Global Assimilation of Ionospheric Measurements‐Gauss Markov model: Improved specifications with multiple data types

Abstract

The Earth's ionosphere is a highly dynamic region that is almost constantly in a state of flux. Solar radiation, geomagnetic activity, chemical reactions, and natural dynamics all act to perturb the state of the ionosphere. The ionosphere changes on time scales of hours to days, with the fine-scale ionospheric structures that are frequently observed lacking in global physics-based models due to time step and spatial resolution constraints. To properly specify the ionosphere, data are needed, thus data assimilation. The Utah State University Global Assimilation of Ionospheric Measurements-Gauss Markov (GAIM-GM) model uses a data assimilation method to correct a physics-based model of the ionosphere using five different data types, divided into nine different data sources. Multiple data types are necessary because the data from any individual data source will not be sufficient for global reconstructions. The GAIM-GM specification (in real time) can then be used to correct for ionospheric propagation delays, thereby improving geolocation and communications. The focus here is to show the quantitative effects that multiple data types have on GAIM-GM ionospheric specifications for a relatively quiet day (19 April) in 2012.

The COSMIC/FORMOSAT-3 Radio Occultation Mission after 12 Years: Accomplishments, Remaining Challenges, and Potential Impacts of COSMIC-2

“…This is primarily due to the fact that RO provides information on the ionosphere profile shape as well as providing observations in regions where other ionosphere observations are notoriously sparse, such as over the ocean. Using data denial experiments, the influence of RO observations on the global reconstruction of the ionosphere was investigated by Gardner et al (2014) and Schunk et al (2016) in the Utah State University Global Assimilation of Ionospheric Measurements (GAIM) data assimilation model. TEC changes of up to 40% occur due to inclusion of the RO data (Fig.…”

An improved inversion for FORMOSAT‐3/COSMIC ionosphere electron density profiles

“…Currently, the UCAR CDAAC ionosphere observations include the line of sight integrated absolute total electron content (TEC) and vertical electron density profiles that are obtained using the Abel inversion [ Yue et al , ]. Though COSMIC absolute TEC data have been used for scientific studies, they are primarily used in ionospheric data assimilation [ Komjathy et al , ; Yue et al , ; Gardner et al , ]. The majority of scientific studies are based on the COSMIC vertical electron density profiles.…”

Modeling the Midlatitude Ionosphere Storm‐Enhanced Density Distribution With a Data Assimilation Model

“…The GAIM‐GM model (Gardner, Schunk, Scherliess, Zhu, & Sojka, ; Gardner, Schunk, Scherliess, Sojka, & Zhu, ; Scherliess et al, , , , ; Schunk et al, , , , ) uses a physics‐based global ionosphere model and a Kalman filter as a basis for assimilating a diverse set of measurements. The ionosphere model is the Ionosphere Forecast Model (IFM), which covers the E region, F region, and topside ionosphere up to 1,500 km and takes account of five ion species (NO + , O 2 + , N 2 + , O + , and H + ).…”