User's guide for the Nimbus 7 ERB Solar Analysis Tape (ESAT)

Five years of Nimbus 7 ERB solar data is available in compact form on a single ERB solar analysis tape (ESAT). The period covered is November 16, 1978 through October 31, 1983. The Nimbus 7 satellite performs just under 14 orbits a day and the ERB solar telescope observe the Sun once per orbit as the satellite passes + or - near the south pole. The data were carefully calibrated and screened. Mean orbital and daily values are given for the total solar irradiance plus selected spectral intervals. In addition, selected solar activity indicators are on the tape. The ERB experiment, the solar data calibration and screening procedures, the solar activity indicators, and the tape format are described briefly

Regrowth-related defect formation and evolution in 1 MeV amorphized (001) Ge

Geimplanted with 1MeV Si⁺ at a dose of 1×10¹⁵cm⁻² creates a buried amorphous layer that, upon regrowth, exhibits several forms of defects–end-of-range (EOR), regrowth-related, and clamshell defects. Unlike Si, no planar {311} defects are observed. The minimal EOR defects are small dotlike defects and are very unstable, dissolving between 450 and 550°C. This is in contrast to Si, where the EOR defects are very stable. The amorphous layer results in both regrowth-related defects and clamshell defects, which were more stable than the EOR damage.This work is supported by Semiconductor Research Corporation Contract No. 00057787

Gravity Wave Ducting in the Upper Mesosphere and Lower Thermosphere Duct System

We report on a numerical study of gravity wave propagation in a pair of ducts located in a region where dramatic changes in the airglow most likely associated with ducted wave trains are observed. We examine ducting in an upper mesosphere inversion (INV) and an always present lower thermosphere stable layer (LTD) for a range of phase speeds and horizontal wavelengths characteristic of ducting events. We analyze the propagation and modal structure of ducted waves for backgrounds with increasing realism, starting with a climatological temperature profile where only the LTD is present. In succession, we add the INV based on the work of Smith et al. (2003), climatological winds, and winds in the upper mesosphere based on the work of Smith et al. (2003). We examine ducting for phase speeds between 40 and 100 m s¯¹ and horizontal wavelengths between 20 and 60 km. We find that without winds, only the LTD supports ducting of waves forced from below. When observed winds and temperatures are included, strong ducting is evident in both regions. For waves forced from below, the strongest ducted modes are those with slower phase speeds, and of these the third gravest agree reasonably well with the observed phase speeds and wavelengths, indicating that the observations are consistent with linear ducted waves. For waves forced in the INV, we find an intense and strongly dominant fundamental mode. This is a fast mode having phase speeds ~100 m s¯¹ for a horizontal wavelength of 30 km in the INV and much faster in the LTD. That the fundamental is not seen in Smith et al.’s (2003) observations indicates that the waves were forced from below and that the lowest mode was blocked by an evanescent barrier below the INV. Our results show that the two ducts communicate: the upward extensions of waves ducted in the INV are seen in the LTD. This is particularly significant in the case of in situ forcing, where the fundamentals combine to give amplification exceeding a factor of 10 in the LTD

Wave-modified Mean Exothermic Heating in the Mesopause Region

We employ a model of wave-driven OH nightglow fluctuations to calculate the effects of gravity waves on the chemical exothermic heating due to reactions involving odd hydrogen and odd oxygen species in the mesopause region. Using a model based on time means and deviations from those means, it is demonstrated that gravity waves contribute to the time-average exothermic heating. The effect can be significant because the fractional fluctuations in minor species density can be substantially greater than the fractional fluctuation of the major gas density. Our calculations reveal that the waves mitigate the exothermic heating, demonstrating their potential importance in the heat budget of the mesopause region

Shifting the paradigm on cultural property and heritage in international law and armed conflict: time to talk about reparations?

The demolition of the mausoleums in Timbuktu, the destruction of the Temple of Bel in Palmyra, and the aerial bombardment of the Old City of Sana’a in Yemen - each mark a continuing trend of intentionally targeting cultural property, and disregard for its protection under international humanitarian law. From as far back as records of war exist, through to contemporary conflicts, cultural sites have been a target for states and non-state armed groups. The destruction is used as a means to delegitimise opponents and displace their populations, reject the symbols of a regime, disrupt a sense of continuity for communities and corrode collective identities. (Brosché et al. 2017 & Ascherson 2005) While international law has focused on a three-P approach (hereafter ‘PPP’), imposing obligations on states to preserve, protect and prosecute the destruction of cultural property, treaties in this area remain silent on the aftermaths of such violence with little attention to reconstruction or reparative measures, thus further endangering sites. Moreover, such treaties emphasise the physical and properterial manifestations of heritage, neglecting its more intangible manifestations that are equally destroyed – such as language and traditions, oral history, songs and dance. As a result there is a vast lacuna in addressing the real impact of war on communities whose cultural heritage, and through it the cultural bonds between individuals and across generations, is destroyed.AHR

One-gas Models with Height-dependent Mean Molecular Weight: Effects on Gravity Wave Propagation

Many models of the thermosphere employ the one-gas approximation where the governing equations apply only to the total gas and the physical properties of the gas that depend on composition (mean molecular weight and specific heats) are height-dependent. It is further assumed that the physical properties of the gas are locally constant; thus motion-induced perturbations are nil. However, motion in a diffusively separated atmosphere perturbs local values of mean molecular weight and specific heats. These motion-induced changes are opposed by mutual diffusion of the constituent gases, which attempts to restore diffusive equilibrium. Assuming that composition is locally constant is equivalent to assuming that diffusion instantaneously damps the changes that winds attempt to produce. This is the limit of fast diffusion. In the limit of slow diffusion, gas properties are constant (conserved) following the motion but are perturbed locally by advection. An analysis of the static stability shows that composition effects significantly change the static stability, with greater changes for the slow-diffusion limit than for the fast-diffusion limit. We have used a one-gas full-wave model to examine the effects of wave-perturbed composition on gravity waves propagating through the lower thermosphere. We have augmented the conventional system (fixed gas properties) with predictive equations for composition-dependent gas properties. These equations include vertical advection and mutual diffusion. The latter is included in parameterized form as second-order scale-dependent diffusion. We have found that the fast diffusion implied by locally fixed properties has a significant effect on the dynamics. Predicted temperatures are larger for locally fixed composition than for conserved composition. The simulations with parameterized mutual diffusion gave results that are much closer to the results for conserved gas properties than for fixed properties. We found that the divergence between the fast and slow limits was greatest for fast waves and for colder thermospheres. This is because the propagation characteristics of fast waves are sensitive to changes in the static stability and because compositional gradients are stronger for colder thermospheres. We conclude that future models that use the one-gas approximation for fast waves in the lower thermosphere should include, at minimum, the simplification of conserved rather than fixed properties, especially for colder thermospheres

Acoustic Waves Generated by Gusty Flow over Hilly Terrain

We examine the generation of acoustic waves by gusty flow over hilly terrain. We use simple theoretical models of the interaction between terrain and eddies and a linear model of acoustic-gravity wave propagation. The calculations presented here suggest that over a dense array of geographically extensive sources orographically generated vertically propagating acoustic waves can be a significant cause of thermospheric heating. This heating may account in good part for the thermospheric hot spot near the Andes reported by Meriwether et al. (1996, 1997)