Early Warning of ionospheric disturbances for GNSS users

Temporal and spatial gradients in the ionosphere can cause major threats on communication and navigation satellite systems, because the propagation of transionospheric radio signals is influenced by the ionospheric electron content. Space weather events are often the source of strong ionospheric disturbances. Forecasting ionospheric perturbations related to space weather events is therefore a crucial task being of special interest for GNSS users. The climatology of ionospheric storms seen in the Total Electron Content (TEC) over Europe as a response of the ionosphere towards Earth oriented space weather events is well known. It depends on season, elapsed time from event arrival, location and local time. However, the deviation of a single storm to the mean behavior can be large. A good correlation between strength of the ionospheric storm, i.e. the maximum deviation of the TEC to 27 day median, to solar wind or geomagnetic activity indices is hard to define. Hence forecasting TEC for disturbed conditions is a challenging task. However, the storm climatology and comprehensive correlation studies allow forecasting of the most probable TEC perturbation amplitude for the European region. GNSS users are in need of information about arriving threads due to space weather events as early as possible. Therefore, an Early Warning message for GNSS users has been developed at the DLR within the FP7-Project AFFECTS. It provides information about Earth endangering space weather events to interested GNSS users up to two days before their arrival. Additional information are now added by a second warning message distributed thirty minutes before arrival at Earth giving more specific information like exact arrival time, forecasts of geomagnetic indices, approximate TEC perturbation and range error for the European region. An overview on the Early Warning for GNSS user service provided by DLR is presented in this paper

Forecast of Total Electron Content over Europe for disturbed ionospheric Conditions

A general picture of the occurrence of ionospheric storms as function of local time, season and location is known from numerous studies over the past 50 years. Nevertheless, it is not yet possible to say how the ionosphere will actually respond to a given space weather event because the measurements of the onset time, location of maximum perturbation, amplitude and type of storm (positive or negative) deviate much from the climatology. However, statistical analyses of numerous storm events observed in the Total Electron Content (TEC) since 1995 enable to estimate and predict a most probable upcoming perturbed TEC over Europe based on forecasts of geomagnetic activity. A first approach will be presented here. The forecast of perturbed TEC is part of the Forecast System Ionosphere build under the umbrella of the FP7 project AFFECTS∗ (Advanced Forecast For Ensuring Communication Through Space). It aims to help users mitigating the impact on communication system

Space Weather services based on operational radio systems

During the past decades a growing number of observations are available, which significantly improve monitoring and modelling of the ionosphere. This is important since radio signals transmitted by modern communication, navigation and Earth observation systems suffer from ionospheric impact due to refraction, diffraction and scattering caused by the ionospheric plasma, depending on the used frequency. Our knowledge on the ionosphere is primarily based on electromagnetic radio waves impacted by the ionospheric plasma. The growing number of GNSS receivers and associated networks supports establishing high precision monitoring of ionospheric weather including perturbation tracking and forecasts usable in space weather services. Other ground based techniques like vertical sounding (VS), Incoherent Scatter Radar (ISR), Very Low Frequency (VLF) or Radio Beacon measurements together with powerful space-based methods, like the Radio Occultation technique provide complementary information. Therefore, the combination of ground- and space-based radio observation data together with appropriate models can provide unique information about the ionosphere and help to mitigate space weather effects on radio systems used in communication, navigation, aviation, satellite operations and earth observation. We like to discuss how well-established and new ionospheric measuring and observation methods might help to improve our understanding of the ionosphere and its impact on operational radio systems

Space weather research and operations at the Institute for Solar-Terrestrial Physics

The Institute of Solar-Terrestrial Physics at the German Aerospace Center, founded in 2019, aims to create the scientific and technological capability to provide timely, accurate and reliable space weather observations and predictions. The institute research covers the state and dynamics of the Ionosphere-Thermosphere-Magnetosphere System and it´s driving by the Sun and by the lower and middle atmosphere. The institute covers both basic research and its development towards user-relevant products to increase the resilience of critical technological infrastructures to space weather impacts. The Ionosphere Monitoring and Prediction Center operated by the institute provides near real-time ionosphere monitoring and predictions of ionospheric conditions to support satellite-based navigation and communication. The presentation will provide a brief overview about the structure of the institute with its observational, research and operational capabilities

Erforschung des Weltraumwetters am DLR Institut für Solar-Terrestrische Physik

Das Weltraumwetter hat einen erheblichen Einfluss auf die Leistung und Zuverlässigkeit von weltraumgestützten und bodengestützten technologischen Systemen und kann hierdurch auch indirekt Menschenleben gefährden. Angesichts der wachsenden Bedeutung von Weltraumwetterinformationen ist 2019 die Gründung eines neuen DLR-Instituts am Standort Neustrelitz in Mecklenburg-Vorpommern (M-V) erfolgt. Das Institut für Solar-terrestrische Physik (SO) befindet sich aktuell in der Aufbauphase und forscht im Bereich Weltraumwetter von den Grundlagen bis zur Anwendung. SO untersucht zeitlich variable Bedingungen auf der Sonne und im Sonnenwind sowie deren Wirkung auf das gekoppelte Ionosphären-Thermosphären-Magnetosphären-System und analysiert Weltraumwettereffekte auf betroffene Technologien in den Bereichen Kommunikation, Navigation, Luftfahrt, Satellitenbetrieb, bemannte Raumfahrt, elektrischer Netzbetrieb und Landvermessung. SO ist daher eine natürliche und notwendige Erweiterung des DLR-Programms „Raumfahrt“ und wird mit seinen Forschungsergebnissen zu wissenschaftlichen und technologischen Anwendungen z.B. im Bereich der Satellitenkommunikation und Navigation, der Erdbeobachtung, des Krisenmanagements, der Kommunikation für die Luftfahrt und der automatisierten Mobilität beitragen. Im Vortrag wird ein Überblick über die existierenden und geplanten Aktivitäten zum Thema Weltraumwetter am DLR Institut für Solar-Terrestrische Physik, sowie deren Einbindung in internationale Weltraumwetteraktivitäten (z.Bsp. ICAO, WMO, ESA, IAG, UN COPUOS), gegeben

Transionospheric Microwave Propagation: Higher-Order Effects up to 100 GHz

Ionospheric refraction is considered as one of the major accuracy limiting factors in microwave space-based geodetic techniques such as the Global Positioning System (GPS), Satellite Laser Ranging (SLR), very-long-baseline interferometry (VLBI), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and satellite altimetry. Similarly, a high-performance ground-to-space and space-to-ground microwave link is considered to be very important for synchronizing clocks in global networks. Moreover, precise time and frequency transfer may lead to new applications in navigation, Earth observation, solar system science, and telecommunications. However, all transionospheric microwave signals are subject to ionospheric refraction and subsequent delays in the travel time. Since the ionosphere is a dispersive medium for radio signals, the first-order propagation effect can be removed by combining signals at two or more frequencies. Anyway, higher-order ionospheric effects remain uncorrected in such combinations. The residuals can significantly affect the accuracy of precise positioning, navigation, as well as the performance of time and frequency transfer. Here, we studied ionospheric propagation effects including higher-order terms for microwave signals up to 100 GHz frequencies. The possible combination between the L, S, C, X, Ku, and Ka band frequencies is studied for the first-order ionosphere-free solutions. We estimated the higher-order propagation effects such as the second- and third-order terms and ray-path bending effects in the dual-frequency group delay and phase advance computation. Moreover, the correction formulas originally developed for global navigation satellite systems (GNSS) L-band frequencies are tested for mitigating residual errors at higher frequencies up to 100 GHz

Impact of space weather on navigation and communication services used in aviation

Space weather can cause significant disruptions to technical infrastructure, resulting in increased risks to safety, economic losses and a reduced quality of life. Space weather can for example have a significant impact on satellite-based communications and navigation services, limiting aviation safety and efficiency. Operators of critical infrastructure are increasingly aware that extreme space weather events can have severe impacts on their systems. Therefore, the international civil aviation organization (ICAO) is operating since 2019 global Space Weather centers with the aim to provide real time information and forecast to the aviation user community. We like to present past and recent examples of Space Weather impact on navigation and communication services in aviation. Furthermore, we will discuss existing products and new developments in respect to their potential in mitigating space weather impact on aviation. Finally, we will also use the available information to evaluate the current situation on the way to the solar maximum of cycle 25

Real-Time Solar Storm Onset Determination at Lagrange Point 1 (L1) Based on an Optimized Effective Pressure Parameter

The solar storm detection parameter, the effective pressure, which is based on a combination of solar wind velocity and the southward component of the interplanetary magnetic field is investigated with data covering two solar cycles to estimate an optimal configuration for its storm detection capabilities. The implementation of the optimized parameter is able to accurately identify the onset time of solar storms with a false alarm rate of less than 2%, which provides a significant better performance than, for example, the proton pressure and has a significant lead time to geomagnetic indices. The effective pressure is further discussed with a selected reference solar storm, showing its potential for storm onset identification

Modellierung CME-getriebener ionosphärischer Störungen für einen Echtzeit-Weltraumwetterservice

Die Vorhersage von ionosphärischen Störungen, welche z.B. durch Sonnenstürme verursacht werden, ist eine wichtige Aufgabe von Weltraumwetterdiensten. Hier wird ein Modell vorgestellt, das eine Langzeitvorhersage (mehr als 12 h) während Sonnenstürmen ermöglicht und im Rahmen eines operationellen Dienstes zur Anwendung kommen soll. Der Modellansatz beruht auf der Auswertung historischer Sonnensturmereignisse (über die letzten zwei Sonnenzyklen), die für die Rekonstruktion zukünftiger Ereignisse verwendet werden. Es werden Ergebnisse der aktuellen Modellimplementierung gezeigt und diskutiert. Weiterhin werden mögliche Erweiterung des Modelles vorgestellt. Zudem wird über die Möglichkeiten diskutiert, die Modellergebnisse für verschiedene Nutzer (insbesondere Nutzer mobiler Anwendungen) zur Verfügung zu stellen