Ionospheric Data Assimilation Three‐Dimensional (IDA3D): A global, multisensor, electron density specification algorithm

Abstract

[1] With the advent of the Global Positioning System (GPS) measurements (from both ground-based and satellite-based receivers), the number of available ionospheric measurements has dramatically increased. Total electron content (TEC) measurements from GPS instruments augment observations from more traditional ionospheric instruments like ionospheric sounders and Langmuir probes. This volume of data creates both an opportunity and a need for the observations to be collected into coherent synoptic scale maps. This paper describes the Ionospheric Data Assimilation Three-Dimensional (IDA3D), an ionospheric objective analysis algorithm. IDA3D uses a three-dimensional variational data assimilation technique (3DVAR), similar to those used in meteorology. IDA3D incorporates available data, the associated data error covariances, a reasonable background specification, and the expected background error covariance into a coherent specification on a global grid. It is capable of incorporating most electron density related measurements including GPS-TEC measurements, low-Earth-orbiting ''beacon'' TEC, and electron density measurements from radars and satellites. At present, the background specification is based upon empirical ionospheric models, but IDA3D is capable of using any global ionospheric specification as a background. In its basic form, IDA3D produces a spatial analysis of the electron density distribution at a specified time. A time series of these specifications can be created using past specifications to determine the background for the current analysis. IDA3D specifications are able to reproduce dynamic features of electron density, including the movement of the auroral boundary and the strength of the trough region.

Tomography of the ionospheric electron density with geostatistical inversion

“…Bust et al (2004) suggested the separation of the spatial covariance model into horizontal and vertical components to take the geometric anisotropy of the ionosphere, i.e., directionally dependent correlation lengths, into account. Yue et al (2007) and Shim et al (2008) confirmed this approach with the analysis of GPS and incoherent scatter radar observations revealing different correlation lengths in latitude, longitude and height direction.…”

“…However, EDAM also deals with ionospheric radio occultation (IRO), ionosonde data and in situ electron density measurements; see Angling et al (2008). Bust et al (2004) developed a similar approach, the Ionospheric Data Assimilation ThreeDimensional (IDA3-D) technique based on 3-D variational data assimilation. Both EDAM and IDA3-D apply an exponential time covariance model to forecast the electron density state vector and its covariance matrix from one time step to the next.…”

A multiresolution inversion for imaging the ionosphere

“…A multiinput tomographic algorithm, named as Multi‐Instrument Data Analysis System (MIDAS) was built to enable the ingestion of multiple data sources (e.g., ground‐based GPS data, Low Earth Orbiter‐based GPS data, and ionosonde measurements) into the inversion to produce images of ionospheric electron density [ Mitchell and Spencer , 2003]. Bust et al [2004] developed an ionospheric imaging technique based on data assimilations—Ionospheric Data Assimilation Three‐Dimensional. A comprehensive review of ionospheric imaging is given in Bust and Mitchell [2008].…”

First storm‐time plasma velocity estimates from high‐resolution ionospheric data assimilation

“…In particular, IDA4D has been used to investigate the ionospheric response to major geomagnetic storms [Bust and Mitchell, 2008;Bust and Crowley, 2008], including the formation and evolution of SED. A complete mathematical derivation of the IDA4D algorithm can be found in Bust et al [2000Bust et al [ , 2004 and Bust and Datta-Barua [2012a]. One of the powerful features of IDA4D is that the inversion grid is user selectable and need not be regular.…”

“…[11] Ionospheric Data Assimilation Four-Dimensional (IDA4D) [Bust et al, 2000] is a continuous-time, threedimensional imaging algorithm [Bust et al, 2004] routinely used to produce 4-D (time and space) ionospheric electron density specifications for various science investigations Bust et al, 2007;Yin et al, 2006;Crowley et al, 2006]. In particular, IDA4D has been used to investigate the ionospheric response to major geomagnetic storms [Bust and Mitchell, 2008;Bust and Crowley, 2008], including the formation and evolution of SED.…”