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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. Outline. Broad Plasma Decreases (BPDs) in C/NOFS PLP – description
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Tidal Structures in the Equatorial Ionosphere C. Y. Huang1, S. H. Delay2, E. K. Sutton1, and P. A. Roddy1, 1Air Force Research Laboratory 2Boston College MURI Workshop 28 October 2010
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
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
Simultaneous Broad Plasma Decreases C/NOFS and DMSP22 – 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]
Detrend C/NOFS Plasma Densities • Variations in plasma density obscured by changing orbital altitude • Detrend PLP densities using IRI (ver. 2007.3) as follows: Ndet = 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
Initial and Detrended C/NOFS Densities Orbit 953, 19 June 2008
Dayside Detrended Plasma Densities June 2008 IRI PLP
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)
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!