Claudia Borries

Ionospheric storms—A challenge for empirical forecast of the total electron content

Since the last decades, the functioning of society depends more and more on well-functioning communication and navigation systems. As the availability and reliability of most of these satellite-based systems can be severely impacted by ionospheric storms, the accurate forecast of these events becomes a required task for mitigating social and economic risks. Here we aim to make initial steps toward an empirical model for ionospheric perturbations related to space weather events that are observable in the total electron content (TEC). The perturbation TEC forecast model will be a fast and robust approach, improving TEC forecasts based on climatological models during storm conditions. The derivation of such a model is a challenging task, because although a general dependence of the storm features (enhancement or depletion of electron density) on the storm onset time, local time, season and geomagnetic latitude is well known, there is a large deviation from the mean behavior. For a better understanding of storm conditions, this paper presents analyses of ionospheric storms observed in the TEC, broken down into diverse classes of storms. It provides a detailed characterization of the typical ionospheric storm behavior over Europe from high to midlatitudes, beyond case studies. Generally, the typical clear strong TEC enhancement starting in high latitudes and propagating equatorward is found to be strongest for storms starting in the morning hours independent of the season. In midlatitudes, it is strongest during noon. In addition, a clear difference between summer and winter storms is reported. While only winter storms develop high-latitude TEC enhancements, only summer storms typically exhibit TEC depletions during the storm recovery phase. During winter storms TEC enhancements can also occur the day following the storm onset, in contrast to summer storms. Strong correlation of TEC perturbation amplitudes to the Bz component of the interplanetary magnetic field and to a proxy of the polar cap potential are shown especially for summer midlatitude TEC enhancements during storms with and onset in the morning hours (6 to 12 UT over Europe) and for winter high-latitude TEC enhancements (around 60∘N). The results indicate the potential to derive improved predictions of maximum TEC deviations during space weather events, based on solar wind measurements.

Multiple ionospheric perturbations during the Saint Patrick's Day storm 2015 in the European-African sector

Strong ionospheric perturbations were generated by the intense geomagnetic storm on 17 March 2015. In this article, we are studying perturbations in the European-African sector observed in the total electron content (TEC). Focal points are wavelike phenomena considered as large-scale traveling ionospheric disturbances (LSTIDs). In the European-African sector, the storm produced three different types of LSTIDs: (1) a concurrent TEC perturbation at all latitudes simultaneously; (2) one LSTID propagating toward the equator, having very large wave parameters (wavelength: ≈3600 km, period: ≈120 min, and speed: ≈500 m/s); and (3) several LSTIDs propagating toward the equator with typical wave parameters (wavelength: ≈2100 km, period: ≈60 min, and speed ≈600 m/s). The third type of LSTIDs is considered to be exited as most LSTIDs either due to variations in the Joule heating or variations in the Lorentz force, whereas the first two perturbation types are rather unusual in their appearance. They occurred during the partial recovery phase when the geomagnetic perturbations were minor and the interplanetary magnetic field turned northward. A westward prompt penetration electric field is considered to excite the first perturbation signature, which indicates a sudden TEC depletion. For the second LSTID type, variations in the Lorentz force because of perturbed electric fields and a minor particle precipitation effect are extracted as possible excitation mechanisms.

On the dynamics of large‐scale traveling ionospheric disturbances over Europe on 20 November 2003

Ionospheric disturbances, often associated with geomagnetic storms, may cause threats to radio systems used for communication and navigation. One example is the super storm on 20th November 2003, when plenty of strong and unusual perturbations were reported. This paper reveals additional information on the dynamics in the high latitude ionosphere over Europe during this storm. Here, analyses of wavelike Travelling Ionospheric Distrubances (TIDs) over Europe are presented, based on estimates of the Total Electron Content (TEC) derived from ground-based Global Navigation Satellite System (GNSS) measurements. These TIDs are ionospheric signatures of thermospheric surges initiated by space weather events. The source region of these TIDs is characterized by enhanced spatial gradients, TEC depression, strong uplift of the F2-layer, the vicinity of the eastward auroral electrojet and strong aurora E-layers. Joule heating is identified as the most probable driver for the TIDs observed over Europe during 20th November 2003. The sudden heating of the thermosphere leads to strong changes in the pressure and thermospheric wind circulation system, which in turn generates thermospheric wind surges observed as TID signatures in the TEC. Either the dissipation of the eastward auroral electrojet or particle precipitation are considered as the source mechanism for the Joule heating.In the course of the storm, the TEC observations show a southward shift of the source region of the TIDs. These meridional dislocation effects are obviously related to a strong compression of the plasmasphere. The presented results demonstrate the complex interaction processes in the thermosphere-ionosphere-magnetosphere system during this extreme storm.

Services for GNSS users within the ESA Space Situational Awareness Space Weather Service Network

Ionospheric Space Weather can adversely degrade the performance of radio systems in communication, space based navigation and remote sensing. Navigation signals transmitted by Global Navigation Satellite Systems (GNSS) are delayed, refracted and diffracted by the highly variable ionosphere affecting the accuracy, availability, continuity and integrity of GNSS signals which can be crucial in safety of life and precise positioning applications. Therefore detection, monitoring and prediction of ionospheric effects are important for mitigating such impact. In the frame of its Space Situational Awareness (SSA) programme, the European Space Agency (ESA) is establishing a Space Weather Service Network to support end-users, in a wide range of affected sectors, in mitigating the effects of space weather on their systems, reducing costs and improving reliability. In this paper we present an overview of the current status of the network, the targeted end user groups and Expert Service Centers (ESCs). Focusing on the ESC for Ionospheric Weather (I-ESC), we report on the currently available products and tools as well as on the recent and ongoing activities in expanding the network for this domain.

PRE-EARTHQUAKES, an FP7 project for integrating observations and knowledges on earthquake precursors: Preliminary results and strategy

PRE-EARTHQUAKES (Processing Russian and European EARTH observations for earthQUAKE precursors Studies) EU-FP7 project is devoted to demonstrate - integrating different observational data, comparing and improving different data analysis methods - how it is possible to progressively increase reliability of short term seismic risk assessment. Three main testing area were selected (Italy, Turkey and Sakhalin) in order to concentrate observations and integration efforts starting with a learning phase on selected events in the past devoted to identify the most suitable parameters, observations technologies, data analysis algorithms. For these areas, different ground (80 radon and 29 spring water stations in Turkey region, 2 magneto-telluric in Italy) and satellite (18 different systems) based observations, 11 data analysis methods, for 7 measured parameters, have been compared and integrated. A specific integration platform (PEG, Pre-Earthquakes Geoportal) based on OGC (Open Geospatial Consortium) standards, was developed to operate a products integration, cross-validation and scientific interpretation.

Services for Space Mission support within the ESA Space Situational Awareness Space Weather Service Network.

Spacecraft operations are by nature complex and every satellites operational environment poses a range of potential risks, often a unique combination for a given orbit. The implications of interruptions of operations, data transfer and service provision, are serious, both in terms of cost and capability, thus it is imperative to mitigate against all operational risks to the fullest extent possible. In the frame of its Space Situational Awareness (SSA) programme, the European Space Agency (ESA) is establishing a Space Weather Service Network to support end-users, in a wide range of affected sectors, in mitigating the effects of space weather on their systems, reducing costs and improving reliability. This service network is currently in a test and validation phase and encourages user engagement and feedback. The network is organised around five Expert Service Centres (ESCs) focusing on Solar Weather, Heliospheric Weather, Space Radiation Environment, Ionospheric Weather and Geomagnetic Conditions. Each ESC is connecting different expert groups, federating their space weather products, and ensuring the quality and consistency of the provided information. The service network also includes a central Data Centre and the SSA Space Weather Coordination Centre (SSCC). In this presentation we give an overview of the current status of the network (http://swe.ssa.esa.int/), the targeted end-user groups and Expert Service Centres with a focus on the space community.

Services for Spacecraft Operations support within the ESA Space Situational Awareness Space Weather Service Network

Spacecraft operations are by nature complex and every satellites operational environment poses a range of potential risks, often a unique combination for a given orbit. The implications of interruptions of operations, data transfer and service provision, are serious, both in terms of cost and capability, thus it is imperative to mitigate against all operational risks to the fullest extent possible. In the frame of its Space Situational Awareness (SSA) programme, the European Space Agency (ESA) is establishing a Space Weather Service Network to support end-users, in a wide range of affected sectors, in mitigating the effects of space weather on their systems, reducing costs and improving reliability. This service network is currently in a test and validation phase and encourages user engagement and feedback. The network is organised around five Expert Service Centres (ESCs) focusing on Solar Weather, Heliospheric Weather, Space Radiation Environment, Ionospheric Weather and Geomagnetic Conditions. Each ESC is connecting different expert groups, federating their space weather products, and ensuring the quality and consistency of the provided information. The service network also includes a central Data Centre and the SSA Space Weather Coordination Centre (SSCC). In this presentation we give an overview of the current status of the network (http://swe.ssa.esa.int/), the targeted end-user groups and Expert Service Centres with a focus on the space community. Keywords—space weather, space situational awareness, service network