Farside Helioseismic Farside Helioseismic Holography: Recent Holography: Recent Advances Advances I. González Hernández (1), D. Braun (2), S. M. Hanasoge(3), F. Hill (1), C. Lindsey (2), P. Scherrer (3) (1) National Solar Observatory, Tucson, AZ (2) NorthWest Research Associates, Boulder, CO (3) Stanford University, Stanford, CA
15
Embed
Farside Helioseismic Holography: Recent Advances I. González Hernández (1), D. Braun (2), S. M. Hanasoge(3), F. Hill (1), C. Lindsey (2), P. Scherrer (3)
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
I. González Hernández (1), D. Braun (2), S. M. Hanasoge(3), F. Hill (1),
C. Lindsey (2), P. Scherrer (3)
(1) National Solar Observatory, Tucson, AZ
(2) NorthWest Research Associates, Boulder, CO
(3) Stanford University, Stanford, CA
ContentsContents
Seismic imaging or Helioseismic Seismic imaging or Helioseismic holographyholography
Data: GONG near-real-time velocity imagesData: GONG near-real-time velocity images Prediction capability: NOAA-10808Prediction capability: NOAA-10808 Calibration of farside seismic holography Calibration of farside seismic holography
signalsignal CollaborationsCollaborations Conclusions and future workConclusions and future work
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, C. Seismic Images of the Far Side and Interior of the Sun Lindsey, C. & Braun, D.C, 2000, Science.& Braun, D.C, 2000, Science.
PtttzGdtdtzH ),(),,,,(),,( 2 rrrrr
Egression/Ingression
Pupil
Helioseismic Imaging of the Helioseismic Imaging of the FarsideFarside
Phase of the
Correlation
),,(),,(),,( tzHtzHdtzC rrr
Phase-difference due to:
Reduction of gas pressure in magnetic region displacement of density variation “Acoustic Wilson depression”
Sound speed enhancement (evidence from acoustic moats) due to thermal anomalies
Inclination of the magnetic field
GONG near-real-time dataGONG near-real-time data Continuous stream of velocity imagesContinuous stream of velocity images Quick calibration done at the sitesQuick calibration done at the sites 215x215 Gaussian-smoothed velocity images215x215 Gaussian-smoothed velocity images Transfer daily from six GONG stationsTransfer daily from six GONG stations Images merged in TucsonImages merged in Tucsonhttp://gong.nso.edu/quickreduce/quickpulse.html
Farside maps calculated from 1440-Farside maps calculated from 1440-min data series twice daily.min data series twice daily.Maps calculated approx. 12 hours Maps calculated approx. 12 hours after the last image has been taken.after the last image has been taken.Recalculated if the duty-cycle Recalculated if the duty-cycle increases due to extra transfer.increases due to extra transfer. Full-hemisphere farside maps.Full-hemisphere farside maps.http://soi.stanford.edu/farsidehttp://gong.nso.edu/data/farside
Prediction capabilityPrediction capability
Carrington Longitude
sin
(lati
tud
e)
Active Region NOAA-10808
Aug 29 Sep 9 2005 (GONG)
Sept 7 2005
AR10808
Source: MLSO K-coronameter
Magnetic calibrationMagnetic calibration
Analysis of particular cases.Analysis of particular cases. LocationLocation ClassificationClassification Evolution of magnetic regions/sunspotsEvolution of magnetic regions/sunspots
Frontside holography Frontside holography Relate phase-shifts Relate phase-shifts calculated by seismic imaging with calculated by seismic imaging with magnetic index on the visible sun.magnetic index on the visible sun.
Statistics, statistics:Statistics, statistics: GONG++ July 2001 GONG++ July 2001 present present
Use Artificial data to calibrate the effect on Use Artificial data to calibrate the effect on the farside signal of different anomaliesthe farside signal of different anomalies
Φ B
Calibrating the farside signalCalibrating the farside signal
Calibrating the farside signalCalibrating the farside signal
Histograms of phase difference (from farside maps, left) and magnetic index (Kitt Peak magnetograms, right) versus latitude. The data used span from July 2001 to August 2003. The histograms in both cases seem to agree on the presence of more magnetic activity in the southern hemisphere for this period of time.
Magnetic CalibrationMagnetic Calibration
Scatter plots of phase-shifts from the synoptic maps constructed from farside calculated images (Carrington Rotation 1996, left, and 2009, right) versus the square of the magnetic flux of the frontside synoptic maps from magnetograms (Kitt Peak)
Magnetic CalibrationMagnetic Calibration
Artificial data with simulated “sunspot”Artificial data with simulated “sunspot” Angular size: 25 –40 degreesAngular size: 25 –40 degrees Radial extend: 1MmRadial extend: 1Mm Sound speed perturbation: Increase ~10% on average.Sound speed perturbation: Increase ~10% on average.
• Bright green plage
• (?) faculae
• Dark red penumbra
• Bright red umbra
• Background blue quiet
• Light Blue faint
• Black network
• Dark green active network
Irradiance Variation
Courtesy of Juan Fontenla
Conclusions and future workConclusions and future work
MDI and GONG pipelines are providing daily full-MDI and GONG pipelines are providing daily full-hemisphere farside maps.hemisphere farside maps.
Large active regions are seen in consecutive Large active regions are seen in consecutive farside maps.farside maps.
Scientific Calibration Scientific Calibration Empirical calibration: Statistics with farside results Empirical calibration: Statistics with farside results
+frontside analysis+frontside analysis Calibration of artificial “sunspots”Calibration of artificial “sunspots” Calibrate effect of several bounces and dispersion Calibrate effect of several bounces and dispersion
Collaboration with irradiance variation studiesCollaboration with irradiance variation studies Continue refining the technique to improve its Continue refining the technique to improve its
capability as a space weather prediction toolcapability as a space weather prediction tool