What is ESIR?

ESIR is a new approach to automated ionogram scaling. It uses a combination of physics-based modeling and knowledge-based pattern recognition techniques to extract traditional ionospheric parameters such as f_oF₂ and h_mF₂, and it can also generate electron density profiles (EDPs.) ESIR provides quality and uncertainty indications for these parameters, which enable the user to decide how much confidence to place in the scaled parameters. ESIR is specifically intended to provide suitable inputs to assimilative ionospheric models such as GAIM, but its products can be used for a variety of applications. ESIR development has focused on mid- and low-latitude ionograms.

Ionograms in various formats are converted to a standard ESIR file for analysis. The heart of ESIR is ensemble analysis using differing sets of assumptions. If all analyses are in good agreement, they provide the statistics for estimating the error associated with the various parameters. However, if the analyses yield wildly different results, or return flags indicating problems such as severe spread F contamination, then the analysis may be aborted.

Supported Ionosondes

ESIR is designed to work with any vertical incidence ionosonde that produces a conventional virtual height vs. frequency ionogram in the HF range. Several versions have been developed for particular types of hardware.

The basic version does not require hardware separation of extraordinary (X) and ordinary (O ) traces. Without this information, there may be ambiguities in identifying traces in some cases, so confidence is accordingly lower.

An improved version that makes full use of hardware X- and O-traces has been developed that gives more reliable estimates of the desired ionogram parameters.

In either case, the geographical coordinates of the sounder and the time of the sounding are required for modeling purposes. ESIR also uses the coordinates to determine the local ionospheric magnetic field needed for X/O-trace analysis.

The first step in ESIR processing is to convert the ionogram from the sounder-specific format into a standardized ESIR file with well-defined variables and attributes. The ESIR file is then used by various modules for analysis and scaling. Outputs are generally produced in plain text format, though other formats such as netCDF may also be generated for user applications.

ESIR conversion routines have been developed for Vertical Incidence Pulsed Ionospheric Radars (VIPIRs), DISS Digisondes, the Canadian Advanced Digital Ionosonde (CADI), and for ionograms digitized from film archives or other graphic formats.

Contact Information

For more information, contact:

Space Environment Corporation

221 N. Spring Creek Parkway, Suite A

Providence, UT 84332-9791

sec@spacenv.com  (435) 752-6567