Real time reconstruction of 3-D electron density distribution over Europe with TaD profiler Ivan Kutiev 1,2, Pencho Marinov 1, Anna Belehaki 2 1 Bulgarian Academy of Sciences 2 National Observatory of Athens

The core Topside Sounder Model (TSM) and TSM profiler (TSMP) TSM (Topside Sounder Model) provids - topside scale height H T, - upper (O + -H + ) transition height h T, - (scale height)/(transition height) ratio R T TSMP (Topside Sounder Model Profiler) provides the shape of the vertical electron density (Ne) profile in topside ionosphere and plasmasphere as a sum of O + and H + individual profiles. When the density and height of the F layer peak are specified, TSMP defines the Ne profile. Hp HTHT

TSMP-assisted Digisonde profiler (TaD) In the topside: TSMP provides the shape of Ne profile At F layer peak: Digisonde provides NmF2, and hmF2 The new coupled profiler is named TSMP-assisted Digisonde (TaD) profiler. TaD now provides electron density profiles in topside ionosphere and plasmasphere at the time of Digisonde sounding, e.g. in real time.

Digisonde and TaD topside profiles Digisonde topside profile is expressed by the α-Chapman formula. At higher altitudes the profile decreases with a scale height 2Hm (Hm is the neutral scale height). The O + scale height H T, provided by TaD is approximately 1.25 times larger than Hm.

Further improvement of TaD Modeling the He + profile around transition height h T Modeling the Hp/H T ratio as a function of geomagnetic latitude, month, local time, and O + density at transition height h T (using ISIS-1 topside sounder Ne profiles) Profile parameters Hp and h T are presented by their ratios with H T, so the shape of the whole TaD profile is made dependent on H T only. Adjustment of the integral of TaD profile with measured GNSS- TEC.

Using TaD profiler in reconstruction of 3-D electron density distribution (EDD) over Europe Concept: Produce TaD Ne profiles over the Digisonde stations of the DIAS ionosonde network, adjusted by TEC values extracted from the ROB GNSS-TEC maps. For the same mapping area calculate the profile parameters: NmF2, hmF2, H T, h T, and Hp at all grid nodes (1˚x1˚) by using the Polyweight spatial interpolation procedure. Produce TaD profiles at grid nodes. Develop a procedure calculating electron density at any point of the 3-D space by interpolating between the proper profile values at grid nodes.

DIAS ionosonde network European DIAS (Digital Upper Atmosphere Server) network consists of 8 Digisonde stations. They provide foF2, hmF2, and bottomside Ne profile every 15 min. ( Mapping area is confined to (-10˚,25˚)E and (35˚,60˚)N to comply with the GNSS-TEC maps provided by Royal Observatory of Belgium (ROB)

Maps of TaD profile parameters Maps are produced by Polyweight interpolation procedure, after the TaD profiles were calculated and adjusted with GNSS-TEC values at each grid node (1˚x1˚) geographic coordinates.

Electron density maps at fixed altitudes Ne distribution at fixed heights is produced by using TaD profiles at the grid nodes. Ne profiles below hmF2 are provided by Digisonde software. Level ranges are different for the different heights.

Vertical slices from the 3-D EDD

Vertical Ne profiles at -10˚E, 35˚N

Vertical Ne profiles at 25˚E, 60˚N

Ne profile along the raypath (-10˚,35˚) and (25˚,60˚)

Ne profile along the raypath (25˚,35˚) and (-10˚,60˚)

Conclusion On the basis of TaD profiling technique, a new method is developed for reconstruction of the 3-D electron density distribution (EDD) over Europe in real time. Respective software allows obtaining the EDD along arbitrary raypaths within the mapping area. The software is planned to be implemented in DIAS system and consequently to be used to upgrade the products streaming from DIAS to the ESA Space Situational Awareness Space Weather Services.

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