Vida Žigman, UNG, Nova Gorica,Slovenia ESWW10 Antwerp, November 2013 Modelling flare induced ionization enhancements of the lower ionosphere with LYRA data relating Space LYRA – Earth VLF data Guest Investigator Program Fourth Call:Sep Jun 2014 ESWW10 / PROBA2 splinter Davorka Grubor, UB, Belgrade, Serbia Craig Rodger, Department of Physics, University of Otago, Dunedin, New Zealand Mark Clilverd, British Antarctic Survey, Cambridge,UK

Understand Impact of Flares! On the Lower Ionosphere km height Observations of the effects of Solar X-ray flares from Earth – VLF transmission Correlation: VLF data - space based measurements Can we exploit LYRA data? How to combine data and model: N(t,h), LWPM (some) RESULTS – 90 km height Prospects OUTLINE Objectives:

DATA: LYRA ch2-4(Zr); 6 – 20 nm+X-ray(< 2 nm) (SWAP ?) GOES ( nm ) Flare classification SPACE : Solar irradiance GOES

2011_02_28_M1.1 Dammasch et al COSPAR Dominique et al Solar Physics, DOI: The LYRA Instrument Onboard PROBA2: Description and In-Flight Performance Characteristics of the Lyra Irradiance: Lyra peaks after GOES Lyra descends slower than GOES LYRA - 4 years in orbit

DATA: EARTH : VLF data - AMPLITUDE & PHASE on different sunlit paths from receivers R x Belgrade IP VLF Observatory – Belgrade University Casey and Scott Base stations, Antarctica – Otago University, Dunedin NZ BAS, Cambridge, UK

raypath trace great circle EARTH reflection point D region Earth-ionosphere waveguide T (transmitter) R (receiver) Radiowave propagation (Supported by NOSC LWPC) Solar Lyman Alpha (121.6 nm) during flares: Solar X-rays emit VLF f < 30 kHz Transmitter: NWC/19.8 kHz Receiver: Belgrade AbsPAL On Earth: D-region measure AMPLITUDE & PHASE DISTURBANCES

2011_02_18 NWC - Bgd OBSERVATIONS: All data in 1 min cadence NWC – Bgd km

q( t ) = k I (t) MODELLING: time dependence! Irradiance I (t) 2012_03_07 FROM LYRA! From Goes AMP & PHA Time delay! NPM_SB_ _2057_M1.5

N [m -3 ], I X x 10 16, I L x [Wm -2 ] Time UT Electron density at 90 km height from AMPLITUDE time delay GOES (2, 1.92) LYRA (1, 0.79) N max [m -3] LYRA I max 1012 UT, 3.35 mW/m 2 [ min] NWC- Bgd _1011_M

2013_05_13 NPM – Scott Base OBSERVATIONS: Lll L

ScottScott Gde je NPM? Casey Scott B. NWC/19.8 kHz NPM/21.4 kHz NPM- Scott Base km

2012_03_07_ NPM-Casey

2012_03_07_ NPM-Scott Base

N [m -3 ], I X x 10 15, I L x [Wm -2 ] Time UT _0115_ NPM-Casey X1.4 NPM_Scott Base ( , ) m -3 Overall: at 90 km 0

2013_10_28_ NPM-Scott Base

N [m -3 ], I X x 10 16, I L x [Wm -2 ] Time UT NPM-Scott Base _2057_M1.5 Electron density at 90 km height from AMPLITUDE & PHASE time delay GOES (2.5, 2.32) LYRA (0.5, 0.52) AMP GOES (3.5, 3.30) LYRA (1.5, 1.58) PHA LYRA I max 2059 UT, 1.78 mW/m 2 N max [m -3] [ min]

Summary LYRA data can be used to assess the flare enhanced electron density at the ceiling of the D-region - 90 km. N max, N(t) N(t) according to LYRA decreases slower than according to GOES. The predictions of the maximal flare induced electron density at 90 km height are in reasonabe agreement. M1.5 M6.6 X1.4 N max [m.3 ] ( , ) ( , ) Prospects: Can the lower ionization efficiency be compensated by higher irradiance ? Assessment with Long Wavelength Propagation Capability LWPC (NOSC)

Thanks to Proba2 Science Centre D. Berghmans M. Dominique LYRA Team M. West NOAA/SWPC Antarctica logistic providers The Audience ! ESWW10 Antwerp, November 2013