Feasibility study for reconstructing the spatial‐temporal structure of TIDs from high‐resolution backscatter ionograms

Over‐the‐horizon radar (OTHR) utilizes the reflective “sky wave” property of the ionosphere for high‐frequency radiowaves to illuminate targets at ranges extending to several thousand kilometers. However, the ionospheric “mirror” is not static but exhibits geographic, diurnal, seasonal, and solar cycle variations. NorthWest Research Associates has developed an ionospheric data assimilation capability called Global Positioning Satellite Ionospheric Inversion (GPSII; pronounced “gypsy”) that allows real‐time modeling of the ionospheric structure for the purpose of accurate coordinate registration (CR; OTHR geolocation). However, the ionosphere is routinely subjected to traveling ionospheric disturbances (TIDs), and the deflection of HF sky wave signals by unmodeled TIDs remains a troubling source of CR errors (tens of kilometers). Traditional OTHR tools for ionospheric sounding (vertical and backscatter ionograms) do not resolve the fine spatial structure associated with TIDs. The collection of backscatter ionograms using the full aperture of the OTHR was recently demonstrated, thus providing enhanced resolution in radar azimuth in comparison with conventional OTHR backscatter soundings that utilize only a fraction of the OTHR receiver array. Leading edges of such backscatter ionograms demonstrate prominent spatial features associated with TIDs. We investigate the feasibility of recovering TID perturbations of ionospheric electron density from high‐resolution backscatter ionograms. We incorporated a model of naturally occurring TIDs into a numerical ray tracing code that allows the generation of synthetic OTHR data. We augmented GPSII to assimilate time series of full‐aperture backscatter ionogram leading edge data. Results of the simulation show that GPSII is able to reproduce the TID structure used to generate the backscatter ionograms reasonably well.

[1]  S. V. Fridman,et al.  Reconstruction of a three‐dimensional ionosphere from backscatter and vertical ionograms measured by over‐the‐horizon radar , 1998 .

[2]  M. A. Cervera,et al.  Modeling ionospheric disturbance features in quasi‐vertically incident ionograms using 3‐D magnetoionic ray tracing and atmospheric gravity waves , 2014 .

[3]  J. Marsden,et al.  Tricubic interpolation in three dimensions , 2005 .

[4]  Mark Hausman,et al.  HiCIRF: A high‐fidelity HF channel simulation , 2012 .

[5]  Sergey V. Fridman,et al.  Inversion of backscatter ionograms and TEC data for over‐the‐horizon radar , 2012 .

[6]  S. Fridman,et al.  Generalization of ionospheric tomography on diverse data sources: Reconstruction of the three‐dimensional ionosphere from simultaneous vertical ionograms, backscatter ionograms, and total electron content data , 2001 .

[7]  L.J. Nickisch,et al.  Traveling Ionospheric Disturbance Mitigation for OTH Radar , 2007, 2007 IEEE Radar Conference.

[8]  Sergey V. Fridman,et al.  Personal‐computer‐based system for real‐time reconstruction of the three‐dimensional ionosphere using data from diverse sources , 2009 .

[9]  D. Drob,et al.  Nrlmsise-00 Empirical Model of the Atmosphere: Statistical Comparisons and Scientific Issues , 2002 .

[10]  Matthew Angling,et al.  Assimilation procedures for updating ionospheric profiles below the F2 peak , 2013 .

[11]  C. Hines.  Ionospheric Irregularities Produced by Internal Atmospheric Gravity Waves , 2013 .

[12]  E. Catmull,et al.  A CLASS OF LOCAL INTERPOLATING SPLINES , 1974 .

[13]  G. Crowley,et al.  Characteristics of traveling ionospheric disturbances observed by the TIDDBIT sounder , 2012 .

[14]  R. Jones,et al.  A Versatile Three-Dimensional Ray Tracing Computer Program for Radio Waves in the Ionosphere , 1975 .

[15]  Mark Hausman,et al.  Real‐time reconstruction of the three‐dimensional ionosphere using data from a network of GPS receivers , 2006 .

[16]  William H. Hooke,et al.  Ionospheric irregularities produced by internal atmospheric gravity waves , 1968 .