The term space weather indicates physical processes and phenomena in space caused by the radiation of energy mainly from the Sun. Solar and geomagnetic storms can cause disturbances in positioning, navigation and communication; coronal mass ejections (CME) can affect serious disturbances and in extreme cases damages or even destruction of modern infrastructure. The ionosphere and the thermosphere are parts of a physically coupled systems ranging from the Earth surface to the Sun including the magnetosphere and the lower atmosphere. Therefore, conducting detailed investigations on governing processes in the solar-terrestrial environment have key importance to understand the spatial and temporal variations of ionospheric and thermospheric key parameters such as the total electron content (TEC) and the plasma density of the ionosphere, as well as the thermospheric neutral density, which are influencing the orbits of Low-Earth orbiting (LEO) satellites. To address all these interrelations and impacts, the Global Geodetic Observing System (GGOS) Focus Area on Geodetic Space Weather Research was implemented into the structure of the International Association of Geodesy (IAG).

This session will address recent progress, current understanding, and future challenges of thermospheric and ionospheric research including the coupling processes. Special emphasise is laid on the modelling and forecasting of space weather time series, e.g. EUV-, X-ray radiation and CMEs, and their impact on VTEC and electron density. We encourage further contributions to the dynamo electric field, the variations of neutral and ion compositions on the bottom and top side of the ionosphere, atmospheric gravity waves and TIDs. Furthermore, we appreciate contributions on the wind dynamo, electrodynamics and disturbances, including plasma drift, equatorial spread F, plasma bubbles, and resultant scintillation.

Another main topic is global and regional high-resolution and high-precision modelling of VTEC and the electron density based on empirical, analytical or physical data assimilation approaches, which are designed for post-processing or (near) real-time purposes.

Geodesy contributes to Atmospheric Science by providing some of the Essential Climate Variables of the Global Climate Observing System. Water vapor is under-sampled in the current meteorological and climate observing systems. Obtaining and exploiting more high-quality humidity observations is essential to weather forecasting and climate monitoring. The production, exploitation and evaluation of operational GNSS-Meteorology for weather forecasting is well established in Europe due to 20+ years of cooperation between the geodetic community and the national met services. Advancements in NWP models to improve forecasting of extreme precipitation require GNSS troposphere products with a higher resolution in space and shorter delivery times than are currently in use. Homogeneously reprocessed GNSS data have high potential for monitoring water vapor climatic trends and variability. With shortening orbit repeat periods, SAR measurements are a new source of information to improve NWP models. Using NWP data within real-time processing of GNSS observations can initialize PPP algorithms, shortening convergence times and improving positioning. GNSS signals can be used for L-band remote sensing when Earth-surface reflected signals are considered. GNSS-reflectometry contributes to environmental monitoring with estimates of soil moisture, snow depth, ocean wind speed, sea ice concentration and has the potential to be used to retrieve near-surface water vapor.
We welcome, but not limit, contributions on:
•Estimates of the neutral atmosphere using ground-based and space-based geodetic data, use of those estimates in weather forecasting and climate monitoring
•Multi-GNSS and multi-instruments approaches to retrieve and inter-compare tropospheric parameters
•Real-Time and reprocessed tropospheric products for now-casting, forecasting and climate
•Assimilation of GNSS tropospheric products in NWP and in climate reanalysis
•Production of SAR-based tropospheric parameters and use of them in NWP
•Methods for homogenization of long-term GNSS tropospheric products
•Studies of the delay properties of the GNSS signals for propagation experiments
•Usage of NWP data in GNSS data processing
•Techniques on retrieval of soil moisture from GNSS observations and of ground-atmosphere boundary interactions
•Estimates and methods using GNSS reflectometry for the detection and characterization of sea ice
•Usage of satellite gravity observations for studying the atmospheric water cycle.