Geomagnetic storms significantly disturb the upper atmosphere and ionosphere. They cause relatively large increase of atmospheric density in thermosphere and, thus, higher drag for satellites orbiting below 2000 km of altitude. This effect was responsible for recent loss of 49 Starlink satellites, when this effect was underestimated during their launch. Geomagnetic storms can substantially affect also the GPS/GNSS signal propagation and their applications, e.g. positioning.
Geomagnetic storms have two different origins – they are excited either by the Coronal mass ejections (CMEs), or by the Co-rotating interaction regions/High speed solar wind streams (CIR/HSSWS). The former are stronger but shorter and their effects have been broadly studied. The latter are typically medium or weak storms but of longer duration. They have been studied relatively less, even though sometimes due to their longer duration they deposit more energy into the upper atmosphere than the CME-originated storms.
Our task in the Geohazards project is to study impact of CIR/HSSWS on the ionosphere and GPS/GNSS signal propagation and their applications including positioning. As the first step and the first deliverable of the project, the Catalogue of CIR/HSSWS-induced geomagnetic storms with limited atmospheric influences (https://doi.org/10.6084/m9.figshare.27919077.v1) has been created. It consists of over two hundred storms with indicated geomagnetic activity in the period of 2016-2023. Moreover, this dataset is very application-specific as it provides filtered set including only the storms without significant tropospheric activity over Central European region or sudden stratospheric warmings (SSW), allowing separate analysis of geomagnetic storms effects on ionosphere or directly on technological systems which were clearly caused by CIR-/HSSWS and not by SSW or various tropospheric events like convection associated with frontal passages.
Jan Laštovička, Jaroslav Urbář
