Analyzing the Large-Scale Curvature of Interplanetary Shocks Marissa Vogt Thesis Supervisor: Dr....
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Transcript of Analyzing the Large-Scale Curvature of Interplanetary Shocks Marissa Vogt Thesis Supervisor: Dr....
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