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Resolving the 180° Ambiguity in Solar Vector Magnetic Field Data: Evaluating the Effects of Noise, Spatial Resolution, and Method Assumptions

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The objective testing of algorithms for performing ambiguity resolution in vector magnetic field data is continued, with an examination of the effects of noise in the data. Through the use of analytic magnetic field models, two types of noise are “added” prior to resolving: noise to simulate Poisson photon noise in the observed polarization spectra, and a spatial binning to simulate the effects of unresolved structure. The results are compared through the use of quantitative metrics and performance maps. We find that while no algorithm severely propagates the effects of Poisson noise beyond very local influences, some algorithms are more robust against high photon-noise levels than others. In the case of limited spatial resolution, loss of information regarding fine-scale structure can easily result in erroneous solutions. Our tests imply that photon noise and limited spatial resolution can act so as to make assumptions used in some ambiguity resolution algorithms no longer consistent with the observed magnetogram. We confirm a finding of the earlier comparison study that results can be very sensitive to the details of the treatment of the observed boundary and the assumptions governing that treatment. We discuss the implications of these findings, given the relative sensitivities of the algorithms to the two sources of noise tested here. We also touch on further implications for interpreting observational vector magnetic field data for general solar physics research.

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  • Auer, L.H., Heasley, J.N., House, L.L.: 1977, Solar Phys. 55, 47.

    Article  ADS  Google Scholar 

  • Borrero, J.M., Solanki, S.K.: 2008, Astrophys. J. 687, 668.

    Article  ADS  Google Scholar 

  • Canfield, R.C., de La Beaujardière, J.F., Fan, Y., Leka, K.D., McClymont, A.N., Metcalf, T., Mickey, D.L., Wülser, J.P., Lites, B.W.: 1993, Astrophys. J. 411, 362.

    Article  ADS  Google Scholar 

  • Crouch A.D., Barnes G., Leka K.D.: 2009, Solar Phys., submitted.

  • Georgoulis, M.K.: 2005, Astrophys. J. 629, L69.

    Article  ADS  Google Scholar 

  • Ichimoto, K., Lites, B., Elmore, D., Suematsu, Y., Tsuneta, S., Katsukawa, Y., et al.: 2008, Solar Phys. 249, 233.

    Article  ADS  Google Scholar 

  • Keller, C.U., The Solis Team: 2001, In: Sigwarth, M. (ed.) Advanced Solar Polarimetry – Theory, Observation, and Instrumentation, ASP Conf. Ser. 236, 16.

  • Labonte, B.: 2004, Solar Phys. 221, 191.

    Article  ADS  Google Scholar 

  • Labonte, B., Mickey, D.L., Leka, K.D.: 1999, Solar Phys. 189, 1.

    Article  ADS  Google Scholar 

  • Leka, K.D., Barnes, G., Crouch, A.D.: 2009, In: Second Hinode Science Meeting, ASP Conf. Ser., in press.

  • Lites, B.W., Elmore, D.F., Streander, K.V., Sankarasubramanian, K., Rimmele, T.R., Sigwarth, M.: 2003, In: Trujillo-Bueno, J., Sanchez Almeida, J. (eds.) Solar Polarization 3, ASP Conf. Ser. 307, 324.

  • Metcalf, T.R.: 1994, Solar Phys. 155, 235.

    Article  ADS  Google Scholar 

  • Metcalf, T.R., Leka, K.D., Barnes, G., Lites, B.W., Georgoulis, M.K., Pevtsov, A.A., et al.: 2006, Solar Phys. 237, 267.

    Article  ADS  Google Scholar 

  • Mickey, D.L., Canfield, R.C., LaBonte, B.J., Leka, K.D., Waterson, M.F., Weber, H.M.: 1996, Solar Phys. 168, 229.

    Article  ADS  Google Scholar 

  • Parker, E.N.: 1996, Astrophys. J. 471, 485.

    Article  ADS  Google Scholar 

  • Sakurai, T., Ichimoto, K., Shinoda, Y., Noguchi, M., Hiei, E., Li, T., et al.: 1995, Publ. Astron. Soc. Japan 47, 81.

    ADS  Google Scholar 

  • Sankarasubramanian, K., Lites, B., Gullixson, C., Elmore, D., Hegwer, S., Streander, K., Rimmele, T., Fletcher, S., Gregory, S., Sigwarth, M.: 2006, In: Casini, R., Lites, B.W. (eds.) Solar Polarization 4, ASP Conf. Ser. 358, 201.

  • Scherrer, P.H., Hoeksema, J.T., The HMI Team: 2006, 36th COSPAR Scientific Assembly, Abstract No. 1469 (in CDROM).

  • Skumanich, A., Lites, B.W.: 1987, Astrophys. J. 322, 473.

    Article  ADS  Google Scholar 

  • Stenflo, J.O., Keller, C.U.: 1997, Astron. Astrophys. 321, 927.

    ADS  Google Scholar 

  • Titov, V.S., Priest, E.R., Demoulin, P.: 1993, Astron. Astrophys. 276, 564.

    ADS  Google Scholar 

  • Tsuneta, S., Ichimoto, K., Katsukawa, Y., Nagata, S., Otsubo, M., Shimizu, T., et al.: 2008, Solar Phys. 249, 167.

    Article  ADS  Google Scholar 

  • Venkatakrishnan, P., Gary, G.A.: 1989, Solar Phys. 120, 235.

    Article  ADS  Google Scholar 

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Correspondence to K. D. Leka.

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T.R. Metcalf deceased, July 2007.

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Leka, K.D., Barnes, G., Crouch, A.D. et al. Resolving the 180° Ambiguity in Solar Vector Magnetic Field Data: Evaluating the Effects of Noise, Spatial Resolution, and Method Assumptions. Sol Phys 260, 83–108 (2009).

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