[G06-4] Ionosphere and space weather II

[G06-4-04] Remote sensing of ionospheric TEC using GNSS observations in relation to space weather events and seismic activity in Bosnia and Herzegovina

^○Randa Natras^{1, 2}, Medzida Mulic² (1.Department of Urban Planning, Construction, Cadastre and Property Affairs, Municipality of Travnik, Travnik, Bosnia and Herzegovina, 2.Department of Geodesy, Faculty of Civil Engineering, University of Sarajevo, Sarajevo, Bosnia and Herzegovina)

Radio signals on their way from Global Navigation Satellite Systems (GNSS) to receiver on the Earth pass through various layers of atmosphere where ionosphere has major influence on their propagation, which affects accuracy of positioning and navigation. Monitoring of ionosphere above Bosnia and Herzegovina was conducted using European Permanent Network (EPN) station SRJV in Sarajevo by investigating total electrons content (TEC) variability with possible causes of its sudden variations, such as due to space weather and seismic activities. Day to day variability, seasonal variations, solar activity dependence and long term TEC trends were investigated for three years (2014 – 2016) from solar maximum to its next minimum in the solar cycle 24. For statistical analysis lower and upper bounds were determined by 15-day medians prior and after TEC anomaly ± 2*standard deviation. Results were combined with data of x-ray flux from Geostationary Operational Environmental Satellites, magnetic activity indices (Kp Ap Dst), observations of sudden ionospheric disturbances using SuperSID monitor. Transition of solar cycle from its maximum to its minimum is evident in decreasing trend of TEC from 2014 to 2017. Although some patterns of TEC variability could be observed, sudden anomalies caused major disturbances in ionosphere mostly due to space weather. The strongest geomagnetic storm (Kpmax=8-, Ap=108) in current solar cycle (17/03/2015) increased TEC values for near 60% from monthly median and than decreased to 40% in following days. Anomalous TECs were investigated for seismic activity of medium intensity (4<M<5). TEC anomalies prior earthquakes were mainly caused by gap in data and effects of space weather, but the rest of anomalies might be connected to seismic activities, such as negative anomalies to 5 TECU under lower bound observed on the day before and few days after the earthquake with epicenter 13km far from EPN station SRJV, which requires further investigations.