Speaker
Description
RISER – Radio Investigations for Space Environment Research – is a £3.7M NERC-funded Large Environment 5-Year Project addressing the full chain of space weather phenomena from the Sun to the Earth. It investigates how regular radio observations taken using the LOw Frequency ARray (LOFAR) can be used for continuous, accurate tracking of inner-heliospheric and ionospheric plasma structures, combined with magnetospheric modelling, and incorporated into space weather forecast models leading to more precise and advanced forecasts of space weather and its impacts.
Since March 2025 the LOFAR-UK Rawlings Array has been used full time for RISER measurements, recording over 100 observations per day of interplanetary scintillation (IPS), distributed across the inner heliosphere, which are subsequently analysed to produce estimates of velocity and ‘g-level’, a measure of the strength of scintillation, related to density. These analyses are joined with the extant ISEE, Japan, IPS data available in near real time, supplemented by Murchison Widefield Array (MWA, western Australia) observations, thus covering different times and Earth longitudes, to input into tomographic reconstructions to visualise and track conditions throughout the inner heliosphere. Such a high number of observations offers the possibility of increasing the resolution of these tomographic reconstructions for greater accuracy in the visualisation, tracking, and resulting predictions.
The reconstructions are also used as input into an Enlil solar wind model variant under test at the Met Office. An important recent activity has been to build a workflow to automate the process of feeding the IPS data into the tomography code and then coupling the resultant tomographic reconstructions to the Enlil code. This is highly important for efficient exploitation of the IPS observations, but also key for the use of IPS observations in any upgraded near real time operational solar wind forecast system in the future.
This period has encompassed increased levels of activity with CMEs and high-speed streams affecting the magnetosphere-ionosphere system, occasionally pushing the auroral oval southwards to more middle latitudes. A vital component of the RISER project is to link the heliospheric conditions at Earth via magnetospheric modelling to conditions in the ionosphere. Observations of the strong radio source Cassiopeia A are taken overnight by the LOFAR-UK Rawlings Array, along with single-frequency all-sky imaging data (since May) to measure broadband ionospheric scintillation and refractive effects. The frequency dependence of scintillation observations makes them sensitive to ionospheric structures occurring over different spatial scales, while refractive effects are the result of larger-scale structure. When combined with independent observations (such as from satellites), this enables the reconstruction of ionospheric structures forming and occurring during the diverse space weather conditions occurring over this time.
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