Analyzing the Large-Analyzing the Large-Scale Curvature of Scale Curvature of

Interplanetary ShocksInterplanetary Shocks

Marissa VogtMarissa Vogt

Thesis Supervisor: Dr. Justin Thesis Supervisor: Dr. Justin KasperKasper

May 24, 2006May 24, 2006

ObjectiveObjective

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

BackgroundBackground Sun releases the solar wind Sun releases the solar wind

and CMEsand CMEs CMEs, solar wind interact CMEs, solar wind interact

with our magnetospherewith our magnetosphere Shock waves generated when Shock waves generated when

CMEs plow into the solar windCMEs plow into the solar wind Solar wind data from Solar wind data from

spacecraft can be used to study shocksspacecraft can be used to study shocks Shock parameters can be calculated directly Shock parameters can be calculated directly

or using multi-spacecraft timing methodsor using multi-spacecraft timing methods

Recent Work on Spatial Recent Work on Spatial StructureStructure

Timing methods assume that shock is Timing methods assume that shock is planar, but data from multiple planar, but data from multiple spacecraft do not provide a consistent spacecraft do not provide a consistent solution [Szabo (2005), Teresawa et solution [Szabo (2005), Teresawa et al. (2005)]al. (2005)]

Neugebauer and Giacalone (2005) Neugebauer and Giacalone (2005) concluded shock surface is not planar, concluded shock surface is not planar, calculated Rcalculated Rcc

Numerical models by Manchester et. Numerical models by Manchester et. al predict 3-D structureal predict 3-D structure

Radius of Curvature (RRadius of Curvature (Rcc))

Measures the Measures the curvature of the curvature of the shock surfaceshock surface

Found using shock Found using shock normal and normal and spacecraft locationspacecraft location

Recent Work on Spatial Recent Work on Spatial StructureStructure

Timing methods assume that shock is Timing methods assume that shock is planar, but data from multiple planar, but data from multiple spacecraft do not provide a consistent spacecraft do not provide a consistent solution [Szabo (2005), Teresawa et solution [Szabo (2005), Teresawa et al. (2005)]al. (2005)]

Neugebauer and Giacalone (2005) Neugebauer and Giacalone (2005) concluded shock surface is not planar, concluded shock surface is not planar, calculated Rcalculated Rcc

Numerical models by Manchester et. Numerical models by Manchester et. al predict 3-D structureal predict 3-D structure

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

ObjectivesObjectives

Examine RExamine Rcc parallel and parallel and perpendicular to the ecliptic plane – perpendicular to the ecliptic plane – separately to look for 3-D structureseparately to look for 3-D structure

Look for small-scale structure Look for small-scale structure (ripples), which may be a function of (ripples), which may be a function of shock strengthshock strength

Assess the effects of small errors in Assess the effects of small errors in calculating the shock normalcalculating the shock normal

MethodsMethods

Calculate RCalculate Rc c using data from shocks using data from shocks seen by both ACE and Wind spacecraftseen by both ACE and Wind spacecraft

Data came from MIT’s Interplanetary Data came from MIT’s Interplanetary Shock Database, with parameters Shock Database, with parameters calculated using MHD conservation calculated using MHD conservation equationsequations

99 shocks were analyzed99 shocks were analyzed RRcc plotted as a function of: spacecraft plotted as a function of: spacecraft

separation, mach number, separation, mach number, compression ratiocompression ratio

RRcc in Ecliptic Plane in Ecliptic Plane

RRcc out of the Ecliptic out of the Ecliptic

Large-Scale Curvature Large-Scale Curvature ConclusionsConclusions

Curvature can be seen by two Curvature can be seen by two spacecraft, provided that the spacecraft, provided that the separation distance is sufficiently separation distance is sufficiently large (> 50 Rlarge (> 50 REE))

3-D structure: No evidence found, but 3-D structure: No evidence found, but spacecraft were too close together in spacecraft were too close together in the z directionthe z direction

Something is wrong at small Something is wrong at small separation distancesseparation distances

Errors in Calculating Shock Errors in Calculating Shock NormalNormal

Search for Surface RipplesSearch for Surface Ripples

Errors in shock normal could be due to Errors in shock normal could be due to calculations or small-scale curvature (i.e. calculations or small-scale curvature (i.e. ripples)ripples)

Previous work suggested small-scale curvature Previous work suggested small-scale curvature which could be a function of shock strengthwhich could be a function of shock strength

Fast Mach Number and Compression Ratio are Fast Mach Number and Compression Ratio are a measure of the shock strengtha measure of the shock strength

Look for a correlation between RLook for a correlation between Rcc and shock and shock strength, especially at small separation strength, especially at small separation distancesdistances

Did not find evidence of surface ripplesDid not find evidence of surface ripples

ConclusionsConclusions

Saw large-scale structure in ecliptic Saw large-scale structure in ecliptic planeplane

Did not find evidence of 3-D structureDid not find evidence of 3-D structure Looked for evidence of small-scale Looked for evidence of small-scale

structure of shockstructure of shock Future work will hopefully show Future work will hopefully show

whether the behavior at small whether the behavior at small separation is caused by ripples or separation is caused by ripples or calculation errorscalculation errors

AcknowledgementsAcknowledgements

Dr. Justin KasperDr. Justin Kasper Jane ConnorJane Connor EAPS Education OfficeEAPS Education Office