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Jacchia-Bowman 2008 Dst Density Model

Jacchia-Bowman 2008 Dst Density Model. Bruce R Bowman Elizabeth A Wolfe Space Analysis/A9A Air Force Space Command. DOD Distribution A Approved for public release Distribution unlimited. Introduction. JB2008 Dst storm model 2003 (Oct, Nov) and 2004 (Nov) Major Storms

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Jacchia-Bowman 2008 Dst Density Model

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  1. Jacchia-Bowman 2008 Dst Density Model Bruce R Bowman Elizabeth A Wolfe Space Analysis/A9A Air Force Space Command DOD Distribution A Approved for public release Distribution unlimited

  2. Introduction • JB2008 Dst storm model • 2003 (Oct, Nov) and 2004 (Nov) Major Storms • Pre-storm conditioning • Dst sub-dip variations • Extended density variations at storm max • Storm recovery relaxation parameters • Post storm base recovery

  3. JB2008 Geomagnetic Storm Modeling • All previous empirical models use ap geomagnetic index for storm modeling • The 3-hour ap is a measure of general magnetic activity over the Earth, and responds primarily to currents flowing in the ionosphere and only secondarily to magnetospheric variations • The ap index is determined by observatories at high latitudes which can be blind to energy input during large storms (Huang and Burke, 2004) • The Disturbance Storm Time (Dst) index is primarily used to indicate the strength of the storm-time ring current in the inner magnetosphere • During the main phase of magnetic storms, the ring current becomes highly energized and produces a southward-directed magnetic field perturbation at low latitudes on the Earth’s surface • The Dst index is determined from hourly measurements of the magnetic field made at four points around the Earth’s equator

  4. JB2008 Dst Equation Development • The thermosphere acts during storm periods as a driven-but-dissipative system whose dynamics can be represented by a differential equation • The driver is the magnetospheric electric field. Burke (2008) determined the relationship for the exospheric temperature responses as a function of Dst: •  parameters are empirically determined relaxation constants • The above equation must be integrated from storm beginning throughout the entire storm period in-order to compute ΔTc at every point during the storm • The above equation was optimized to fit the CHAMP and GRACE accelerometer density data, along with HASDM global densities. • Additional optimized equations based on different  values were developed for use during the Dst recovery phase period

  5. Single Event Major Geomagnetic Storm

  6. Typical Dst Storm Plot

  7. Multiple Density Peak Example

  8. GRACE Density Data

  9. 2004 Multiple CME Storm

  10. Dst Values During 2004 Storm

  11. 2004 Storm Model Density Ratios

  12. Dst Sub-Dip Example

  13. 2003 Multiple CME Storm Event

  14. JB2008 Model with Main Phase  Values

  15. JB2008 Model with Adjusted  Values

  16. Relaxation Parameters Main phase relaxation parameters: 1 = 6.5 hrs 2 = 7.7 hrs Recovery phase parameters: 1 =  hrs 2 = 1.0 hrs

  17. Dst Sub-Dip Example

  18. GRACE Density with Adjusted  Values

  19. Storm Recovery Example

  20. Density Ratios with CHAMP and GRACE

  21. Geomagnetic Storm Model Errors

  22. JB2008 Web Site

  23. Backup Slides

  24. All 2003 Solar Data

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