Session 15 - GNSS: How can the space weather community meet user requirements for navigation/communication at high latitudes?

Behlke Rico (SST); Geoff Crowley (ASTRA)
Friday 22/11, 09:00-10:30
Elisabeth

The decrease of sea ice in the Arctic has led to a substantial increase in maritime operations in this area. In the end of December 2018, the fishing vessel Northguider ran aground at 79° North in the vicinity of Svalbard in the middle of the polar night. Local rescue services managed to extract all personnel from the vessel, but where hampered by severe weather and degraded communication. Navigation and communication solutions at high latitudes suffer from a variety of factors such as sparse groundbased infrastructure, icing on hardware, limited availability of Satellite and Ground Based Augmentation Systems (SBAS and GBAS), limited visibility of geostationary satellites, degraded visibility during a substantial time of the year (polar night) and a variety of space weather related effects.

This sessions aims to present the challenges the user community experiences at high latitudes as well as existing and future solutions which the space weather community can provide.

Talks
Friday November 22, 09:00 - 10:30, Elisabeth

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Talks : Time schedule

Friday November 22, 09:00 - 10:30, Elisabeth

09:00	Highly Elliptical Orbits for services in Polar Regions: Increasing the mission lifetime by orbit optimization	Trichtchenko, L et al.	Oral
	L. Trichtchenko[1], A. Trishchenko[1] and L. Garand[2]
	[1] Natural Resources Canada,[2] Environment and Climate Change Canada
	The satellite missions on Highly Elliptical Orbit (HEO) present an attractive opportunity to improve communications, meteo and space weather services for Earth’s polar regions based on their unique capability of continuous coverage these, otherwise not well covered, regions. Some HEO orbits, such as 12-h Molniya and 24-h Tundra orbit, have been used for a very long time for communications and special applications (example surveillance and early-warning systems). Recently, a number of studies has been conducted to determine the most suitable HEO orbit (covering the HEO orbits with periods from 6 h to 24 h), which would minimize the hazardous space environment effects affecting the mission performance. This study reports results of the analysis on further minimization of the total ionizing doze (TID) for the 14-h, 15-h and 16-h HEO orbits that have some unique observational features related to viewing the polar zone from multiple apogee locations. The assessment of space radiation environment has been conducted with the use of ESA’s SPENVIS tool. The minimization has been achieved by more optimal orbit placement with respect to trapped electrons. Reduction in TID converts into reduction of the thickness of aluminum shielding by factor 1.24-1.28 or an equivalent increase in the mission lifetime by up to 8 years. Thus, by careful choice of satellite orbits, the extended service can be provided to high latitude areas with use of HEO missions.
09:15	An index for estimating the degree of ionospheric disturbance	Wilken, V et al.	Oral
	Volker Wilken[1], Martin Kriegel[2], Norbert Jakowski[3], Jens Berdermann[4]
	German Aerospace Center (DLR), Institute of Communications and Navigation, Germany, Kalkhorstweg 53, D-17235 Neustrelitz
	Space weather has the potential to strongly influence trans-ionospheric radio signals depending on the frequency used. To adequately assess the intensity of a space weather event, a number of measurements are necessary, e.g. from the sun, the solar wind, the magnetosphere and the ionosphere. In combination with the corresponding classification systems, these measurements and parameters provide orientation in a physically complex environment. In order to provide end-users with a simplified but appropriate situational awareness, easily interpretable indices are derived from key measurements. Here we focus on the recognition and description of ionospheric spatial TEC gradients using the Disturbance Ionosphere Index Spatial Gradient (DIXSG). Since DIXSG was recommended to serve as a global ionospheric spatial weather index at a workshop on Ionospheric Indices and scales during the 42nd COSPAR Scientific Assembly, Pasadena, 2018, we would like to present its capabilities in detail on test-cases.
09:30	Method for estimating foF2 from GPS/TEC	Bouya, Z et al.	Oral
	Z. Bouya, V. Kumar, M. Terkildsen, P. Maher
	Space Weather Services, Australian Bureau of Meteorology, Sydney, Australia
	The Australian Bureau of Meteorology through its Space Weather Service (SWS) provides ionospheric products and services to a diverse group of customers. This paper proposes a new approach to investigating the possibility of estimating foF2 from Total Electron Content(TEC). In this work, GNSS measurements which provide another measure of ionosphere characteristics will be incorporated to augment foF2 modelling and forecasting applicable to geographic locations where measured data are not readily available. By performing this analysis, it will be possible to addresses the issues of outliers, missing information and fill in gaps in foF2 data.
09:45	ESA Space Weather portal -- GNSS Performance Indicator Tool	Jacobsen, K et al.	Oral
	Knut Stanley Jacobsen
	Norwegian Mapping Authority
	The GNSS performance indicator (GPI) tool aims to provide a dedicated user-tailored interface utilising multiple products already integrated into the I-ESC in order to provide the SWE end user with an indication of current GNSS uncertainties resulting from ionospheric conditions. This year, an initial web interface has been established and deployed to the portal. This tool is designed in such a way that it can be easily enhanced in subsequent activities with data and models for different GNSS use cases. The initial web interface includes a fully functional service for the use case "Professional Network RTK User". The tool is also available as a web service, for machine-to-machine integration into other tools or services. Potential future enhancements include additional use cases as well as more advanced display of data (e.g. dynamic time series and maps). We present the current state of the GPI tool, its web and machine-to-machine interfaces, and the requirements for defining a new use case to be integrated into the tool.
10:00	Appropriate ionosphere perturbation indices for use cases in high latitudes	Borries, C et al.	Oral
	Claudia Borries[1], Volker Wilken[1], Knut Stanley Jacobsen[2], Alberto Garcia-Rigo[3], Beata Dziak-Jankowska[4], Guram Kervalishvili[5], Norbert Jakowski[1], Ioanna Tsagouri[6], Manuel Hernández-Pajares[3]
	[1] German Aerospace Center, Neustrelitz, Germany, [2] Norwegian Mapping Authority, Honefoss, Norway, [3] University of Catalonia, Barcelona, Spain, [4] Space Research Center, Polish Academy of Science, Warsaw, Poland, [5] German Geoscience Centre, Potsdam, Germany, [6] National Observatory of Athens, Athens, Greece
	Because the propagation of radio signals is sensitive to the electron density in the ionosphere, ionospheric perturbations are of great interest for applications using radio systems (e.g. GNSS and HF communication). Especially high latitudes are impacted by manifold ionospheric perturbations, which can have different characteristics. Their spatial range can vary between global and very local effects (e.g. a few hundreds of km range) and their temporal range varies between seconds and days. All these perturbations have different physical background and different impact on applications. Therefore, many ionosphere perturbation indices characterizing ionospheric perturbations have been introduced in the past (e.g. ROTI, S4, σφ, AATR, Reff, W-index, SISTED, SOLERA, DIXSG, IBI, Dfu/Dfl, etc.). This presentation provides a summary overview on a subset of 19 ionospheric indices that were developed and/or applied in Europe. It points out, which indices are applicable for different use cases in science and industry in high latitudes and guides users to find the appropriate index for their purposes.
10:15	The ionospheric irregularities climatology over Svalbard from solar cycle 23	Spogli, L et al.	Oral
	Luca Spogli[1,2], Giorgiana De Franceschi[1], Lucilla Alfonsi[1], Vincenzo Romano[1,2], Claudio Cesaroni[1], Ingrid Hunstad[1]
	[1] Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome (Italy), [2] SpacEarth Technology, Via di Vigna Murata 605, 00143 Rome (Italy)
	The paper presents an unprecedented description of the climatology of ionospheric irregularities over the Arctic derived from the longest Global Navigation Satellite Systems data series ever collected for this specific aim. Two TEC and Scintillation Monitor Receivers are working at Ny-Ålesund (Svalbard, NO), the first of which has been installed in late September 2003. They sample the L1 and L2 signals at 50 Hz from all the GPS satellites in view. The receivers monitor an area of about 600 km radius that includes the auroral and the cap regions in the European longitudinal sector. The length of the data series and the privileged site of observation allow describing the Arctic ionosphere along about two solar cycles, from the descending phase of cycle 23 to almost the end of cycle 24. Our analysis results into a detailed assessment of the long-term behaviour of the ionosphere under solar maximum and solar minimum conditions, including several periods of perturbed ionospheric weather caused by unfavourable helio-geophysical conditions. To contribute to the efforts addressed to disentangle the diffractive (stochastic) from the refractive (deterministic) effects induced by the ionosphere on the GNSS signals , we have tested the use of different cut-off frequencies to look for the best choice to achieve similar behaviour of the \sigma_{\phi} and S4 indices occurrence over 1 year of data. Since November 2015, a multi-constellation GNSS receiver has been deployed in Ny-Ålesund, providing the opportunity to perform the ionospheric climatology from Galileo signals. The high degree of unpredictability of the polar and auroral scintillations by global models makes a detailed climatological description of the ionosphere at L-band over at least one solar cycle very challenging. Thus, the results of our regional assessment offer realistic features of the high latitude ionosphere that can substantially contribute to the necessary improvements of forecasting models, providing a broad spectrum of ionospheric reactions to different space weather conditions.

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