naturally incorporates the symmetric, asymmetric E- and F-region dynamo actions in any given ionosphere and any given global or local wind field. It also enables the equation to be posed as an initial value problem and solved numerically using an efficient, accurate, stable and fast integration method of ordinary differential equations. The numerical technique can be extended to compute three dimensional dynamo-generated electric currents in the ionosphere.     

The winter anomaly in the ionospheric D-region—some numerical calculations

This paper reports on results of numerical calculations for conditions under which the anomalously high absorption of radio waves appears and disappears at middle atmosphere heights, having characteristic time constants of about 24 h. In the calculations we have solved a system of equations which are self-consistent in a one-dimensional approximation and govern the temperature and neutral and ion composition behaviour in the height range 40–150 km. The values of the turbulent transfer coefficient and turbulent energy dissipation rate were calculated for the case of the anomalous absorption commencement, using experimental data pertaining to the vertical structure of the wind and temperature field. The results derived from numerical calculations involving evidence of turbulent processes were used to interpret some characteristic properties of neutral and charged particles, temperature and densities for day-time conditions with anomalously high absorption. The lack of experimental data on winds and temperature throughout the height range under study for the dates with normal absorption forced us to use indirect measurements in making assumptions about the vertical profile of the turbulent transfer coefficient and the values of the turbulent dissipation rate. The results thus obtained agree with measurements of electron density, temperature and hydroxyl emission intensity (the hydrogen content decreases as the conditions change from anomalous to normal). There are, however, discrepancies between calculated and measured atomic oxygen densities.     

Introduction to ionospheric heating at Tromsø—I. Experimental overview

The HF ionospheric modification (heating) facility at Ramfjordmoen will become a part of the EISCAT association from January 1993. This paper, which is intended for the new user, describes the technical capabilities of the facility and the broad range of geophysical and plasma physical experiments which are possible. An overview is presented of the physical effects that a powerful HF electromagnetic wave incident on the ionosphere can produce on timescales ranging from tens of microseconds to minutes in height regions ranging from 50 to hundreds of km. Emphasis is placed on the practical implementation of ionospheric heating experiments using the EISCAT incoherent scatter radars as the main diagnostic, but other diagnostic techniques using ground-based radars, radio links, radio receivers, photometers, rocket and satellite instrumentation are also described. A companion paper presents in greater depth some of the current scientific issues being addressed in ionospheric modification research.     

Introduction to ionospheric heating experiments at Tromsø—II. Scientific problems

In the first section the theory of parametric decay instabilities (PDI) is briefly described. Then results of joint heating/incoherent scatter observations at Tromsø are presented. It turns out that most of the observed features are in good agreement with that theory, while some others remain still unexplained. Among the latter features the most striking is the existence of a ‘space-time blob structure’, which means that the time variation of scattered power from adjacent altitudes seems to be correlated. Experiments at Arecibo often lead to results different from ours. Some scientists in the field explain these observations in terms of a ‘strong turbulence’ in which also caviton formation is involved. We think that most of the Tromsø results can be adequately explained by the parametric decay process.     

The breakdown of the educational system of the G.D.R. in 1989—Problems of restructuring public education

The disappearance of an apparently well-established European state within one year—sudden, unexpected, and self-imposed—probably presents an event without parallels in European history. In educational history, too, there may be few examples of bringing together the structures of two very different educational systems after four decades of separate development.     

The print depiction of King William III’s masculinity

This article examines both positive and negative print depictions of King William III, specifically how William’s masculine identity was produced and perceived in relation to readily accessible norms of manhood. That commentators invoked discourses of masculinity to both legitimate and denounce William’s regime suggests the importance of masculinity to kingly meaning. By discussing the ways in which William does or does not conform to gender ideals, commentators reveal that, although freighted differently, normative models of kingship and masculinity shared common expectations and overlapped in easily recognisable ways. As his critics reminded, William III neither achieved the supposed “hegemonic” patriarchal form of masculinity nor that of the ideal monarch because he remained childless. As such, William’s print portrayal sheds light on codes of masculinity in early modern Britain that were constructed in a variety of settings outside of the problematic paragon of patriarchal manhood.