Validation Study of the Ionospheric Forecast Model Using the TOPEX TEC Measurements

As a part of the validation program in the Utah State University Global Assimilation of Ionospheric Measurement (GAIM) project, a newly improved Ionosphere Forecast Model (IFM) was systematically validated by using a large database of TOPEX total electron content (TEC) measurements. The TOPEX data used for the validation are for the period from August 1992 to March 2003, and the total number of 18-s averaged data is close to 11 million. This model validation work covers a wide range of seasonal (winter, summer, and equinox) and solar (low-F 10.7, median F 10.7, and high-F 10.7) conditions as well as all UT variations with the focus on nonstorm time TEC. The validation results indicate that the features of the spatial distribution of the IFM TEC are systematically consistent with those of the TOPEX TEC. The differences between the IFM TEC and the TOPEX TEC are within 20% for almost all locations and conditions. For many conditions, the differences are even below 10%

Ensemble Modeling with Data Assimilation Models: A New Strategy for Space Weather Specifications, Forecasts, and Science

The Earth’s Ionosphere-Thermosphere-Electrodynamics (I-T-E) system varies markedly on a range of spatial and temporal scales and these variations have adverse effects on human operations and systems, including high-frequency communications, over-the-horizon radars, and survey and navigation systems that use Global Positioning System (GPS) satellites. Consequently, there is a need to elucidate the underlying physical pro- cesses that lead to space weather disturbances and to both mitigate and forecast near-Earth space weather

A consensus research agenda for optimising nasal drug delivery

Nasal drug delivery has specific challenges which are distinct from oral inhalation, alongside which it is often considered. The next generation of nasal products will be required to deliver new classes of molecule, e.g. vaccines, biologics and drugs with action in the brain or sinuses, to local and systemic therapeutic targets. Innovations and new tools/knowledge are required to design products to deliver these therapeutic agents to the right target at the right time in the right patients. We report the outcomes of an expert meeting convened to consider gaps in knowledge and unmet research needs in terms of (i) formulation and devices, (ii) meaningful product characterization and modeling, (iii) opportunities to modify absorption and clearance. Important research questions were identified in the areas of device and formulation innovation, critical quality attributes for different nasal products, development of nasal casts for drug deposition studies, improved experimental models, the use of simulations and nasal delivery in special populations. We offer these questions as a stimulus to research and suggest that they might be addressed most effectively by collaborative research endeavors

CEDARâ GEM Challenge for Systematic Assessment of Ionosphere/Thermosphere Models in Predicting TEC During the 2006 December Storm Event

In order to assess current modeling capability of reproducing storm impacts on total electron content (TEC), we considered quantities such as TEC, TEC changes compared to quiet time values, and the maximum value of the TEC and TEC changes during a storm. We compared the quantities obtained from ionospheric models against groundâ based GPS TEC measurements during the 2006 AGU storm event (14â 15 December 2006) in the selected eight longitude sectors. We used 15 simulations obtained from eight ionospheric models, including empirical, physicsâ based, coupled ionosphereâ thermosphere, and data assimilation models. To quantitatively evaluate performance of the models in TEC prediction during the storm, we calculated skill scores such as RMS error, Normalized RMS error (NRMSE), ratio of the modeled to observed maximum increase (Yield), and the difference between the modeled peak time and observed peak time. Furthermore, to investigate latitudinal dependence of the performance of the models, the skill scores were calculated for five latitude regions. Our study shows that RMSE of TEC and TEC changes of the model simulations range from about 3 TECU (total electron content unit, 1 TECU = 1016 el mâ 2) (in high latitudes) to about 13 TECU (in low latitudes), which is larger than latitudinal average GPS TEC error of about 2 TECU. Most model simulations predict TEC better than TEC changes in terms of NRMSE and the difference in peak time, while the opposite holds true in terms of Yield. Model performance strongly depends on the quantities considered, the type of metrics used, and the latitude considered.Key PointsTEC and TEC changes during a storm predicted by ionosphere models were compared with groundâ based GPS TEC measurementsSkill scores (e.g., RMSE, NRMSE, and Yields) were calculated for five latitude regions in the selected eight longitude sectorsModel performance strongly depends on the quantities considered, the type of metrics used, and the latitude consideredPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139943/1/swe20516.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139943/2/swe20516_am.pd

CEDAR Electrodynamics Thermosphere Ionosphere (ETI) Challenge for systematic assessment of ionosphere/thermosphere models: Electron density, neutral density, NmF2, and hmF2 using space based observations

In an effort to quantitatively assess the current capabilities of Ionosphere/Thermosphere (IT) models, an IT model validation study using metrics was performed. This study is a main part of the CEDAR Electrodynamics Thermosphere Ionosphere (ETI) Challenge, which was initiated at the CEDAR workshop in 2009 to better comprehend strengths and weaknesses of models in predicting the IT system, and to trace improvements in ionospheric/thermospheric specification and forecast. For the challenge, two strong geomagnetic storms, four moderate storms, and three quiet time intervals were selected. For the selected events, we obtained four scores (i.e., RMS error, prediction efficiency, ratio of the maximum change in amplitudes, and ratio of the maximum amplitudes) to compare the performance of models in reproducing the selected physical parameters such as vertical drifts, electron and neutral densities, NmF2, and hmF2. In this paper, we present the results from comparing modeled values against space-based measurements including NmF2 and hmF2 from the CHAMP and COSMIC satellites, and electron and neutral densities at the CHAMP satellite locations. It is found that the accuracy of models varies with the metrics used, latitude and geomagnetic activity level

Quantitative estimates of relationships between geomagnetic activity and equatorial spread-F as determined by TID occurrence levels

Using a world-wide set of stations for 15 years, quantitative estimates of changes to equatorial spread-F (ESF) occurrence rates obtained from ionogram scalings, have been determined for a range of geomagnetic activity (GA) levels, as well as for four different levels of solar activity. Average occurrence rates were used as a reference. The percentage changes vary significantly depending on these subdivisions. For example for very high GA the inverse association is recorded by a change of -33% for R-z greater than or equal to 150, and -10% for R-z < 50. Using data for 9 years for the equatorial station, Huancayo, these measurements of ESF which indicate the presence of TIDs, have also been investigated by somewhat similar analyses. Additional parameters were used which involved the local times of GA, with the ESF being examined separately for occurrence pre-midnight (PM) and after-midnight (AM). Again the negative changes were most pronounced for high GA in R-z-max years (-21%). This result is for PM ESF for GA at a local time of 1700. There were increased ESF levels (+31%) for AM ESF in R-z-min years for high GA around 2300 LT. This additional knowledge of the influence of GA on ESF occurrence involving not only percentage changes, but these values for a range of parameter levels, may be useful if ever short-term forecasts are needed. There is some discussion on comparisons which can be made between ESF results obtained by coherent scatter from incoherent-scatter equipment and those obtained by ionosondes