Beata Dziak-Jankowska 1 , Iwona Stanisławska 1 , Tomasz Ernst 2 , Łukasz Tomasik 1

1. Beata Dziak-Jankowska1, Iwona Stanisławska1, Tomasz Ernst2 , Łukasz Tomasik1 1 Space Research Centre PAS, ul. Bartycka 18A, Warsaw, Poland 2 Institute of Geophysics PAS, ul. Ksiecia Janusza 64, Warsaw, Poland Sixth European Space Weather Week,17.11.2009, Brugge Anadvantage of magnetic index h to show high local disturbances in ionosphere during quiet day conditions

2. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of h with ionospheric characteristics • Physics and interpretation of the results • Operational applications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

3. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

4. Indexh Magneticdriversbringessentialinput to theionosphere, so syntheticinformationgatheredinmagneticindicesisoftenused. Theypresentthequantification of theionosphericchanges. The magnetic index h was proposed by Ernst & Jankowski (2005). Sixth European Space Weather Week, 16-20 November 2009, Brugge

5. Indexh The geomagnetic data gathered within the INTERMAGNET network were applied to the simple method for separating variations of the vertical component Z into parts of external and internal origin. The main advantages of this method are its simplicity and possibility of using data from a single station for such separation. Ernst and Jankowski introduced a new coefficient characterizing deviations of the magnetic field observed in Observatories from the plane wave. This coefficient, determined by comparing amplitudes of the vertical and horizontal components' variations, has the form: Where PX, PY and PZe are the energies in the period range 240-10 800 s calculated in the time domain from selected three-hour events. The value h = 0 means that the external field can be represented by a plane wave, whereas nonzero values of hindicate a deviation from the plane wave field structure. Sixth European Space Weather Week, 16-20 November 2009, Brugge

6. The analysis was based on one-minute data recorded at each of 20 European Magnetic Observatories working in the INTERMAGNET network. Sixth European Space Weather Week, 16-20 November 2009, Brugge

7. An example of variations in the external parts of the horizontal components X and Y (based on one-minute data from the Belsk observatory) and vertical component Z from other observatories. Typical amplitude 10 nT and period equal to 1-2 h. X Y Z Z Z Z Z Z Z BEL BEL BEL LGK CLV FUR BDV HRB THY Sixth European Space Weather Week, 16-20 November 2009, Brugge

8. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

9. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

10. We chose the day 8th July 2004 for analysis. This day has a very low Kp index (0-1), which indicates very low magnetic activity, but the index h exceeds 1 (atypical value) at several stations and in some cases h exceeds 2.5 (extremely unusual value). Kp 0 0 0 0 1 0 0 0 h > 2.5 Sixth European Space Weather Week, 16-20 November 2009, Brugge

11. Kp 0 0 0 0 1 0 0 0 Sixth European Space Weather Week, 16-20 November 2009, Brugge

12. Kp 0 0 0 0 1 0 0 0 Sixth European Space Weather Week, 16-20 November 2009, Brugge

13. Statistic We found 200 events with h larger than 1.5 in 2004 and 32 events with h > 2.0, hierin 10 values of h larger than 2 occured in just one day (8th July 2004) 90 % days with h > 2.0 have Kp =< 4 132 events with h > 1.5 occured in days with Ap < 10 Sixth European Space Weather Week, 16-20 November 2009, Brugge

14. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

15. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

16. Sixth European Space Weather Week, 16-20 November 2009, Brugge

17. The high peaks (2-2.7) of the magnetic index correlate in time with large (+1.6 MHz and -1.1 MHz) punctual median deviations of foE. Such punctual deviations can suggest local inhomogeneities (vertical drifts) in the ionosphere. The correlation in space is not trivial. The strong peak of h is situated on the map between the positive and negative deviations of foE. Sixth European Space Weather Week, 16-20 November 2009, Brugge

18. Additional observation is connected with correlation in time of the high h value with the negative median deviations of h’F2 (in some cases up to -90 km) Sixth European Space Weather Week, 16-20 November 2009, Brugge

19. Pruhonice Juliusruh Sixth European Space Weather Week, 16-20 November 2009, Brugge

20. 100 % of thedayly very high h values correlate in time with foEs, but our statistic is in progress. Sixth European Space Weather Week, 16-20 November 2009, Brugge

21. We still don’t know why the largest values of h do not correlate with the largest values of foEs at the same time, we would like to know whether is a lag between maxima of h and foEs. Sixth European Space Weather Week, 16-20 November 2009, Brugge

22. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplication and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

23. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplication and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

24. The increase of h (external part of the magnetic field vertical component Z ) is accompanied with decreasing of the hight of the maximum electron concentration . Such punctual deviations can suggest local inhomogeneities (vertical drifts) in the ionosphere. Sixth European Space Weather Week, 16-20 November 2009, Brugge

25. The increase of the electromagnetic activity can cause lightnings in troposphere. The situational analysis to explain the geophysical aspect is in progress. Sixth European Space Weather Week, 16-20 November 2009, Brugge

26. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

27. The plan of the presentation • Presentation of indexh • Indexhduringveryquietdays (Kp = 0-1) • Correlation of hwithionosphericcharacteristics • Physics and interpretation of the results • Operationalapplications and conclusions Sixth European Space Weather Week, 16-20 November 2009, Brugge

28. Applicansions andConclusions The main advantages of h index are the simplicity of the method of separation of the external part of the magnetic field and possibility of using data from a single station for such separation. Application to prediction is under development. Usually measured magnetic indices used in ionospheric modeling represent the magnetic activity at the position of the magnetic observatories which could not represent the magnetic properties at the positions of the ionospheric observatories. The magnetic indices obtained by interpolation method at the positions of ionospheric observatories are presented. Sixth European Space Weather Week, 16-20 November 2009, Brugge

29. Conclusions The high peaks (2-2.7) of the new magnetic index correlate in time with large (+1.6 MHz and -1.1 MHz) punctual median deviations of foE. Such punctual deviations can suggest local inhomogeneities (vertical drifts) in the ionosphere. The correlation in space is not trivial. The strong peak of h is situated on the map between the positive and negative deviations of foE. Additional observation is connected with correlation in time of the high h value with the negative median deviations of h’F2 (in some cases up to -90 km). Sixth European Space Weather Week, 16-20 November 2009, Brugge

30. Conclusions The large (>1.5) values of h correlate in time with occurring of the sporadic E layer (in all cases there is enough data to produce maps of foEs), but the largest values of h do not correlate in time with the largest critical frequency foEs in the same place. The increase of the electromagnetic activity can cause lightnings in troposphere. . Sixth European Space Weather Week, 16-20 November 2009, Brugge