Temporal variations of thermospheric hydrogen derived from in situ measurements

Diurnal variations of atomic hydrogen in thermosphere derived from Explorer 32 data and correlated with solar cycle, solar rotation, and earth rotatio

Thermospheric hydrogen - Absolute densities and temporal variations deduced from in situ measurements

Thermospheric model based on Explorer 32 hydrogen ion density measurements including periodic variations and temperature factors due to local time, solar activity, and magnetic effect

Altitude variation of ion composition in the midlatitude trough region - Evidence for upward plasma flow

Altitude effect on ion concentration in midlatitude trough and plasmaspher

Observation of hydrogen and helium ions during a period of rising solar activity

Latitudinal variations in H and He ion distribution in upper ionosphere observed by OGO 2 and 4 satellites during rising solar activit

A theoretical model of the ionosphere dynamics with interhemispheric coupling

Dynamic model for ionospheric plasma with interhemispheric couplin

08181 Abstracts Collection -- The Evolution of Conceptual Modeling

From 24.04. to 30.04.2008, the Dagstuhl Seminar 08181 ``The Evolution of Conceptual Modeling\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Towards quality-aware predesign model

An approach to capturing the semantics of qualityrequirements into an intermediate predesign model is outlined. This approach combines Klagenfurt Conceptual Predesign and Aspectual Predesign techniques. Proposed extensions in corporate the hierarchy of quality characteristics into the predesign model and represent crosscutting relationships between the quality concerns and the main functionality of the system. Some directions of integration of the proposed model into quality-driven software process are discussed.У статті розглядаються основи підходу до збирання семантики вимог якості у проміжну предпроектну модель. Цей підхід є поєднанням технологій Клагенфуртського концептуального предпроектування та аспектного предпроектування. Запропоновані додатки дозволяють включити до моделі іерархію характеристик якості та подати наскрізні відношини між інтересами якості та основною функціональністю системи. Обговорені деякі напрямки інтеграції запропонованої моделі у процесс розробки програмного забезпечення, що керується якістю

Untangling the Conceptual Isssues Raised in Reydon and Scholz’s Critique of Organizational Ecology and Darwinian Populations

Reydon and Scholz raise doubts about the Darwinian status of organizational ecology by arguing that Darwinian principles are not applicable to organizational populations. Although their critique of organizational ecology’s typological essentialism is correct, they go on to reject the Darwinian status of organizational populations. This paper claims that the distinction between replicators and interactors, raised in modern philosophy of biology but not discussed by Reydon and Scholz, points the way forward for organizational ecologists. It is possible to conceptualise evolving Darwinian populations providing the inheritance mechanism is appropriately specified. By this approach, adaptation and selection are no longer dichotomised, and the evolutionary significance of knowledge transmission is highlightedPeer reviewe

A modified Monte Carlo model for the ionospheric heating rates

A Monte Carlo method is adopted as a basis for the derivation of the photoelectron heat input into the ionospheric plasma. This approach is modified in an attempt to minimize the computation time. The heat input distributions are computed for arbitrarily small source elements that are spaced at distances apart corresponding to the photoelectron dissipation range. By means of a nonlinear interpolation procedure their individual heating rate distributions are utilized to produce synthetic ones that fill the gaps between the Monte Carlo generated distributions. By varying these gaps and the corresponding number of Monte Carlo runs the accuracy of the results is tested to verify the validity of this procedure. It is concluded that this model can reduce the computation time by more than a factor of three, thus improving the feasibility of including Monte Carlo calculations in self-consistent ionosphere models

The QBO as potential amplifier and conduit to lower altitudes of solar cycle influence

International audienceIn several papers, the solar cycle (SC) effect in the lower atmosphere has been linked observationally to the Quasi-biennial Oscillation (QBO) of the zonal circulation. Salby and Callaghan (2000) in particular analyzed the QBO wind measurements, covering more than 40 years, and discovered that they contain a large SC signature at 20 km. We present here the results from a study with our 3-D Numerical Spectral Model (NSM), which relies primarily on parameterized gravity waves (GW) to describe the QBO. In our model, the period of the SC is taken to be 10 years, and the relative amplitude of radiative forcing varies exponentially with height, i.e., 0.2% at the surface, 2% at 50 km, and 20% at 100 km and above. Applying spectral analysis to identify the SC signature, the model generates a relatively large modulation of the QBO, which reproduces the observations qualitatively. The numerical results demonstrate that the QBO modulation, closely tracking the phase of the SC, is robust and persists at least for 70 years. The question is what causes the SC effect, and our analysis shows that four interlocking processes are involved: (1) In the mesosphere at around 60 km, the solar UV variations generate in the zonal winds a SC modulation of the 12-month annual oscillation, which is hemispherically symmetric and confined to equatorial latitudes like the QBO. (2) Although the amplitude of this equatorial annual oscillation (EAO) is relatively small, its SC modulation is large and extends into the lower stratosphere under the influence of, and amplified by, wave forcing. (3) The amplitude modulations of both EAO and QBO are essentially in phase with the imposed SC heating for the entire time span of the model simulation. This indicates that, due to positive feedback in the wave mechanism, the EAO apparently provides the pathway and pacemaker for the SC modulation of the QBO. (4) Our analysis demonstrates that the SC modulations of the QBO and EAO are amplified by tapping the momentum from the upward propagating gravity waves. Influenced and amplified by wave processes, the QBO thus acts as conduit to transfer to lower altitudes the larger SC variations in the UV absorbed in the mesosphere. Our model produces in the temperature variations of the QBO and EAO measurable SC modulations at polar latitudes near the tropopause. The effects are apparently generated by the meridional circulation, and planetary waves presumably, which redistribute the energy from the equatorial region where the waves are very effective in amplifying the SC influence