Modelling of complicated ionograms using several echoes

Simple structures are shown to be able to account for ionogram records supposed to be caused by the presence of horizontal stratifications in the ionosphere. Computer modelling has produced synthetic ionograms which appear similar to the real records, but based on the presence of several echoes, possibly due to small ripples in the ionospheric surface, as well as dispersion.     

The alliance echoes and portents of Australia's longest war

Afghanistan was Australia's longest war, yet the consensus between Australia's major political parties on the commitment never wavered over 12 years. The bipartisan unity held even as the nature of the war changed and evolved, Australian casualties rose and popular support fell away. The enduring centrality of the US alliance explains much—probably almost all you need to know—about the unbroken consensus of the Australian polity. Afghanistan was an example of the Australian alliance addiction, similar to Vietnam. As with Vietnam, the Australian military left Afghanistan believing it won its bit of the war, even if the Afghanistan war is judged a disaster. As Australia heads home it finds the USA pivoting in its direction; with all the similarities that can be drawn between Vietnam and Afghanistan, this post-war alliance effect is a huge difference between the two conflicts.     

High-energy electron drift echoes at the geostationary orbit

Approximately 60 high energy (0.7–2.6 MeV) electron drift echoes, observed with the UCSD omni-directional detectors on board ATS-5, have been analyzed. The period for longitudinal drift around the Earth is a function of energy and verifies the now classical law for relativistic electrons. Empirical relationships have been established, which statistically relate the characteristic period T₀ (the drift period for ~320 keV electrons) with the AE and Kp indices. These results are well interpreted if we adopt a Mead and Williams model (with special coefficients) for the magnetic field, and if we assume that the subsolar distance of the magnetopause R_b is mainly a function of Kp, the tail field B_T being mainly a function of AE. Evidence is given that these functional dependences agree with other experimental data, such as Coleman and McPherron's (1976) measurements of the midnight magnetic field intensity at the geostationary orbit. It is demonstrated that the origin of drift echoes is less likely to be an injection of high-energy particles, but more likely to be the consequence of a redistribution of particles among different L-shells after a sudden compression or expansion of the magnetosphere, as originally proposed by Breweret al. (1969).     

The use of the phasor display in studying ionospheric radio echoes

The phase and amplitude of a radio pulse reflected from the ionosphere usually vary during the pulse. It is convenient to observe these variations using the X-Y mode of an oscilloscope to display the phasor of the echo. The variations are then seen as an oval or spiral shape traced out by the end point of the phasor. These shapes provide a sensitive method of detecting the presence of more than one echo, and are useful as a measure of dispersion.     

A study of signal statistics of VHF radar echoes from clear air

Signal statistics of VHF radar returns from vertical pointing observations of the clear air are investigated. In particular, the signal signature, its Doppler spectrum and statistical distribution are examined. It is found that the most important factors that characterize the statistics of the signals are the width of the spectrum and the Nakagamim-coefficient for the intensity distribution. Using these factors as criteria, two types of signals are found. One corresponds to volume scattering arising from turbulence or multiple thin laminae or sheets. The other corresponds to return from a single sheet. Examples of the different scattering/reflection processes will be shown. Numerical modeling is used to simulate the scattering/reflection processes. From the simulation, it is demonstrated that echo signals from some range gates are consistent with the picture of reflection from a single, diffuse sheet, causing focusing and defocusing of the signals.     

The characteristics of VHF echoes from the summer mesopause region at mid-latitudes

Radar observations have been carried out at Aberystwyth (52.4°N, 4.1°W) during the period May–August 1990 to search for echoes analogous to the Polar Mesosphere Summer Echoes commonly observed at high latitudes. Signal strength measurements in the vertical and at 12° from the vertical are used to examine the aspect sensitivity of echoes, and Doppler measurements at 6° from the vertical and in the vertical to estimate wind velocities. The observations show the presence of two types of moderately strong echoes from heights above 80 km. On most days a spectrally broad echo is observed with characteristics consistent with isotropic turbulence scatter. On certain days between mid-June and mid-July, stronger spectrally narrow echoes are observed with characteristics similar to Polar Mesosphere Summer Echoes.     

On the relation between diffusion coefficients and height from radar meteor echoes

Diffusion coefficients derived from radar meteor echoes and corrected for atmospheric wind shears have been used to investigate a linear relation between diffusion and height in the atmosphere. The results of a least square fit and of a method in which both variables are considered subject to errors are presented and discussed. The present results seem to indicate that the relation between diffusion coefficient and height is not as simple as supposed. Scale height values derived from these data are not consistent with accepted values in the atmosphere.     

Answers and echoes: the Libellus responsionum and the hagiography of north-western European mission

This article examines three aspects of Augustine of Canterbury's Libellus responsionum. Through recent scholarship it provides a summary of the Libellus 's textual context. It also clarifies the very contentious issue of just how familiar the Libellus was to missionaries, not only those preaching in England but also on the Continent, and specifically Augustine of Canterbury and Boniface. Finally, in light of the pastoral and textual circumstances, it explores the largely neglected question of just how the Libellus may (or may not) have illuminated the various literary features and strata of Augustinian and Bonifatian biography.     

The characteristics of VHF radar echoes from the tropopause region near a jet stream

Measurements carried out with the SOUSY radar system to the south-east of a jet stream during a night in November 1981 are described. Particular attention is paid to the association between power and spectral width of echoes returned from the vicinity of the tropopause located near 12 km. A negative association is found between power and spectral width of echoes from 150 m height channels between 10.65 km and 11.70 km, both with the radar beam directed vertically and at 7° to the vertical in the northerly and easterly directions. Evidence for a positive association is only found for height channels centred at 11.85 and 12.15 km and then chiefly with the beam directed vertically. A partial correlation analysis suggests that the possible influences of the finite beamwidth of the radar system and of wind shear on the spectral width do not affect the associations found. The results are discussed in terms of the scattering and partial reflection mechanisms giving rise to the echoes.     

Moses' Cushite Wife echoes Hosea's Woman of Harlotries: Exposure of Unfaithfulness in the Wilderness

ABSTRACT

This paper suggests that Numbers 12 implies that the Cushite woman whom Moses marries is an immoral woman and that Moses' marriage with her is based on an implicit divine command which echoes the one God gives Hosea when exhorting him to marry a woman of harlotries. In both cases God wants the prophetic protagonist to experience infidelity, thus enabling him to experience what God feels like when Israel acts unfaithfully to Him. However, after experiencing the unfaithfulness of the Israelites in the narrative of the scouts Moses himself demonstrates unfaithfulness in Meribah. Moses' inability to respond appropriately to Israel's unfaithfulness at Baal-peor, an incident mentioned in Hos 9,10, reflects his inability to contend with the Israelites in the manner of Hosea.     

Observations of high latitude ionospheric conductances

A brief historical review of the development of models of the ionospheric conductivities with special emphasis on high latitude regions and the auroral zone is presented. It is with great admiration that we must conclude that the physical understanding of the importance of the ionospheric conductances was well perceived by pioneers like Schuster and Birkeland a hundred years ago. Progress in the basic theoretical fundamentals was achieved in the late 1920s and 1930s. Realistic estimates were not derived until the first rocket probes measured the electron and ion content at different altitudes in the 1950s.Today we have a superior technique in resolving electron density profiles of high time and height resolution by incoherent scatter radars on the ground. The challenge that we are facing is to obtain global conductivity maps, especially at high latitudes, with a time and spatial resolution which match the details in auroral substorm phenomena. If that can be achieved, great progress in the understanding of detailed dynamical coupling in the ionosphere, magnetosphere, and thermosphere systems is expected. The imaging technique as demonstrated by the DE-satellite can be the tool which eventually materializes our desires for increased knowledge.     

Observations on the China-Nepal Border

BACKGROUND:The China-Nepal border extends for 1400 kilometers with a total of 79 general markers and 98 border wood markers that are stretched over seven counties as well as the Ngari