Characteristics of Large Scale Travelling Ionospheric Disturbances - PowerPoint PPT Presentation

Characteristics of Large Scale Travelling Ionospheric Disturbances Exploiting Ground-Based Ionograms, GPS-TEC and 3D Electron Density Distribution Maps Anna Belehaki, Ioanna Tsagouri (NOA, Greece) Ivan Kutiev, Pencho Marinov (BAS, Bulgaria)

Large Scale Travelling Ionospheric Disturbances (LSTIDs) are recognized as ionospheric manifestations of the passage of AGWs that are generated at high latitudes by the energy input from the magnetosphere to the auroral ionosphere. (Hunsucker, 1982; Hocke and Schlegel, 1996) • Horizontal scale > 1000 to 3500 km • Period ~ 30 to 180 min • Mean horizontal velocity ~ 300 to 1000 m/s (Afraimovich et al., 1998; 2002; Tsugawa et al., 2004; Ding et al., 2007) • Damping and growth rates of LSTIDs are correlated with upward and downward propagating AGWs (Tsugawa et al., 2004)

Identification and tracking of TIDs Afraimovich method: calculations of spatial and temporal variations of TEC Method based on 2D maps of TEC perturbation (ex. Ding et al., 2007) measured at three spaced GPS receivers

Methodology • Identification of the onset time, polar and auroral magnetograms inspection • Indications from Digisondes: ionograms + electron density variation with height • Indications from the slant TEC (STEC) variation extracted from GPS receivers • Analysis of the electron density model output (TaD model)

0430 UT Main onsets: 0200 @ IQA 0220 @ FCC 0300 @ YKC 0430 @ IQA

IMAGE array 0105 0410

IMAGE array 0105 0410

Onset time Two main indications of westward electrojet intensification were observed: • at 0200UT and 0430 from the Canadian magnetometers • at 0105UT and 0410 from the Scandinavian magnetometers (local time in Europe is close to midnight) Conclusion: The European chain of Digisondes should see first the disturbance (high probability of spread-F, the nighttime indication of TID)

Monitoring network at the 12°-15° meridian GPS receiver Digisonde

Pruhonice, 50°N 15 min sampling Sounder: DPS4D Settings: 50kHz, 2.5km Dourbes, 50.1°N 5 min sampling Sounder: DPS4D Settings: 45kHz, 2.5 km

Rome, 50°N 15 min sampling Sounder: DPS4 Settings: 50kHz, 2.5km Ebro, 50.1°N 5 min sampling Sounder: DPS4D Settings: 25kHz, 2.5km

Quiet Day Storm Days: 7 and 8 March 2012 – sTEC(GPS) perturbations

The LSTID amplitude depends on the STEC filtering method STEC Background: 1 hr avrg STEC Background: 3 hr avrg

TaD: the Topside Sounders Model – assisted Digisonde Present profiling technique combines: - a core empirical model (TSM) providing the topside scale height and upper transition (O + - H + ) height, - a profiler (TSMP) providing the shape of the vertical electron density profile in the topside and plasmasphere as a sum of O + , H + , and He + partial distributions, - a TSM-assisted Digisonde 1200 (TaD) profiler ingesting measured profile Digisonde-derived parameters 1000 peak altitude, density, and Altitude, km topside scale height into 800 transition height, Ne=2n(O+) TSMP, allowing real-time update of TSMP. O+ profile 600 vertical O+ scale height 400 10 11 12 13 14 ln (Ne)

Juliusruh – TaD signatures 7 March 2012 8 March 2012 0 6 12 18 24 0 6 12 18 24 0 6 12 18 24 0 6 12 18 24

Pruhonice-TaD signatures 0 6 12 18 24 0 6 12 18 24 0 6 12 18 24 0 6 12 18 24

Dourbes-TaD signatures 0 6 12 18 24 0 6 12 18 24

Rome-TaD signatures 15 min resolution 0 6 12 18 24 0 6 12 18 24 30 sec resolution

Ebro-TaD signatures 0 6 12 18 24 0 6 12 18 24

40 60 orm 1 35 TEC 55 30 25 Latitude 50 20 45 15 10 40 5 35 0 0 0.5 1 1.5 2 2.5 3 3.5 4 Days from 00 UT on 7 March 2012 20 800 SW pressure pressure speed 600 speed 10 400 0 200 20 10 By, Bz 0 -10 By Bz -20 15 12 Kp Kp, PC 9 PC 6 3 0 -3 0 Dst -50 -100 AE 1200 AU 800 AE, AU, AL AL 400 0 -400 -800 -1200 -1600 -2000 07 08 09 10 11 Days from 00 UT on 07 March 2012 TECr

Conclusions Digisondes: the inspection of contour plots of true height, and of ionograms provide an indication of the horizontal and vertical extent of the area affected by the LSTIDs – DPS4Ds with high cadence (5min) of measurements provide observations of best quality GPS receivers : the 30 sec analysis of dSTEC from a network of receivers provide information the duration, the amplitude, the propagation direction, the growth and the damping of LSTIDs – need to confirm how these are affected by the filtering TaD reconstruction model : it runs operationally in DIAS and provides 3D EDD and TEC maps at 15 min sampling using Digisonde derived parameters at the peak height. This preliminary analysis shows that the model is sensitive to LSTIDs , with indications comparable to those obtained from GPS receivers even with 15 min measurements. TaD model can reproduce the general pattern of ionospheric variations due to LSTIDs – although there are discrepancies in the amplitude calculations comparing to the dSTEC results and this needs to be carefully investigated.

Thank you for your attention! Acknowledgements are due to: EOARD, GIRO network and to Luigi Ciraolo for making us available the software routine that converts RINEX to sTEC and vTEC

TaD model results: Pruhonice

TaD model results: Dourbes

TaD model results: Ebro

Input Parameters Code Output Month, LT, glat, f10.7, Kp TSM: Topside Empirical functions of Sounders Model H T : topside scale height Analytical approximation of h T : transition height Alouette, ISIS-1,-2 topside R T : ratio H T /h T profiles (Bilitza, 2001) H T ( ≡ H O+ ), h T , H m , N m and TSMP: Topside Empirical functions of H P : plasmaspheric scale height ( ≡ H H+ ) glat Sounders Model H P = H T (9 cos 2 glat +4) Profiler Analytical approximation of Ne : electron density profile in the topside ionosphere ISIS-1 topside profiles to and plasmasphere model plasmaspheric scale | h h |  h − h   −  height Ne = N ( h ) + gN ( h ) exp  − T  + ( 1 − g ) N ( h ) exp  − T      T T O + O + Hp O + 4 H     T  1 h hm h hm   − −    N O ( h ) Nm exp 1 exp and = − + −       + 2 Hm Hm       g is the ratio N H + / N O + at h T h h | h h |  −   −  Digisonde parameters at TaD: TSM-assisted Ne N ( h ) gN ( h ) exp ( 1 g ) N ( h ) exp  T  = +  − T  + − −     T T + + Hp + skH O O O     the height of maximum Digisonde Profiler m Calculation of the actual density ( hmF2 , foF2 , H m ) where s = H He+ / kH m profile over each Digisonde and vTEC (GNSS) at the k is the correction parameter that converts H m (the location to update TSMP Digisonde location neutral scale height) to make it compliant with H T with current Digisonde and TEC (GNSS) parameters The integral of the Ne profile can be adjusted to the measured vTEC by varying solely the correction parameter k