1. Analyzing the Large-Scale Curvature of Interplanetary Shocks Marissa Vogt Thesis Supervisor: Dr. Justin Kasper May 24, 2006

2. Objective Examine large-scale curvature of interplanetary shocks using data from two spacecraft, ACE and Wind Examine large-scale curvature of interplanetary shocks using data from two spacecraft, ACE and Wind

3. Background Sun releases the solar wind Sun releases the solar wind and CMEs and CMEs CMEs, solar wind interact CMEs, solar wind interact with our magnetosphere with our magnetosphere Shock waves generated when Shock waves generated when CMEs plow into the solar wind CMEs plow into the solar wind Solar wind data from Solar wind data from spacecraft can be used to study shocks spacecraft can be used to study shocks Shock parameters can be calculated directly or using multi-spacecraft timing methods Shock parameters can be calculated directly or using multi-spacecraft timing methods

4. Recent Work on Spatial Structure Timing methods assume that shock is planar, but data from multiple spacecraft do not provide a consistent solution [Szabo (2005), Teresawa et al. (2005)] Timing methods assume that shock is planar, but data from multiple spacecraft do not provide a consistent solution [Szabo (2005), Teresawa et al. (2005)] Neugebauer and Giacalone (2005) concluded shock surface is not planar, calculated R c Neugebauer and Giacalone (2005) concluded shock surface is not planar, calculated R c Numerical models by Manchester et. al predict 3-D structure Numerical models by Manchester et. al predict 3-D structure

5. Radius of Curvature (R c ) Measures the curvature of the shock surface Measures the curvature of the shock surface Found using shock normal and spacecraft location Found using shock normal and spacecraft location

6. Recent Work on Spatial Structure Timing methods assume that shock is planar, but data from multiple spacecraft do not provide a consistent solution [Szabo (2005), Teresawa et al. (2005)] Timing methods assume that shock is planar, but data from multiple spacecraft do not provide a consistent solution [Szabo (2005), Teresawa et al. (2005)] Neugebauer and Giacalone (2005) concluded shock surface is not planar, calculated R c Neugebauer and Giacalone (2005) concluded shock surface is not planar, calculated R c Numerical models by Manchester et. al predict 3-D structure Numerical models by Manchester et. al predict 3-D structure

7. Model of 3-D Structure by Manchester et al.

8. Objectives Examine R c parallel and perpendicular to the ecliptic plane – separately to look for 3-D structure Examine R c parallel and perpendicular to the ecliptic plane – separately to look for 3-D structure Look for small-scale structure (ripples), which may be a function of shock strength Look for small-scale structure (ripples), which may be a function of shock strength Assess the effects of small errors in calculating the shock normal Assess the effects of small errors in calculating the shock normal

9. Methods Calculate R c using data from shocks seen by both ACE and Wind spacecraft Calculate R c using data from shocks seen by both ACE and Wind spacecraft Data came from MIT’s Interplanetary Shock Database, with parameters calculated using MHD conservation equations Data came from MIT’s Interplanetary Shock Database, with parameters calculated using MHD conservation equations 99 shocks were analyzed 99 shocks were analyzed R c plotted as a function of: spacecraft separation, mach number, compression ratio R c plotted as a function of: spacecraft separation, mach number, compression ratio

10. R c in Ecliptic Plane

11. R c out of the Ecliptic

12. Large-Scale Curvature Conclusions Curvature can be seen by two spacecraft, provided that the separation distance is sufficiently large (> 50 R E ) Curvature can be seen by two spacecraft, provided that the separation distance is sufficiently large (> 50 R E ) 3-D structure: No evidence found, but spacecraft were too close together in the z direction 3-D structure: No evidence found, but spacecraft were too close together in the z direction Something is wrong at small separation distances Something is wrong at small separation distances

13. Errors in Calculating Shock Normal

14. Search for Surface Ripples Errors in shock normal could be due to calculations or small-scale curvature (i.e. ripples) Errors in shock normal could be due to calculations or small-scale curvature (i.e. ripples) Previous work suggested small-scale curvature which could be a function of shock strength Previous work suggested small-scale curvature which could be a function of shock strength Fast Mach Number and Compression Ratio are a measure of the shock strength Fast Mach Number and Compression Ratio are a measure of the shock strength Look for a correlation between R c and shock strength, especially at small separation distances Look for a correlation between R c and shock strength, especially at small separation distances Did not find evidence of surface ripples Did not find evidence of surface ripples

15. Conclusions Saw large-scale structure in ecliptic plane Saw large-scale structure in ecliptic plane Did not find evidence of 3-D structure Did not find evidence of 3-D structure Looked for evidence of small-scale structure of shock Looked for evidence of small-scale structure of shock Future work will hopefully show whether the behavior at small separation is caused by ripples or calculation errors Future work will hopefully show whether the behavior at small separation is caused by ripples or calculation errors

16. Acknowledgements Dr. Justin Kasper Dr. Justin Kasper Jane Connor Jane Connor EAPS Education Office EAPS Education Office