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SHINE August, 2006 C.J. Henney (NSO/SOLIS) SOLIS/VSM Coronal Hole Estimation Maps Carl J. Henney (NSO/SOLIS)
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) KPVT Coronal Hole Maps Daily “hand drawn” Coronal Hole images by K. Harvey and F. Recely span: 1992 to 2003 Daily “hand drawn” Coronal Hole images by K. Harvey and F. Recely span: 1992 to 2003 In addition, coronal hole synoptic maps by K. Harvey and F. Recely span: 1987 to 2002 (see Harvey and Recely 2002). In addition, coronal hole synoptic maps by K. Harvey and F. Recely span: 1987 to 2002 (see Harvey and Recely 2002). Non-scanned hand drawn daily and synoptic maps back to 1974. Non-scanned hand drawn daily and synoptic maps back to 1974. The “hand drawn” maps stopped with the beginning of SOLIS in September 2003. The “hand drawn” maps stopped with the beginning of SOLIS in September 2003.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) VSM Automated CH Maps SOLIS-VSM began He I 1083 nm measurements in August 2003. SOLIS-VSM began He I 1083 nm measurements in August 2003. Daily He I 1083 nm images are publicly available (fits files will be available in fall 2006), along with automated coronal hole images and synoptic maps at: http://solis.nso.edu Daily He I 1083 nm images are publicly available (fits files will be available in fall 2006), along with automated coronal hole images and synoptic maps at: http://solis.nso.edu
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Following Henney & Harvey (2005): Start with an average 1083 nm and an average magnetogram created with two consecutive observations respectively in heliographic coordinates (sine-latitude and longitude). The following images are from July 14, 2003. Start with an average 1083 nm and an average magnetogram created with two consecutive observations respectively in heliographic coordinates (sine-latitude and longitude). The following images are from July 14, 2003.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 2: spatially smooth Step 2: spatially smooth
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 2: spatially smooth Step 2: spatially smooth Step 3: set all values above zero to a fixed value. Step 3: set all values above zero to a fixed value.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 1: trim the East-West limb data and retain only values above 1/10 the median of positive values. Step 2: spatially smooth Step 2: spatially smooth Step 3: set all values above zero to a fixed value. Step 3: set all values above zero to a fixed value. Step 4: smooth with the morphological image analysis function Close ( e.g. Michielsen and Raedt, 2001 ) Step 4: smooth with the morphological image analysis function Close ( e.g. Michielsen and Raedt, 2001 )
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 5: remove regions that are too small to be a coronal hole. Step 5: remove regions that are too small to be a coronal hole. Step 6: use the indexes of non-zero spatial points to fill the smoothed image in step 2 with a large value (e.g. 10 4 ). Step 6: use the indexes of non-zero spatial points to fill the smoothed image in step 2 with a large value (e.g. 10 4 ).
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 5: remove regions that are too small to be a coronal hole. Step 5: remove regions that are too small to be a coronal hole. Step 6: use the indexes of non-zero spatial points to fill the smoothed image in step 2 with a large value (e.g. 10 4 ). Step 6: use the indexes of non-zero spatial points to fill the smoothed image in step 2 with a large value (e.g. 10 4 ).
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 5: remove regions that are too small to be a coronal hole. Step 5: remove regions that are too small to be a coronal hole. Step 6: use the indexes of non-zero spatial points to fill the smoothed image in step 2 with a large value (e.g. 10 4 ). Step 6: use the indexes of non-zero spatial points to fill the smoothed image in step 2 with a large value (e.g. 10 4 ). Step 7: smooth with the morphological image analysis function Open. Step 7: smooth with the morphological image analysis function Open.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Mean Percent Unipolarity The cut-off levels for the percent unipolarity relative to latitude were determined using the “hand drawn” maps for the period 1992 to 2003. The cut-off levels for the percent unipolarity relative to latitude were determined using the “hand drawn” maps for the period 1992 to 2003. The area of every coronal hole was projected into the corresponding daily average magnetic image (in heliographic coordinates). The area of every coronal hole was projected into the corresponding daily average magnetic image (in heliographic coordinates). 2,781 image pairs, with 11,241 coronal holes, were used in total. Figures from Henney & Harvey (2005)
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Recipe Step 8: remove regions that are too small to be a coronal hole. Step 8: remove regions that are too small to be a coronal hole. Step 9: remove regions that have a low percentage of unipolarity. Step 9: remove regions that have a low percentage of unipolarity. Step 10: number the coronal holes and apply sign of polarity. Step 10: number the coronal holes and apply sign of polarity.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Comparison The auto-detection coronal hole map projected into heliocentric coordinates of the hand-drawn.
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Comparison from Malanushenko & Jones (2004) An example when the two maps differed: from Henney & Harvey (2005)
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Coronal Hole Detection Comparison from Malanushenko & Jones (2004) from Henney & Harvey (2005)
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Solar Wind Forecasting The estimated area and location of coronal hole regions can be used to forecast solar wind velocities (up to 8.5 days in advance) using a simple empirical model with only a single full-disk observation (Robbins, Henney, and Harvey 2005). The estimated area and location of coronal hole regions can be used to forecast solar wind velocities (up to 8.5 days in advance) using a simple empirical model with only a single full-disk observation (Robbins, Henney, and Harvey 2005). From Robbins, Henney, and Harvey (2005)
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SHINE August, 2006 C.J. Henney (NSO/SOLIS) Acknowledgements The coronal hole data used here was compiled by K. Harvey and F. Recely using NSO KPVT observations under a grant from the NSF. The coronal hole data used here was compiled by K. Harvey and F. Recely using NSO KPVT observations under a grant from the NSF. SOLIS VSM data used here are produced cooperatively by NSF/NSO and NASA/GSFC. SOLIS VSM data used here are produced cooperatively by NSF/NSO and NASA/GSFC. Part of this research was supported in part by the Office of Naval Research Grant N00014-91-J-1040. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation. Part of this research was supported in part by the Office of Naval Research Grant N00014-91-J-1040. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation. References Henney, C.J., & Harvey, J.W. 2005, ASP conf. Series, Vol. 346, 261. Malanushenko, O.V., & Jones, H.P. 2004, Solar Physics, Vol. 222, 43. Robbins, S., Henney, C.J., & Harvey, J.W. 2006, Solar Physics, Vol. 233, 265.
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