Ionospheric Prediction Service Research Articles

Neural network based model for global Total Electron Content forecasting

We introduce a novel empirical model to forecast, 24 h in advance, the Total Electron Content (TEC) at global scale. The technique leverages on the Global Ionospheric Map (GIM), provided by the International GNSS Service (IGS), and applies a nonlinear autoregressive neural network with external input (NARX) to selected GIM grid points for the 24 h single-point TEC forecasting, taking into account the actual and forecasted geomagnetic conditions. To extend the forecasting at a global scale, the technique makes use of the NeQuick2 Model fed by an effective sunspot number R12 (R12eff), estimated by minimizing the root mean square error (RMSE) between NARX output and NeQuick2 applied at the same GIM grid points. The novel approach is able to reproduce the features of the ionosphere especially during disturbed periods. The performance of the forecasting approach is extensively tested under different geospatial conditions, against both TEC maps products by UPC (Universitat Politècnica de Catalunya) and independent TEC data from Jason-3 spacecraft. The testing results are very satisfactory in terms of RMSE, as it has been found to range between 3 and 5 TECu. RMSE depend on the latitude sectors, time of the day, geomagnetic conditions, and provide a statistical estimation of the accuracy of the 24-h forecasting technique even over the oceans. The validation of the forecasting during five geomagnetic storms reveals that the model performance is not deteriorated during disturbed periods. This 24-h empirical approach is currently implemented on the Ionosphere Prediction Service (IPS), a prototype platform to support different classes of GNSS users.

The ionosphere prediction service prototype for GNSS users

The effect of the Earth’s ionosphere represents the single largest contribution to the Global Navigation Satellite System (GNSS) error budget and abnormal ionospheric conditions can impose serious degradation on GNSS system functionality, including integrity, accuracy and availability. With the growing reliance on GNSS for many modern life applications, actionable ionospheric forecasts can contribute to the understanding and mitigation of the impact of the ionosphere on our technology based society. In this context, the Ionosphere Prediction Service (IPS) project was set up to design and develop a prototype platform to translate the forecast of the ionospheric effects into a service customized for specific GNSS user communities. To achieve this overarching aim, four different product groups dealing with solar activity, ionospheric activity, GNSS receiver performance and service performance have been developed and integrated into a service chain, which is made available through a web based platform. This paper provides an overview of the IPS project describing its overall architecture, products and web based platform.

The development of the Australian Space Forecast Centre (ASFC)

Abstract. The Ionospheric Prediction Service (IPS) was formed in 1947 to provide monthly prediction services for high frequency (HF) radio, in particular to support HF communications with the United Kingdom. It was quickly recognized that to be effective such a service also had to provide advice when ionospheric storms prevented HF communications from taking place. With the advent of the International Geophysical Year (IGY), short-term forecasts were also required for research programmes and the task of supplying the Australian input to these was given to Frank Cook, of the IPS, while Jack Turner, also of the IPS, supervised the generation of ionospheric maps to support high latitude HF communications. These two important IGY activities formed the platform on which all future IPS services would be built. This paper reviews the development of the Australian Space Forecast Centre (ASFC), which arose from these early origins.

A statistical approach to estimate Global Navigation Satellite Systems (GNSS) receiver signal tracking performance in the presence of ionospheric scintillation

Ionospheric scintillation can seriously impair the Global Navigation Satellite Systems (GNSS) receiver signal tracking performance, thus affecting the required levels of availability, accuracy and integrity of positioning that supports modern day GNSS based applications. We present results from the research work carried out under the Horizon 2020 European Commission (EC) funded Ionospheric Prediction Service (IPS) project. The statistical models developed to estimate the standard deviation of the receiver Phase Locked Loop (PLL) tracking jitter on the Global Positioning System (GPS) L1 frequency as a function of scintillation levels are presented. The models were developed following the statistical approach of generalized linear modelling on data recorded by networks in operation at high and low latitudes during the years of 2012–2015. The developed models were validated using data from different stations over varying latitudes, which yielded promising results. In the case of mid-latitudes, as the occurrence of strong scintillation is absent, an attempt to develop a dedicated model proved fruitless and, therefore, the models developed for the high and low latitudes were tested for two mid-latitude stations. The developed statistical models can be used to generate receiver tracking jitter maps over a region, providing users with the expected tracking conditions. The approach followed for the development of these models for the GPS L1 frequency can be used as a blueprint for the development of similar models for other GNSS frequencies, which will be the subject of follow on research.

The Ionosphere Prediction Service

AbstractThe aim of the Ionosphere Prediction Service (IPS) project is to design and develop a prototype platform to translate the prediction and forecast of the ionosphere effects into a service customized for specific GNSS user communities. The project team is composed by Telespazio (coordinator), Nottingham Scientific Ltd, Telespazio Vega Deutschland, the University of Nottingham, the University of Rome “Tor Vergata” and the Italian Istituto Nazionale di Geofisica e Vulcanologia (INGV). The IPS development is conceived of two concurrent activities: prototype service design and development & research activity that will run along the whole project. Service design and development is conceived into four phases: user requirements collection, architecture specification, implementation and validation of the prototype. A sub-activity analyses also the integration feasibility in the Galileo Service center, located in Madrid. The research activity is the scientific backbone of IPS that will provide the models and algorithms for the forecasting products.

Statistical study of the night-time F-layer dynamics at the magnetic equator in West Africa during the solar minimum period 1995–1997

Abstract. In this paper, we report on the night-time equatorial F-layer height behaviour at Korhogo (9.2° N, 5° W; 2.4° S dip lat), Ivory Coast, in the West African sector during the solar minimum period 1995–1997. The data were collected from quarter-hourly ionograms of an Ionospheric Prediction Service (IPS) 42-type vertical sounder. The main focus of this work was to study the seasonal changes in the F-layer height and to clarify the equinox transition process recently evidenced at Korhogo during 1995, the year of declining solar flux activity. The F-layer height was found to vary strongly with time, with up to three main phases. The night-to-night variability of these morphological phases was then analysed. The early post-sunset slow rise, commonly associated with rapid chemical recombination processes in the bottom part of the F layer, remained featureless and was observed regardless of the date. By contrast, the following event, either presented like the post-sunset height peak associated with the evening E × B drift, or was delayed to the midnight sector, thus involving another mechanism. The statistical analysis of the occurrence of these events throughout the solar minimum period 1995–1997 revealed two main F-layer height patterns, each characteristic of a specific season. The one with the post-sunset height peak was associated with the northern winter period, whereas the other, with the midnight height peak, characterized the northern summer period. The transition process from one pattern to the other took place during the equinox periods and was found to last only a few weeks. We discuss these results in the light of earlier works.

Equatorial M(3000) F2 estimation of F2-layer models peak heights during low solar activity

M(3000) F2 estimation of h mF 2 based on four different formulated models viz: (1) Shimazaki (1955) (2) Bradley and Dudeney (1973), (3) Dudeney (1974) and (4) Bilitza et al. (1979) at an equatorial station in West Africa during low solar activity period (1995) are used to validate its conformity with observed and International Reference Ionosphere (IRI) model. Local time analyses of data from fifteen (15) selected days during the January and July solstices and April and October equinoxes are used. The results obtained show that the M(3000) F2 estimation of h mF 2 from the ionosonde-measured values using the Ionospheric Prediction Service (IPS-42) sounder compared to the observed values which were deduced using an algorithm from scaled virtual heights of quiet day ionograms are highly correlated with Bilitza model. International Reference Ionosphere (IRI 2007) model for the equatorial region also agrees with the formulation developed by Bilitza et al. (1979) for the four different seasons of the year. h mF 2 is highest (425 km) in summer (June solstice) season and lowest (386 km) in autumn (September equinox) season with daytimes peaks occurring at 1100 –1200 LT during the solstices and at 1000 LT during the equinoxes respectively. Also, the post-sunset peaks are highest (362 km) at the spring (March equinox) and lowest (308 km) at the summer (June solstice) both occurring between 1800 and 2000 LT.

Comparison of observed hmF2 and IRI 2007 model with M(3000)F2 estimation of hmF2 at low solar activity for an equatorial station

In this paper, the ways of improving the equatorial F2 layer peak heights estimated from M(3000)F2 ionosonde data measured using the Ionospheric Prediction Service (IPS-42) sounder at Ouagadougou, Burkina Faso (geog lat +12.4°N, geog long +1.5°W, magnetic dip +5.9°N) during high solar activity year (1991) was investigated. For this purpose, the observed height of maximum electron density of F2 region (hmF2obs), deduced using an algorithm from scaled virtual heights of quiet day ionograms; and the predicted hmF2 values, which is given by the IRI 2007 model (hmF2IRI2007) have been compared with the ionosonde measured M(3000)F2 estimation of the hmF2 values (hmF2est), respectively. A strong correlation with its coefficients R 2 for all the seasons ranging 0.562 - 0.857 for hmF2obs values, and ranging 0.876 - 0.968 for the hmF2IRI2007 values was observed in the linear regressions of hmF2obs and hmF2IRI2007 with M(3000)F2 inverse. During the nighttime, estimated hmF2 (hmF2est) was found to be positively correlated with the hmF2obs values by the post-sunset peak representation, which is not represented by the hmF2IRI2007 values. Also, the validity of the hmF2est values has been investigated by finding the percentage deviations when compared with the hmF2obs and hmF2IRI2007.

Statistical studies of an effective sunspot number

Two decades ago, the U.S. Air Force Air Weather Service space forecasting group began generating what was termed an effective sunspot number (SSNe) by fitting a model of the critical frequency of the F2 layer (ƒoF2) to observedƒoF2 values. Initially a preprocessing step in a larger analysis package, this parameter has taken on a life of its own and is now used in various applications for both forecasts and specification of the globalƒoF2 field. This paper describes the various ways in which this parameter is calculated, investigates the behavior of this parameter over solar cycle 21 (1976 through 1986), and compares it with other solar‐ionospheric indices, including R12, IF2, IG, and the Ionospheric Prediction Service (IPS) T index.

Ionospheric total electron content and slab thickness determined in Australia

Ionospheric total electron content (TEC) and slab thickness (τ) have been determined for southern Australia from July 1991 to June 1995 using Global Positioning System (GPS) satellite reception and ionograms (at 5‐min intervals) recorded at Salisbury, South Australia, and other Australian ionograms of the Ionospheric Prediction Service Radio and Space Services, Australian Department of Administrative Services. Seasonal, diurnal, and latitudinal variations in TEC and slab thickness are investigated. The removal of possible error sources in GPS measurements such as satellite and receiver biases is considered. Preliminary procedures are outlined in which protonospheric electron content is separated from GPS TEC measurements (up to 20,000 km height) by subtracting Navy Navigation Satellite System (NNSS) measurements (up to 1000 km height). Although slab thickness is substantially constant, there is a trend for increased values at times of reduced solar influence, such as when approaching sunspot minimum. A preliminary report is given of an extension of the current work at Salisbury by using Australian Surveying and Land Information Group GPS receivers at other Australian locations. A comparison is made between the experimental data and values derived from ionospheric models. The two models considered are the international reference ionosphere model (IRI90) and the parameterized ionospheric model ((PIM) version 1.4, February 1996). The GPS TEC measurements near solar minimum were consistently of the order of 5–10 TEC units greater than the model TEC predictions. This difference is attributed to the inclusion of protonospheric TEC in the GPS measurements but not in the model predictions.

Geomagnetic disturbance forecasting at the Ionospheric Prediction Service

"Geomagnetic disturbance forecasting at the Ionospheric Prediction Service." Exploration Geophysics, 17(1), p. 5

Prediction of total electron content using the international Reference Ionosphere

Comparisons are presented between the values of total electron content (TEC) observed at 31°S and those predicted using the Australian Ionospheric Prediction Service's version of the International Reference Ionosphere. Although discrepancies sometimes exceed 30% they are usually less than 20%. The predicted TEC values tend to be too low in daytime summer, too high in daytime winter, and have an incorrect diurnal variation during winter days. Although the predicted TEC was sensitive to the errors in the foF2 values used, the major discrepancies remained.

Dependence of [01] 6300 Å Airglow on Latitude as Observed from Townsville, Australia

AN investigation of the red airglow intensity observed from Townsville shows there is a latitude correlation with ionospheric parameters. Results published by the Commonwealth Ionospheric Prediction Service for vertical incidence soundings at Brisbane, Townsville and Port Moresby (respective geomagnetic latitudes 36.6° S., 28.4° S., 18.5° S.) have been used to investigate the relationship between photometric airglow observations and the parameters ƒoF2 and h′F along an approximate north–south line in the emitting layer above the photometer. Apparently close agreement between diurnal variations of zenith airglow and functions involving ionospheric parameters has already been reported1. This communication deals with the latitude correlation between variations of local zenith airglow and ionospheric data for typical winter and early summer nights.