The low frequency array (LOFAR) is a phased array interferometer currently consisting of 13 international stations across Europe and 38 stations surrounding a central hub in the Netherlands. The instrument operates in the frequency range of ~10–240 MHz and is used for a variety of astrophysical science cases. While it is not heliophysics or space weather dedicated, a new project entitled “LOFAR for Space Weather” (LOFAR4SW) aims at designing a system upgrade to allow the entire array to observe the Sun, heliosphere, Earth’s ionosphere, and Jupiter throughout its observing window. This will allow the instrument to operate as a space weather observing platform, facilitating both space weather science and operations. Part of this design study aims to survey the existing space weather infrastructure operating at radio frequencies and show how LOFAR4SW can advance the current state-of-the-art in this field. In this paper, we survey radio instrumentation and facilities that currently operate in space weather science and/or operations, including instruments involved in solar, heliospheric, and ionospheric studies. We furthermore include an overview of the major space weather service providers in operation today and the current state-of-the-art in the radio data they use and provide routinely. The aim is to compare LOFAR4SW to the existing radio research infrastructure in space weather and show how it may advance both space weather science and operations in the radio domain in the near future.

<p>The Low Frequency Array (LOFAR) is an advanced phased-array radio-telescope system based across Europe.  It is capable of observing over a wide radio bandwidth of ~10-250 MHz at both high spatial and temporal resolutions.  LOFAR has capabilities that enable studies of many aspects of what we class as space weather (from the Sun to the Earth and afar) to be progressed beyond today’s state-of-the-art.   However, with the present setup and organisation behind the operations of the telescope, it can only be used for space-weather campaign studies with limited triggering availability.  This severely limits our ability to effectively use LOFAR to contribute to space-weather monitoring/forecast beyond its core strength of enabling world-leading scientific research.  LOFAR itself is made up of a dense core of 24 stations near Exloo in The Netherlands with an additional 14 stations spread across the northeast Netherlands.  In addition to those, there are a further 13 stations based internationally across Europe.  These international stations are, currently, six in Germany, three in northern Poland, and one each in France, Ireland, Latvia, Sweden, and the UK.  Further sites are under preparations (for example, in Italy).</p><p> </p><p>We are undertaking a Horizon 2020 (H2020) INFRADEV design study to undertake investigations into upgrading LOFAR to allow for regular space-weather science/monitoring observations in parallel with normal radio-astronomy/scientific operations.  This project is called the LOFAR For Space Weather (LOFAR4SW) project (see: http://lofar4sw.eu/).  Our work involves all aspects of scientific and engineering work along with end-user and political engagements with various stakeholders.  This is with the full recognition that space weather is a worldwide threat with varying local, regional, continent-wide impacts, and also global impacts – and hence is a global concern.</p><p> </p><p>Here, we summarise the most-recent key aspects of the LOFAR4SW progress including outputs/progress following the Detailed Design Review (DDR) that took place at ASTRON, The Netherlands, in March 2020, as well as the implementation of recommendations from the earlier Preliminary Design Review (PDR) with an outlook to the LOFAR4SW User Workshop the week following EGU 2020.  We also aim to briefly summarise a key set of the longer-term goals envisaged for LOFAR to become one of Europe’s most-comprehensive space-weather observing systems capable of shedding new light on several aspects of the space-weather system, from the Sun to the solar wind to Jupiter and Earth’s ionosphere.</p>

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<p>Space Weather (SW) research is a very important topic from the scientific, operational and civic society point of view. Knowledge of interactions in the Sun-Earth system, the physics behind observed SW phenomena, and its direct impact on modern technologies were and will be key areas of interest.  The LOFAR for Space Weather (LOFAR4SW) project aim is to prepare a novel tool which can bring new capabilities into this domain. The project is realised in the frame of a Horizon 2020 INFRADEV call.  The base for the project is the Low Frequency Array (LOFAR) - the worlds largest low frequency radio telescope, with a dense core near Exloo in The Netherlands and many stations distributed both in the Netherlands and Europe wide with baselines up to 2000 km.  The final design of LOFAR4SW will provide a full conceptual and technical description of the LOFAR upgrade, to enable simultaneous operation as a radio telescope for astronomical research as well as an infrastructure working for Space Weather studies.  In this work we present the current status of the project, including examples of the capabilities of LOFAR4SW and the project timeline as we plan for the Critical Design Review later in 2021.</p>