1. 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) (1) National Solar Observatory, Tucson, AZ (2) NorthWest Research Associates, Boulder, CO (3) Stanford University, Stanford, CA

2. Contents Seismic imaging or Helioseismic holography Seismic imaging or Helioseismic holography Data: GONG near-real-time velocity images Data: GONG near-real-time velocity images Prediction capability: NOAA-10808 Prediction capability: NOAA-10808 Calibration of farside seismic holography signal Calibration of farside seismic holography signal Collaborations Collaborations Conclusions and future work Conclusions and future work

3. Helioseismic Imaging of the Farside Helioseismic imaging of sunspots at their antipodes. Lindsey, C. & Braun, D.C, 1990, SoPh. Helioseismic imaging of sunspots at their antipodes. Lindsey, C. & Braun, D.C, 1990, SoPh. Seismic Images of the Far Side and Interior of the Sun Lindsey, C. & Braun, D.C, 2000, Science. Seismic Images of the Far Side and Interior of the Sun Lindsey, C. & Braun, D.C, 2000, Science. Egression/Ingression Pupil

4. Helioseismic Imaging of the Farside Phase of the Correlation 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

5. GONG farside map (Sep 02 2005) Helioseismic Imaging of the Farside Longitude-Sin(lat) projection

6. GONG near-real-time data Continuous stream of velocity images Continuous stream of velocity images Quick calibration done at the sites Quick calibration done at the sites 215x215 Gaussian-smoothed velocity images 215x215 Gaussian-smoothed velocity images Transfer daily from six GONG stations Transfer daily from six GONG stations Images merged in Tucson Images merged in Tucson http://gong.nso.edu/quickreduce/quickpulse.html Farside maps calculated from 1440-min data series twice daily. Farside maps calculated from 1440-min data series twice daily. Maps calculated approx. 12 hours after the last image has been taken. Maps calculated approx. 12 hours after the last image has been taken. Recalculated if the duty-cycle increases due to extra transfer. Recalculated if the duty-cycle increases due to extra transfer. Full-hemisphere farside maps. Full-hemisphere farside maps. http://soi.stanford.edu/farside http://gong.nso.edu/data/farside

7. Prediction capability Carrington Longitude sin(latitude) Active Region NOAA-10808 Aug 29  Sep 9 2005 (GONG) Sept 7 2005 AR10808 Source: MLSO K-coronameter

8. Magnetic calibration Analysis of particular cases. Analysis of particular cases. Location Location Classification Classification Evolution of magnetic regions/sunspots Evolution of magnetic regions/sunspots Frontside holography  Relate phase-shifts calculated by seismic imaging with magnetic index on the visible sun. Frontside holography  Relate phase-shifts calculated by seismic imaging with magnetic index on the visible sun. Statistics, statistics: Statistics, statistics: GONG++ July 2001  present GONG++ July 2001  present Use Artificial data to calibrate the effect on the farside signal of different anomalies Use Artificial data to calibrate the effect on the farside signal of different anomalies Φ  B

9. Calibrating the farside signal

10. Source: www.solarmonitor.org Area(max)NSpots(max)Hale/McIntoshLocation FS region NOAA10484175069 βγδ / Ekc βγδ / EkcN04W29FS5700 NOAA104862200108 βγδ / Fkc βγδ / FkcS17W63FS5701 NOAA1048728023 β / Dao β / DaoN12W22 NOAA10488175061 βγδ / Fkc βγδ / FkcN08W69FS5702 NOAA1049522016 β / Dso β / DsoS22W48 NOAA1050141026 βγδ / Dki βγδ / DkiN03W32FS5703 NOAA10515809 β / Dso β / DsoS02W01 NOAA1051735019 β / Dao β / DaoS08W20

11. Calibrating the farside signal Source: www.solarmonitor.org Area(max)NSpots(max)Hale/McIntoshLocation FS region NOAA10484175069 βγδ / Ekc βγδ / EkcN04W29FS5700 NOAA104862200108 βγδ / Fkc βγδ / FkcS17W63FS5701 NOAA1048728023 β / Dao β / DaoN12W22 NOAA10488175061 βγδ / Fkc βγδ / FkcN08W69FS5702 NOAA1049522016 β / Dso β / DsoS22W48 NOAA1050141026 βγδ / Dki βγδ / DkiN03W32FS5703 NOAA10515809 β / Dso β / DsoS02W01 NOAA1051735019 β / Dao β / DaoS08W20

12. Magnetic calibration Phase differences calculated for the farside maps using 2.5 years of GONG++ data versus latitude (from August 2001 to December 2003, left). The crosses represent the value of each pixel versus the latitude position in the map. On the right panel, the magnetic flux of the synoptic maps (Kitt Peak) from the same period. Both panels show a greater concentration of magnetic activity in the southern hemisphere as well as major peaks surrounding the 15° latitudes. It is also noticeable that strong features appear closer to the Equator, possibly corresponding to activity at the latest phase of the solar cycle.

13. Magnetic calibration 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.

14. Magnetic calibration Evolution of the number of FS Active region from July 2001 to August 2005

15. Magnetic 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)

16. Magnetic Calibration Artificial data with simulated “sunspot” Angular size: 25 –40 degrees Angular size: 25 –40 degrees Radial extend: 1Mm Radial extend: 1Mm Sound speed perturbation: Increase ~10% on average. Sound speed perturbation: Increase ~10% on average.

17. 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

18. Conclusions and future work MDI and GONG pipelines are providing daily full-hemisphere farside maps. MDI and GONG pipelines are providing daily full-hemisphere farside maps. Large active regions are seen in consecutive farside maps. Large active regions are seen in consecutive farside maps. Scientific Calibration Scientific Calibration Empirical calibration: Statistics with farside results +frontside analysis Empirical calibration: Statistics with farside results +frontside analysis Calibration of artificial “sunspots” Calibration of artificial “sunspots” Calibrate effect of several bounces and dispersion relation Calibrate effect of several bounces and dispersion relation Ghost signature (?) Ghost signature (?) Collaboration with irradiance variation studies Collaboration with irradiance variation studies Continue refining the technique to improve its capability as a space weather prediction tool Continue refining the technique to improve its capability as a space weather prediction tool