1. The day-to-day longitudinal variability of the global ionospheric density distribution: Preliminary results E.E. Pacheco and E. Yizengaw Institute for Scientific Research, Boston College, Boston, USA LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 2011

2. Outline Introduction Instruments and methodology Observations Conclusions 1LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 2011

3. Introduction Ionospheric density is a important parameter The low latitude ionospherIc density changes can affect communication and navigation signals Electrodynamics that controls the ionospheric density distribution is not yet fully understood Wind driven electric field systems modify the density structure of the ionosphere. LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 20112

4. INSTRUMENTS GPS RECEIVERS NETWORK Madrigal CHAMP – topside TEC Alt ~ 340 km, orbit~98 degree, period~100min TIMED-TIDI- Zonal wind in the E region Alt~600 km LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 20113

5. METHODOLOGY Geomagnetic quiet time conditions, 2008. Global TEC map as a function of longitude and latitude at fix local times (bins: 10  longitude by 2  latitude) Day-to-day variability of TEC which includes the wavenumber four structures during day and nightside TIDI’s global zonal wind maps ~ 60 days average LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 20114

6. Motivation What causes the longitudinal density variability, including the formation of wavenumber-4, during geomagnetic quiet period? Does zonal or meridional wind play a vital role for the formation of wavenumber-4 structure? LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 20115

7. Dayside LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 20116

8. 7

9. 8

10. Dayside LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 20119

11. 10

12. LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 201111

13. LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 201112

14. Nightside LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 201113

15. LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 201114 ZONAL WIND FROM TIDI INSTRUMENT

16. LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 201115 MERIDIONAL WIND FROM TIDI INSTRUMENT

17. C/NOFS and ROCSAT-1 ION DRIFTS LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 201116

18. Conclusions 17LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 2011 The ionospheric density is longitudinal dependent Wavenumber-4 is detected on the TEC measurements Wavenumber-4 structure can extend to post- midnight hours It seems the zonal wind has more impact on the formation of wavenumber-4 structure than the meridional wind, but more studies are needed to understand the electrodynamics that controls the longitudinal variability.

19. LISN WORKSHOP, São José dos Campos, SP, Brazil, Nov 7-10, 2011 18 Thank you