Numerical simulations of the seasonal/latitudinal variations of atomic oxygen and nitric oxide in the lower thermosphere and mesosphere

A 2-Dimensional zonally-averaged thermospheric model and the global University College London (UCL) thermospheric model have been used to investigate the seasonal, solar activity and geomagnetic variation of atomic oxygen and nitric oxide. The 2-dimensional model includes detailed oxygen and nitrogen chemistry, with appropriate completion of the energy equation, by adding the thermal infrared cooling by O and NO. This solution includes solar and auroral production of odd nitrogen compounds and metastable species. This model has been used for three investigations; firstly, to study the interactions between atmospheric dynamics and minor species transport and density; secondly, to examine the seasonal variations of atomic oxygen and nitric oxide within the upper mesosphere and thermosphere and their response to solar and geomagnetic activity variations; thirdly, to study the factor of 7 to 8 peak nitric oxide density increase as solar F sub 10.7 cm flux increases from 70 to 240 reported from the Solar Mesospheric Explorer. Auroral production of NO is shown to be the dominant source at high latitudes, generating peak NO densities a factor of 10 greater than typical number densities at low latitudes. At low latitudes, the predicted variation of the peak NO density, near 110 km, with the solar F sub 10.7 cm flux is rather smaller than is observed. This is most likely due to an overestimate of the soft X-ray flux at low solar activity, for times of extremely low support number, as occurred in June 1986. As observed on pressure levels, the variation of O density is small. The global circulation during solstice and periods of elevated geomagnetic activity causes depletion of O in regions of upwelling, and enhancements in regions of downwelling

Multi-site Action Research

Classical action research within single organizations has become a well established and differentiated approach since its inception more than six decades ago. Although new larger scale varieties of action research are beginning to develop, there is still a clear need to expand the scope of action research practice (Greenwood, 2002). Building on previous work, this paper develops multi-site action research (MAR) as a conceptually distinct variant of action research implementation with promising potential to fill the gap between the classical and coalition type varieties of action research. MAR is defined as involving the concurrent implementation of multiple distinct single-site action research processes, with a similar focus, and some level of coordination across sites. From a review of three relevant multi-site initiatives, a conceptual framework for the potential benefits of MAR is derived, and a model of the MAR implementation process is presented and discussed

Understanding the Latitude Structure of Nitric Oxide in the Mesosphere and Lower Thermosphere

The goal of the proposed work was to understand the latitude structure of nitric oxide in the mesosphere and lower thermosphere. The problem was portrayed by a clear difference between predictions of the nitric oxide distribution from chemical/dynamical models and data from observations made by the Solar Mesosphere Explorer (SMEE) in the early to mid eighties. The data exhibits a flat latitude structure of NO, the models tend to produce at equatorial maximum. The first task was to use the UARS-HALOE data to confirm the SME observations. The purpose of this first phase was to verify the UARS-NO structure is consistent with the SME data. The next task was to determine the cause of the discrepancy between modeled and observed nitric oxide latitude structure. The result from the final phase indicated that the latitude structure in the Photo-Electron (PE) production rate was the most important

Self-consistent modelling of the polar thermosphere and ionosphere to magnetospheric convection and precipitation (invited review)

It has recently been demonstrated that the dramatic effects of plasma precipitation and convection on the composition and dynamics of the polar thermosphere and ionosphere include a number of strong interactive, or feedback, processes. To aid the evaluation of these feedback processes, a joint three dimensional time dependent global model of the Earth's thermosphere and ionosphere was developed in a collaboration between University College London and Sheffield University. This model includes self consistent coupling between the thermosphere and the ionosphere in the polar regions. Some of the major features in the polar ionosphere, which the initial simulations indicate are due to the strong coupling of ions and neutrals in the presence of strong electric fields and energetic electron precipitation are reviewed. The model is also able to simulate seasonal and Universal time variations in the polar thermosphere and ionospheric regions which are due to the variations of solar photoionization in specific geomagnetic regions such as the cusp and polar cap

The modelled occurrence of non-thermal plasma in the ionospheric F-region and the possible consequences for ion outflows into the magnetosphere

A global, time-dependent, three-dimensional, coupled ionosphere-thermosphere model is used to predict the spatial distribution of non-thermal plasma in the F-layer. It is shown that, even for steady-state conditions with Kp as low as 3, the difference between the ion and neutral velocities often exceeds the neutral thermal speed by a factor, D', which can be as large as 4. Theoretically, highly non-Maxwellian, and probably toroidal, ion velocity distributions are expected when D' exceeds about 1.5. The lack of response of the neutral winds to sunward ion drifts in the dawn sector of the auroral oval cause this to be the region most likely to contain toroidal distributions. The maximum in D' is found in the throat region of the convection pattern, where the strong neutral winds of the afternoon sector meet the eastward ion flows of the morning sector. These predictions are of interest, not only to radar scientists searching for non-thermal ionospheric plasma, but also as one possible explanation of the initial heating and upward flows of ions in the cleft ion fountain and nightside auroral oval, both of which are a major source of plasma for the magnetosphere

Changing associations between socioeconomic status and self-reported discrimination from the 1990s to the 2010s in the United States

We examined whether prevalence of social class discrimination-and its association with psychological distress-has changed between 1990s and 2010s in the United States. Data were from the original Midlife in the United States (MIDUS) study with data collections in 1995-1996 (n = 2931) and 2004-2005 (n = 1708), and the new MIDUS Refresher sample from 2011 to 2014 (n = 2543). Socioeconomic status (SES) became more strongly associated with self-rated discrimination over time, with individuals with the lowest SES experiencing more discrimination (B = 0.75, p < .001) and those with the highest SES less discrimination (B = 0.36, p < .001) over time: at baseline, the difference in self-rated discrimination between the highest and lowest SES groups was 15.3% versus 10.8% (4.7% point difference). This difference increased to 20.0% versus 7.4% in the last study wave (12.6% point difference). Association between self-reported discrimination and psychological distress strengthened over time, but the associations between socioeconomic indicators and distress did not change. The results suggest that people with low SES had higher risk of encountering unfair and disrespectful treatment in the 2010s compared to the 1990s.Peer reviewe

The influence of anisotropic F region ion velocity distributions on ionospheric ion outflows into the magnetosphere

The contribution to the field-aligned ionospheric ion momentum equation, due to coupling between pressure anisotropy and the inhomogeneous geomagnetic field, is investigated. We term this contribution the “hydrodynamic mirror force” and investigate its dependence on the ion drift and the resulting deformations of the ion velocity distribution function from an isotropic form. It is shown that this extra upforce increases rapidly with ion drift relative to the neutral gas but is not highly dependent on the ion-neutral collision model employed. An example of a burst of flow observed by EISCAT, thought to be the ionospheric signature of a flux transfer event at the magnetopause, is studied in detail and it is shown that the nonthermal plasma which results is subject to a hydrodynamic mirror force which is roughly 10% of the gravitational downforce. In addition, predictions by the coupled University College London-Sheffield University model of the ionosphere and thermosphere show that the hydrodynamic mirror force in the auroral oval is up to 3% of the gravitational force for Kp of about 3, rising to 10% following a sudden increase in cross-cap potential. The spatial distribution of the upforce shows peaks in the cusp region and in the post-midnight auroral oval, similar to that of observed low-energy heavy ion flows from the ionosphere into the magnetosphere. We suggest the hydrodynamic mirror force may modulate these outflows by controlling the supply of heavy ions to regions of ion acceleration and that future simulations of the effects of Joule heating on ion outflows should make allowance for it

Review of current and planned activities of the International Space Weather Activity Team on Ionospheric Indices and Scales (ISWAT G2B-04)

Ionospheric indices have a high potential to support and contribute fulfilling user requirements in ground and space-based radio system applications such as HF communication, GNSS based safe navigation and precise positioning. Following the discussions at previous COSPAR assemblies, the International Space Weather Activity Team (ISWAT) G2B-04, established in 2021, encourage studies and test runs to specify the effectiveness of different types of ionospheric indices and scales. To fill the current gap in the NOAA SW scales in particular for trans-ionospheric radio system applications is one of the main tasks. Recently, the team has initiated a Coordinated Ionospheric Study on Scales and Indices (CISSI) to enable a comparison of the outcome of different index approaches based on almost identical data sets available at 4 different continental regions in two selected periods in 2015. Preliminary results were reported at recent ISWAT team meetings and are fortunately presented in this PSW.3 session too. Indeed, the team members are encouraged to closely collaborate, interact with customers groups, and present their results at international meetings and in journal publications. In this talk we review the current state and achievements of the ISWAT G2B-04 team activities and in particular, consider future tasks that should be addressed in this team including the contribution to the next COSPAR space weather road map. Key aspects of our future work are: • Enhanced comparative analysis of different indices based on studies utilizing an identical data base. • Identification of specific advantages and drawbacks of different indices focusing both on basic research and practical applications. These efforts are supported by the compilation of fact sheets for all available indices, suggested and discussed by the team members. • Definition of an Ionospheric Scale applicable for a wide spectrum of applications in space-based radio systems in close collaboration with customers e.g. in precise positioning and safety of life navigation • International collaboration in space weather monitoring, warning and forecasting as required, for example by the International Civil Aviation Organization (ICAO), and the need for a ‘common language’ in communication and data exchange. Therefore, definition and standardization of a practically-oriented scale designed for user-friendly space weather services are important tasks

Impact of the altitudinal Joule heating distribution on the thermosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95601/1/jgra20978.pd