Description

Severe space weather events have the potential to heavily affect humanity and life on Earth. Even weaker events could be dangerous to humans in space, such as astronauts serving on the International Space Station. Expensive satellite missions and space crafts may be damaged and rendered useless by solar storms. Hence, the understanding and monitoring of space weather events is nowadays of great importance and the goal of this joint working group.

Several space geodetic techniques are capable of measuring effects caused by space weather events. Most notably, space weather events cause ionospheric disturbances that can be detected and monitored thanks to estimates of the vertical total electron content (VTEC) or the electron density (Ne) of the ionosphere. Various space geodetic observation techniques, in particular GNSS, satellite altimetry, DORIS, radio occultations (RO) and VLBI are capable of determining ionospheric key parameters, namely VTEC or Ne. For the monitoring of space weather events, low latency data availability is of great importance, ideally in real time (RT) or near real time (NRT), to enable triggering alerts. At present, however, only GNSS is greatly suited for this task. The use of the other techniques is still restricted or even impossible, in particular due to their latencies of hours (altimetry) or even days (RO, DORIS, VLBI).

JWG 3 will investigate different approaches to monitor space weather events using the data from different space geodetic techniques and, in particular, combinations thereof. Simulations will be beneficial to identify the contribution of different techniques and prepare for the analysis of real data. Different strategies for the combination of data will be investigated, in particular the weighting of estimates from different techniques in order to increase the performance and reliability of the combined estimates. Different algorithms for the detection and prediction of space weather events will also be explored or gathered from existing providers.

Furthermore, the geodetic measurement of the ionospheric electron density will be complemented by direct observations of the solar corona, where solar storms originate. Space crafts like SOHO or ACE have monitored the solar corona and the solar wind for decades and will be beneficial, together with data from other space crafts like SDO, in assessing the performance of geodetic observations of space weather events. Data from Parker Solar Probe, which will allow even greater insights through very close approaches to the Sun, has just recently been made publicly available. Geodetic VLBI is also capable of measuring the electron density of the solar corona when observing targets angularly close to the Sun and might be useful for comparisons. Other solar-related satellite missions such as Stereo, DSCOVR, GOES, etc. provide valuable information on solar radiation, particle precipitation, magnetic field variations, among other parameters. The combination and joint evaluation of these data sets with the measurements of space geodetic observation techniques is still a great challenge. Other indications for solar activity - such as the F10.7 index on solar radio flux, SOLERA as EUV proxy or rate of Global Electron Content (dGEC), provide additional opportunities for comparisons and validation. Through these investigations, we will gain a better understanding of space weather events and their effect on Earth’s atmosphere and near-Earth environment.