1 / 16

Azimuth ambiguity resolution from dBz/dz

Azimuth ambiguity resolution from dBz/dz. M. Kubo (ISAS/JAXA), K. Shimada (University of Tokyo), K. Ichimoto, S. Tsuneta (NAOJ) and SOT-team. Azimuth ambiguity. Resolution of azimuth ambiguity is very important for - determination of magnetic field structure.

tender
Download Presentation

Azimuth ambiguity resolution from dBz/dz

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Azimuth ambiguity resolution from dBz/dz M. Kubo (ISAS/JAXA), K. Shimada (University of Tokyo), K. Ichimoto, S. Tsuneta (NAOJ) and SOT-team

  2. Azimuth ambiguity • Resolution of azimuth ambiguity is very important for • - determination of magnetic field structure. • - calculation of shear angle, current density, and helicity. • We try to resolve the azimuth ambiguity from only B = 0 with • no assumption (L. Wu & G. Ai, 1990, ACTA). • Magnetic fields must satisfy B = 0 . dBz/dz < 0 dBz/dz > 0 If we can know sign of dBz/dz, the azimuth angle is determined. We calculate the sign of dBz/dz by using (1) two different photospheric line profiles (Fe I 6301.5Å and Fe I 6302.5Å) (2) line-core and wing of one photospheric line profile (Fe I 6301. 5Å) Bx, By Bx, By

  3. dBz/dz from two different line profiles • We obtain two Bz values using Fe I 6301.5Å and Fe I 6302.5Å lines. • - SOT/SP obtains full stokes profiles of Fe I 6301.5Å and Fe I 6302.5Å. • Milne-Eddington inversion code is applied for each line • to derive the magnetic field strengths with different height. • Formation height of Fe I 6301.5Å is slightly higher than that of Fe I 6302.5Å. • Bz (6301.5Å) - Bz (6302.5Å) >0 •  dBz/dz > 0 • Bz (6301.5Å) - Bz (6302.5Å) <0 •  dBz/dz < 0 Stokes V profile

  4. Test Case • We use Holweger & Muller model atmosphere to make synthesized Stoke profiles. • Field strength has height gradient (dB/d =  300), • and inclination does not vary with height. • We examine 36 cases for dBz/dz >0 and 36 cases for dBz/dz <0. inclination: 0 = vertical to the solar surface, 90 = horizontal to the solar surface

  5. Result1 • A percentage of correct answers for both  dBz/dz is 39 % (14/36). • When filling factor becomes a free parameter, the percentage increases to 67% . • The percentage of correct answers are not improved when thermodynamic • parameters are fixed to values derived from both lines or when weight of • Stokes-V increases in the ME inversion. input parameters: ◇:  = 10 [deg] △:  = 45 [deg] ×:  = 80 [deg] red: dBz/dz > 0 blue: dBz/dz < 0 dBz/dz > 0 dBz/dz < 0 (Filling factor are fixed to 1 in this case.)

  6. Result1 • A percentage of correct answers for both  dBz/dz is 39 % (14/36). • When filling factor becomes a free parameter, the percentage increases to 67% . • The percentage of correct answers are not improved when thermodynamic • parameters are fixed to values derived from both lines or when weight of • Stokes-V increases in the ME inversion. input parameters: ◇:  = 10 [deg] △:  = 45 [deg] ×:  = 80 [deg] red: dBz/dz > 0 blue: dBz/dz < 0 dBz/dz > 0 dBz/dz < 0 (Filling factor are fixed to 1 in this case.)

  7. Difference of response function between line-core and wing • We investigate difference between two Bz • values derived from Stokes profiles • around line core and wing. • The line core profile represents magnetic fields • in the upper atmosphere in comparison with • magnetic fields derived from the wing. • Bz (line core) - Bz (wing) > 0  dBz/dz > 0 • Bz (line core) - Bz (wing) < 0  dBz/dz < 0 • The line core is defined as line center  70 mÅ. • The wing is defined as -300mÅ to -70 mÅ. • We use Fe I 6301.5Å, because a response • function of Stokes V to Bz for Fe I 6301.5Å • is sharper than that of Fe I 6302.5Å. Response function of Stokes-V to Bz Line center: 6301.5Å Stokes V profile (6301.5Å)

  8. Result2 • A percentage of correct answers for both  dBz/dz is 86 % (31/36), and • it increase to 97% (29/30) for field strength > 500 Gauss. • We may have to change wavelength sampling for line-core and wing • with a width of Zeeman splitting. input parameters: ◇:  = 10 [deg] △:  = 45 [deg] ×:  = 80 [deg] red: dBz/dz > 0 blue: dBz/dz < 0 dBz/dz > 0 dBz/dz < 0 (Filling factor and Doppler shift are fixed to 1 and 0 respectively in this case.)

  9. Summary and Future Works • Difference between the response functions of Stokes V for line-core • and wing would be useful for calculating the sign of dBz/dz. • - We have to test this method for • (1) many cases with various parameters (Doppler, filling factor..) • (2) profiles including noise • (3) observed Stokes profile • We like to find the best way to calculate the sign of dBz/dz. • - We will try to derive the sign of dBz/dz by using • (1) Neural network • (2) PCA • (3) Inversion with height gradient • (4) etc

  10. Stokes V profiles fitted for line core and wing A B C input line core wing

  11. Response function of Stokes-V to Bz, FeI6302.5A

  12. Response function of Stokes-V to Bz, FeI6301.5A

  13. l = -168 ~ +168mA

  14. 6301.5A 6302.5A

  15. FeI6302.5A Bt=100G Residual of ME fit

More Related