Solar Physics

, Volume 257, Issue 1, pp 99–112 | Cite as

Automated detection of EUV Polar Coronal Holes during Solar Cycle 23

  • M. S. Kirk
  • W. D. Pesnell
  • C. A. Young
  • S. A. Hess Webber
Open Access


A new method for automated detection of polar coronal holes is presented. This method, called perimeter tracing, uses a series of 171, 195, and 304 Å full disk images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO over solar cycle 23 to measure the perimeter of polar coronal holes as they appear on the limbs. Perimeter tracing minimizes line-of-sight obscurations caused by the emitting plasma of the various wavelengths by taking measurements at the solar limb. Perimeter tracing also allows for the polar rotation period to emerge organically from the data as 33 days. We have called this the Harvey rotation rate and count Harvey rotations starting 4 January 1900. From the measured perimeter, we are then able to fit a curve to the data and derive an area within the line of best fit. We observe the area of the northern polar hole area in 1996, at the beginning of solar cycle 23, to be about 4.2% of the total solar surface area and about 3.6% in 2007. The area of the southern polar hole is observed to be about 4.0% in 1996 and about 3.4% in 2007. Thus, both the north and south polar hole areas are no more than 15% smaller now than they were at the beginning of cycle 23. This compares to the polar magnetic field measured to be about 40% less now than it was a cycle ago.


Coronal holes Solar cycle, observations 


  1. Andretta, V., Jones, H.P.: 1997, Astrophys. J. 489, 375. CrossRefADSGoogle Scholar
  2. Benevolenskaya, E.E., Kosovichev, A.G., Scherrer, P.H.: 2001, Astrophys. J. 554, L107. CrossRefADSGoogle Scholar
  3. Bevington, P.R., Robinson, D.K.: 1992, Data Reduction and Error Analysis for the Physical Sciences, 2nd edn., McGraw-Hill, New York, 62. Google Scholar
  4. Beyer, W.H. (ed.): 1991, CRC Standard Mathematical Tables and Formulae, 29th edn., CRC Press, Boston, 175. zbMATHGoogle Scholar
  5. Bohlin, J.D.: 1977, In: Zirker, J.B. (ed.) Coronal Holes and High Speed Wind Streams, Colorado Associate University Press, Boulder, 27. Google Scholar
  6. de Toma, G., Arge, C.N.: 2005, In: Sankarasubramanian, K., Penn, M., Pevtsov, A. (eds.) Large-Scale Structures and Their Role in Solar Activity CS-346, Astron. Soc. Pac., San Francisco, 251. Google Scholar
  7. de Wit, T.D.: 2006, Solar Phys. 239, 519. CrossRefADSGoogle Scholar
  8. Harvey, K.L., Recely, F.: 2002, Solar Phys. 211, 31. CrossRefADSGoogle Scholar
  9. Henney, C.J., Harvey, J.W.: 2005, In: Sankarasubramanian, K., Penn, M., Pevtsov, A. (eds.) Large-Scale Structures and Their Role in Solar Activity CS-346, Astron. Soc. Pac., San Francisco, 261. Google Scholar
  10. Hoeksema, J.T.: 2008, The Wilcox Solar Observatory.
  11. Howard, R.F.: 2000, In: Cox, A.N. (ed.) Allen’s Astrophysical Quantities, 4th edn., Springer, New York, 362. Google Scholar
  12. Kahler, S.W., Hudson, H.S.: 2002, Astrophys. J. 574, 467. CrossRefADSGoogle Scholar
  13. Malanushenko, O.V., Jones, H.P.: 2005, Solar Phys. 226, 3. CrossRefADSGoogle Scholar
  14. Michielsen, K., Raedt, H.D.: 2001, Phys. Rep. 347, 461. zbMATHCrossRefADSMathSciNetGoogle Scholar
  15. Moses, D., Clette, F., Delaboudiniere, J.P., Artzner, G.E., Bougnet, M., Brunaud, J., et al.: 1997, Solar Phys. 175, 571. CrossRefADSGoogle Scholar
  16. Pesnell, W.D., Goldberg, R.A., Jackman, C.H., Chenette, D.L., Gaines, E.E.: 2000, J. Geophys. Res. 105, 22954. Google Scholar
  17. Press, W.H., Teukolsky, S.A., Vetterling, W.T., Flannery, B.P.: 1996, Numerical Recipes in Fortran 77: The Art of Scientific Computing, 2nd edn., Cambridge University Press, Cambridge, 650. zbMATHGoogle Scholar
  18. Schatten, K.H.: 2005, Geophys. Res. Lett. 32, 21106. CrossRefADSGoogle Scholar
  19. Schatten, K.H., Scherrer, P.H., Svalgaard, L., Wilcox, J.M.: 1978, Geophys. Res. Lett. 5, 411. CrossRefADSGoogle Scholar
  20. Sheeley, N.R., Wang, Y.M., Harvey, J.W.: 1989, Solar Phys. 119, 323. CrossRefADSGoogle Scholar
  21. Svalgaard, L., Cliver, E.W., Kamide, Y.: 2005, Geophys. Res. Lett. 32, 1104. CrossRefGoogle Scholar
  22. Waldmeier, M.: 1981, Solar Phys. 70, 251. CrossRefADSGoogle Scholar

Copyright information

© The Author(s) 2009

Authors and Affiliations

  • M. S. Kirk
    • 1
  • W. D. Pesnell
    • 2
  • C. A. Young
    • 1
  • S. A. Hess Webber
    • 3
  1. 1.ADNET Systems Inc.NASA Goddard Space Flight CenterGreenbeltUSA
  2. 2.NASA Goddard Space Flight CenterGreenbeltUSA
  3. 3.Catholic University of AmericaWashington D.C.USA

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