1. Tidal Structures in the Equatorial Ionosphere C. Y. Huang 1, S. H. Delay 2, E. K. Sutton 1, and P. A. Roddy 1, 1 Air Force Research Laboratory 2 Boston College MURI Workshop 28 October 2010

2. Outline Broad Plasma Decreases (BPDs) in C/NOFS PLP – description Detrending C/NOFS PLP plasma densities - procedure Statistical analysis of detrended plasma densities for June 2008 GRACE neutral density residuals for June 2008 2

3. Communication/Navigation Outage Forecast System Launched May 2008 into low-inclination orbit Goal is forecasting of scintillation 5 experiments –Planar Langmuir Probe –Vector Electric Field Investigation –Ion Velocity Monitor / Neutral Wind Monitor –RF Beacon –GPS

4. 4 Simultaneous Broad Plasma Decreases C/NOFS and DMSP 22 – 23 UT, 19 June 2008 C/NOFS BPD: Altitude 400 – 450 km, width 5 hrs LT DMSP BPD: Altitude 840 km, width 30  latitude [Huang et al., 2009, GRL]

5. Detrend C/NOFS Plasma Densities Variations in plasma density obscured by changing orbital altitude Detrend PLP densities using IRI (ver. 2007.3) as follows: N det = N(PLP) * (IRI(500)/IRI(C/NOFS)) N(PLP) is the density measured by PLP along the orbit; IRI (500) is the model value at 500 km, at the equator, at C/NOFS longitude, UT, DOY etc.; IRI (C/NOFS) is the model value at C/NOFS location, UT, DOY etc. Use 1-minute averages of PLP densities Result - densities all mapped to 500 km altitude, equator Plots show density as function of geographic longitude 5

6. 6 C/NOFS Orbit 953, 19 June 2008

7. 7 Initial and Detrended C/NOFS Densities Orbit 953, 19 June 2008

8. Dayside Detrended Plasma Densities June 2008 8  IRI  PLP

9. Nightside Detrended Plasma Densities June 2008 9  IRI  PLP

10. Ionospheric Tidal Structures PLP data analyzed from May 2008 to December 2009 Climatology of tidal structures similar to planetary wave climatology (strongest in June – August, weakest around December – January) Other C/NOFS experiments show similar wave-4 structures (electric fields, ion drifts,  n/n)

11. 11 June 2008 Plasma and Neutral Densities 20-22 LT Sector

12. 12 June 2008 Plasma and Neutral Densities 10-12 LT Sector

13. Summary Detrended PLP densities show tidal structures, most obvious on dayside Deep minimum persists on nightside around 330  (SAA) Climatology of plasma tides agrees with planetary wave source GRACE averaged neutral densities also show tidal structures Ion/neutral tides do not coincide! 13