far-side imaging and activity irene gonzález hernández and the gong and mdi far-side teams...
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Far-side Imaging and ActivityFar-side Imaging and Activity
Irene González Hernández and the GONG and MDI far-Irene González Hernández and the GONG and MDI far-side teamsside teams
National Solar Observatory, Tucson, AZNational Solar Observatory, Tucson, AZStanford University, Stanford, CAStanford University, Stanford, CA
Northwest Research Associates (CORA), Boulder, CONorthwest Research Associates (CORA), Boulder, CO
ContentsContents Introduction to far-side seismic holography
Improving the far-side maps
Calibrating the seismic signal
Success Rate
Variation of the mean phase with the solar cycle !
Improving the signal to noise
Future work and conclusions
Helioseismic Imaging of the Helioseismic Imaging of the FarsideFarside
Helioseismic imaging of sunspots at their antipodes. Lindsey, C. Helioseismic imaging of sunspots at their antipodes. Lindsey, C. & Braun, D.C, 1990, SoPh.& Braun, D.C, 1990, SoPh.
Seismic Images of the Far Side and Interior of the Sun Lindsey, Seismic Images of the Far Side and Interior of the Sun Lindsey, C. & Braun, D.C, 2000, Science.C. & Braun, D.C, 2000, Science.
Pupil
Helioseismic Imaging of the Helioseismic Imaging of the FarsideFarside
Phase of the Correlation
),,(),,(),,( tzHtzHdtzC rrr
Improving the far-side monitorImproving the far-side monitor
FS00543
85 %
MDI (HMI)
GONG
Time Distance ( HMI + GONG)
Users able to subscribe to alerts > %
|B|
Calibrating the far-side signalCalibrating the far-side signal
Carrington Longitude
sin
(lati
tud
e)
Active Region NOAA-10808
Aug 29 -> Sep 9 2005AR108
08
Active Region NOAA-10923
Oct 31 -> Nov 10 2006
AR10923
sin
(lati
tud
e)
Calibrating the far-side signalCalibrating the far-side signal
Calibrating the far-side signalCalibrating the far-side signal
““far-side” imaging of the near far-side” imaging of the near sideside
1 x 3 skip method actually extends well onto the near side!
Success rateSuccess rate
MDI
MDI
+
GONG
GONG
Success RateSuccess Rate
Why the improvement?Why the improvement?
Different length Different length of time seriesof time series
Duty CycleDuty Cycle Phase correctionPhase correction Bad dataBad data
Why the improvement?Why the improvement? Phase CorrectionPhase Correction
Why the improvement?Why the improvement? Mean Phase --> Temporal VariationMean Phase --> Temporal Variation
Variation of the seismic solar Variation of the seismic solar radiusradius Solar acoustic radius variation --> solar cycle variationSolar acoustic radius variation --> solar cycle variation
Kholikov & Hill,
2008, SoPh
Solar cycle variationSolar cycle variation Mean Phase --> Solar Cycle variation --> Solar acoustic Mean Phase --> Solar Cycle variation --> Solar acoustic
radius variation (??)radius variation (??)
Solar cycle variationSolar cycle variation Mean Phase --> Solar Cycle variation --> Solar acoustic Mean Phase --> Solar Cycle variation --> Solar acoustic
radius variation--> Localized to surface magnetic areas (?)radius variation--> Localized to surface magnetic areas (?)
Far-side maps from time-Far-side maps from time-distacedistace
GONG
MDI
September 03 2005
Courtesy of Junwei Zhao
Seismic holographyTime distance
NOAA 10808
ArtifactsArtifacts Thomas Hartlep,Junwei Zhao Nagi N. Mansour, and Alexander G. Thomas Hartlep,Junwei Zhao Nagi N. Mansour, and Alexander G.
Kosovichev Kosovichev Validating Time-Distance Far-Side Imaging of Solar Validating Time-Distance Far-Side Imaging of Solar Active Regions through Numerical Simulations Active Regions through Numerical Simulations
ApJ, 689:1373–1378, 2008 December 20ApJ, 689:1373–1378, 2008 December 20
Why the improvement?Why the improvement?GONG MDI
060902
060903
060902
060903
Can we improve the Green’s Functions?
More realistic model --> Collaboration with Fernando Pérez at the IAC
Empirical calibration of the dispersion
Dispersion for several bounces
Conclusions and Future workConclusions and Future work
MDI GONG
FS00543
85 %
Time Distance ( HMI + GONG)
Users able to subscribe to alerts > %
|B|
Improving the Maps
Calibration --> extending to the front side
Success Rate --> more accurate determination
Better Signal to Noise --> HMI data/ combination of ray paths / green’s functions / artifacts
Understanding Solar Cycle variations !!!
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