Total electron content of the ionosphere at 31°S, 1967–1974

The total electron content (TEC) of the ionosphere at 31°S (geographic) has been calculated on the basis of Faraday rotation measurements made between September 1967 and January 1975 using geostationary satellites. The day-to-day, diurnal, seasonal and solar cycle variations of TEC are illustrated and discussed in relation to the maximum electron density of the F-layer, NMAX. A regression analysis is used to derive curves corresponding to fixed high and low levels of activity. The variations of slab thickness S = TEC/NMAX are also illustrated and discussed. The results overlap the observation periods of other published results and general agreement is found with these other results.     

Climatologies of semi-diurnal and diurnal tides in the middle atmosphere (70–110 km) at middle latitudes (40–55°)

The radars utilized are meteor (2), medium-frequency (2) and the new low-frequency (1) systems: analysis techniques have been exhaustively studied internally and comparatively and are not thought to affect the results. Emphasis is placed upon the new height-time contours of 24, 12 h tidal amplitudes and phases which best display height and seasonal structures; where possible high resolution (10 d) is used (Saskatoon) but all stations provide monthly mean resolution. At these latitudes the semi-diurnal tide is generally larger than the diurnal (10–30 m s⁻¹ vs. < 10 ms⁻¹), and displays less month to month variability. The semi-diurnal tide does show significant regular seasonal structure; wavelengths are generally small (⩽50 km) in winter, large in summer (≲ 100 km), and these states are separated by rapid equinoctial transitions. There is some evidence for less regularity toward 40°C. Coupling with mean winds is apparent. The diurnal tide has weaker seasonal variations; however there is a tendency for vertical wavelengths and amplitudes to be larger during summer months. On occasions in winter and fall wavelengths may be less than 50 km. Again the seasonal transitions are in phase with reversals of the zonal wind. Agreement with new numerical models is to be shown encouraging.     

Tides in the 80–100 km height region

The Institute of Experimental Meteorology (U.S.S.R.) has carried out long-term continuous wind velocity measurements by the meteor radar method for the 80–100 km height region. From this experimental data the seasonal and latitudinal variations of atmospheric tides, as well as the spatial and temporal scales of tidal variability, have been determined.Atmospheric variations with a period of about half-a-day are investigated on the basis of a numerical model. A dependence between the mean wind structure and the semi-diurnal oscillation in the lower thermosphere is established. The influence of stratospheric warmings on semi-diurnal oscillations is also discussed. Numerical experiments show that the mean wind variations cannot explain the observed seasonal variations of a semi-diurnal tide.     

The dynamics of ion layer generation in the 80–150 km altitude region at low and mid-latitudes

The association of sporadic ion and sporadic sodium layers in the low-latitude, 90–100 km altitude region suggests that we must look beyond the windshear theory for details of the formation mechanism of sporadic layers in the 80–150 km altitude region. We present evidence, including specific 85–105 km results from the AIDA-89 and the ALOHA-90 campaigns, that 80–150 km altitude sporadic layers—including sporadic sodium layers—are generated in a complex interplay of tidal and acoustic-gravity wave (AGW) dynamics with temperature-dependent chemistry where wave-produced temperature variations are both adiabatic and dissipative or turbulent (non-reversible) in origin. We suggest that layering processes are best studied with an instrument cluster that includes sodium and iron lidars, MST radar (turbulence), incoherent scatter radar (electron concentration and winds), meteor radar techniques (winds), passive optical/IR imaging techniques, and appropriate rocket payloads to study a significant volume of the 80–150 km altitude region. We introduce the concept of volumtric radar and lidar techniques.     

A numerical study of the lunar tide in the mid-latitude F2-region of the ionosphere—I. Oscillations of the electron density

The continuity equations for four ion species and the momentum equations for the ion, electron and neutral gases are solved numerically. The momentum equations for ions and electrons include the effects of the electric field, and that for the neutral gas includes the effects of the collision between ions and neutrals, Coriolis force, the viscosity and the horizontal pressure force. It is found that the calculated semi-monthly tidal oscillations in NmF2 during the day and night-time are almost out of phase to each other, while the phase of the oscillations in hmF2 is weakly dependent on the solar time. The amplitude and phase of the calculated semi-diurnal lunar tide averaged over the solar times are 1.7% and 9.1 h (in NmF2) and 4.6 km and 8.1'h (in hmF2) respectively, at 45.0° dip. The height distribution of the semi-monthly lunar tide in the electron density is also obtained. The results show that the phase is 2 h for the lower region (below 200 km) and shifts to 9 h above about 250 km in the daytime, whereas it is nearly constant with height in the night-time. The calculated results are in good agreement with observations except for the phase at night. Thus it may be concluded that the major features of the observed lunar tidal variations in the mid-latitude F2-region can be explained by the electromagnetic drifts due to the solar and lunar electric fields.     

The seasonal variations in the nighttime 6300 Å emission at midlatitudes from ISIS-II spacecraft

Optical limb observations at F-region heights from the ISIS-II satellite have been used to study the seasonal variations in the 6300 Å limb emission for nighttime conditions and the aeronomic implications. The observations were carried out over the American zone at northern midlatitudes, and refer mainly to the period 1973–1975 of low solar activity.The observed seasonal variations in the emission seem to be mainly controlled by the electron density at F-region heights for nighttime and quiet geomagnetic conditions. The winter minimum is found to be deeper than the summer minimum. The obervations give clear evidence of semiannual variation in the emission. The phase variations agree closely with that of the semiannual variations in electron density and neutral atmospheric density at F-region heights. However, the amplitude variations of the semiannual variations are found to be larger than suggested by the observed F-region electron density. The observations during highly disturbed conditions possibly show the presence of gravity waves with wavelengths around 500 km, which could transport auroral energy to lower latitudes. The midlatitude enhancements observed during disturbed conditions seem to be related to the inward movement of the plasmapause.     

Wind corners in the 70–100 km altitude range as observed at andenes (69° latitude)

In the altitude range 70–100 km, high-resolution wind profiles have been measured during the summers of 1987 and 1988 at Andenes (69°N). We report on the wind corners observed in these profiles and compare their properties with those of wind corners seen in the winter of 1983–1984 and autumn 1987. Five of the main results are as follows. (1) The occurrence rates for wind corners in general are similar in summer and in winter. The database for autumn (only 7 flights) was too small to draw any firm conclusions. A strong wind corner was seen, roughly, on every third experiment, both in summer and in winter. (2) The results obtained on the temporal occurrence of wind corners suggest that wind corners seem to have no preference to appear at certain hours of the day. (3) Wind corners tend to appear at preferred heights which are higher in summer than in winter. The spacing between these preferred heights is about 5 km in summer and about 3-3.5 km in winter. (4) In strong wind corners the sense of rotation of the wind direction is positive in summer and negative in winter (with positive being defined as a rotation of the wind direction from northward towards eastward with increasing altitude). (5) At altitudes below 90km wind corners tend to occur at or close to atmospheric layers having Ri ≈ 0.25.     

Radio wave turbulent ‘absorption’ due to electron beam injections in the ionosphere

Considered is the collisionless damping of high-frequency radio waves in the ionospheric plasma perturbed by electron beams. Special attention is paid to the attenuation of telemetric signals, observed in the ARAKS experiment with intense electron beam injections, and to the ‘spike’ ionospheric absorption events. It is shown that these phenomena may be explained in terms of the nonlinear scattering of radio waves by plasma turbulence driven by electron beams and accompanied field-aligned currents.     

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.     

Response of the outer ionosphere to the magnetic storm of 20–22 March 1990

Measurements of the thermal plasma parameters in the interval 17–23 March 1990, made within the scope of the ACTIVE Project, were analysed to study the response of the outer ionosphere to the storm with SSC at 22.45 UT on 20 March. These measurements in the morning sector at altitudes around 2000 km clearly reflect the enhanced geomagnetic activity. They allow us to estimate the radial depth to which the plasmasphere has been affected by increased magnetospheric convection and at which a new equatorial plasmapause has formed. They also provide the possibility of monitoring the initial phase of recovery.The measurements in the dusk altitudes of 500–1000 km indicate a distincttrough in electron concentration and also a trough of light ions under relatively quiet, as well as under disturbed, conditions. The position of the equatorial edge of these troughs and the position of electron temperature peaks enable us to judge whether a plasmaspheric bulge has formed, and whether an inner plasmapause exists.     

Mean winds at 60–90 km observed with the MU radar (35°N)

Mean winds at 60–90 km altitudes observed with the MU radar (35°N, 136°E) in 1985–1989 are presented in this paper. The zonal wind at 70 km became westward and eastward in summer and winter, respectively, with a maximum amplitude of 45 m s⁻¹ westward in early July and 80 m s⁻¹ eastward at the end of November. The meridional wind below 85 km was generally northward with the amplitudes less than 10 m s⁻¹. In September to November, the meridional wind at 75–80 km becomes as large as 20–30 m s⁻¹. Those zonal wind profiles below 90 km show good coincidence with the CIRA 1986 model, except for the latter half of winter, from January to March, when the observational result showed a much weaker eastward wind than the CIRA model. The height of the reversal of the summer wind from westward to eastward was determined as being 83–84 km, which is close to the CIRA 1986 model of 85 km. The difference between the previous meteor radar results at 35–40°N, which showed the reversal height below 80 km, could be due to interannual variations or the difference in wind measurement technique. In order to clarify that point, careful comparative observations would be necessary. These mean winds were compared with Adelaide MF radar observations, and showed good symmetry between the hemispheres, including the summer reversal height, except for the short period of eastward winds above Kyoto and the long period over Adelaide.     

The role of the AALD in preserving the Australia–US alliance

This article critically evaluates the agenda and strategy of the Australian American Leadership Dialogue (AALD) for protecting and strengthening the Australia–US alliance. Nominally an exercise in informal diplomacy dedicated to fostering mutual understanding, the AALD functions more like a pro-American lobby group as it seeks to preserve orthodox thinking and eschew dissenting perspectives. The AALD performs this function in three main ways: by carefully framing discussion and debate, by socialising Australian elites into the alliance orthodoxy and by serving as a ‘gatekeeper’ of the status quo.

本文对保卫、加强澳美联盟的澳美领袖对话提出批评。该对话虽然名义上只是加强共同理解的非正式外交实践, 但其作用更像是亲美游说集团,因为它要保持正统的思路,回避不同的观点。该对话用三种方式实现这一功能：小心地设置讨论和辩论;向澳大利亚精英灌输联盟的正统观;充当现状的守门人。     

The Excavations at Stična in Slovenia by the Duchess of Mecklenburg, 1905–1914

Abstract

Museum collections of documented but unpublished archaeological material often constitute excellent sources of primary archaeological data. The Duchess of Mecklenburg excavated extensively at Iron Age cemeteries in Slovenia, in what is now part of Yugoslavia, just before the First World War. Her collection, which is now being published, provides hundreds of well-documented grave groups for study. This article considers her work at the site of Sti?na and is concerned particularly with the graves containing weapons excavated at that site.     

The idea of peace in the West, 500–1150

Most of the numerous peace traditions of the early middle ages developed within a framework of three dimensions: monastic, ecclesiastical, imperial. But after 1150 the equilibrium among these three views of peace became upset. The pax ecclesiae and the imperial peace were channeled into papal jurisdiction and the public peace of the lay powers. The monastic peace began to lose its influence upon society at large.     

The scientific commons in the marketplace: the industrialization of biomedical materials at the New England Enzyme Center, 1963–1980

This paper investigates the industrialization of biomedical materials at the New England Enzyme Center (NEEC) from its establishment as a federally supported biochemical resource center in 1964 through its demise and refashioning into several commercial biotech companies in the late 1970s. It sets this history within the long‐standing debate on the proper relation between science and American economic and political traditions. The NEEC sought to embody two aims that stood in tension: academic independence in knowledge production and the market‐driven interests of the biomedical industry. A clash of values ensued, but built on a particular notion of independence: scientists pragmatically accepted the primacy of the market in the age of the ‘federal research economy.’ The question became how to carve out a space for science and scientific values in the market – an intellectual position that some legal and economic scholars have referred to as a scientific commons. Even so, industry executives came to see the idea of a scientific commons and public knowledge as obstructive to industrial innovation. This paper argues that, as seen through the case of the NEEC, the ascendancy of market values and attitudes in the 1970s played a critical role in reconfiguring the science‐industry relationship and in ‘industrializing’ the life sciences. As illustration of this change, I look at a commercial firm – Genzyme – born out of NEEC’s dissolution.     

Parameterization of the radiative flux divergence in the 15 μm CO2 band in the 30–75 km layer

A parameterization of the cooling rate of the earth's middle atmosphere due to radiation transfer in the 15 μm CO₂ band is proposed. The parameterization has been performed for such an atmospheric layer with local thermodynamic equilibrium (below approximately 75 km), for which in the major part of the frequency interval occupied by the 15 μm band the approximation of non-overlapping lines (above about 30 km) is justified. The overlap of lines has only been taken account of for superposed strong Q-branches at the centre of the 15 μm band. The parameterization takes into account the peculiar features of radiation transfer:

• 1.(1) the height step increases with the growing distance from the level, for which cooling is calculated;
• 2.(2) the dependence of line intensity on temperature has partially been taken account of in an explicit form. The procedure proposed is multiparametric: 42 parameters are prescribed for calculating cooling at a given level. With an error less than 0.5 K day⁻¹ the procedure can be recommended for calculating radiative cooling in the case of any temperature profile undisturbed by small- and meso-scale motions and, in particular, for use in the modelling of the middle atmospheric circulation.