Calibration of Polarization Data for Vector Magnetographs at the Huairou Solar Observing Station over the Past Four Decades
, Haiqing Xu 1,2,3,*, Suo Liu 1,2,3,*, Jiaben Lin 1,3, Hui Wang 1,2,3, Yongliang Song 1,3, Xianyong Bai 1,2,3, Shangbin Yang 1,2,3, Jie Chen 1,2,3, Xiaofan Wang 1,3, Yingzi Sun 1,3, Xiao Yang 1,3 and Yuanyong Deng 1,2,3Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis is a well written article on an important subject, worth publishing. I have only some minor comments:
- l. 143-145: Please add how many images were used for the estimate of the crosstalk amplitude and how many days they span.
- l. 244: What was the value given by Wang, J. X. et al.?
- Section 3 is not really a discussion of the results presented in the previous sections, as the authors present results of comparison of V from SMAT, SMFT, and FMG, and they consider the effects of varying Doppler velocity over the full solar disk. Please chose a more appropriate title
- Section 4: Please add some text on the importance and efficiency of the corrections presented in the previous sections. Are these corrections applied to the data provided to the scientific community or the users should make their own corrections? The section could be renamed "Summary and conclusions"
Comments on the Quality of English Language
Here are a few cases that stroke my eye:
- l. 36: "and solar winds" -> "and the solar wind"
- l. 245: "Nother" -> "Another"
- l. 286: "Farady" -> "Faraday"
Author Response
Dear Reviewer,
Please check author's reply in the attachment. Thank you.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsPlease look at the attached report.
Comments for author File: Comments.pdf
Author Response
Dear Editor,
Thank you so much for the incredible job you've done as the editor of my article. This article of ours mainly reviews the polarization calibration work conducted over the past 40 years at the Huairou Solar Observing Staion on the data observed by the instruments used in Huairou. One of the authors, Su Jiangtao, participated in most of these works, which may give an impression that there are more self-citations (~40%) in the article. However, Su Jiangtao did indeed participate in all of these works.
We are very grateful to the suggestions and comments by the referee. We have revised the manuscript based on the referee's comments. All the new changes in the manuscript are in bold font. Below is our point-by-point reply.
RESPONSES TO REVIEWER REPORTS
Reviewer Comments: Sections 2.1 and 2.2.1-2.2.2 are specific to the three instruments discussed, but sections 2.2.3-2.2.4 are common to any magnetograph. This point could be mentioned in section 1.
Our reply: We mentioned it in section 1 as “It's noteworthy that Sections 2.1 and 2.2.1-2.2.2 are tailored specifically to the three instruments under discussion, while Sections 2.2.3-2.2.4 serve as a common ground, transcending the boundaries of individual instruments.”.
As it is written below as specific points, I wonder why the authors do not calculate the expected signals based on the Unno-Rachkovsky formula.
Our reply: You are absolutely right! However, our observation instruments, from SMFT, STCT, SMAT, to FMG, observe polarization (Stokes QUV) at a single wavelength position of the spectral line, without polarization (Stokes QUV) profile data. Therefore, we cannot use theoretical model profiles to fit the observed profiles to invert the vector magnetic field.
Specific Points
Abstract: You may define the abbreviation HSOS at the beginning and should avoid repeating its full name many times.
Our reply: Thank you very much! We did it as you said.
Line 26: FMG on board the ASOS-S satellite launched in 2022
Line 36: solar winds → the solar wind
Line 43: The three instruments (SMFT[1], STCT, and AIMS) are designed to obtain …
Line 45: while SMAT[2], FMG[3], and SFMM…
Line 46: polarization at multiple wavelengths of the working spectral lines…
Line 47: only at one (wing) wavelength of the working spectral lines.
Our reply: Thank you very much! We corrected them in the manuscript.
Table 1: Please specify the field of view of each instrument. References should be given for STCT, SFMM, and AIMS.
Our reply: The field of view of each instrument is specified. We have included a reference for STCT, but the manuscripts containing detailed descriptions of SFMM and AIMS are currently in the preparation phase.
Line 59: This line is characterized by a Landé factor geff =1.5
Lines 58, 104: Vector Magnetographs → vector magnetographs
Line 63: H.Q.Zhang [6,7] noticed …
Line 71: To achieve rapid construction of a vector magnetogram, we routinely derive …
Line 73: established → assumed
Our reply: We corrected these errors.
Lines 80-102: On the other hand it may be said that the Fe 5324 A is a broad line and is less
sensitive to weak magnetic fields compared to narrower lines like 6303A.
Our reply: We add a paragraph in the paper “On the other hand, for the spectral line of λ 5324.185 Å, due to its large width, it exhibits relatively low sensitivity to weak magnetic fields. This implies that under weak magnetic field conditions, the shape and position of this spectral line may not undergo notable changes, rendering it challenging to accurately measure weak magnetic fields through observations of this spectral line alone. In contrast, narrow spectral lines such as λ 6302.5 Å are more sensitive to changes in magnetic fields, hence potentially more useful in magnetic field measurements. To overcome the limitation of FeI λ 5324.185 Å’s insensitivity to weak magnetic fields, in practice we employ a method of superimposing multiple frames of polarization images to enhance its sensitivity towards detecting weak magnetic fields.”
Line 80: It’s → It is
Line 83: are insignificant → have minor effects
Line 96: depends on the excitation potential …
Line 97: severely → highly
Our reply: We corrected these errors.
Lines 112-126: Here it may be stressed that all three instruments have straight light path up to the polarization analyzer, without oblique mirrors.
Our reply: We added a sentence in the text as like “In order to improve the measurement accuracy of the magnetic field and reduce the impact of polarization crosstalks, our instruments feature a straight light path leading directly to the polarization analyzer, without the use of oblique mirrors”.
Lines 116-117: Do you mean that errors related to KD*P occur because the KD*P may not produce retardation that is required in the design?
Our reply: Yes!
Line 117: By “retardation errors in quarter-wave plates” do you mean manufacturing errors, or undesirable effects produced by thermal or mechanical distortion? Such distortion and instrumental retardation may also be produced by prefilters, etc.
Our reply: We mean that they are manufacturing errors. Yes, thermal and mechanical distortion can also produce such retardation errors.
Line 119: Why do the authors not mention seeing-induced crosstalks (I to QUV by image motion) ?
Our reply: Thank you very much! We added a sentence in the text “Seeing-induced crosstalks (from I to Q, U and V) are induced by image motion caused by seeing conditions.”.
Line 129: uniform because the field of view is small
Line 152: wide-field element in the birefringent filter
Line 172: intuitive → by empirical means
Our reply: We corrected these errors.
Line 174: It is better to give specific formulae for Cq and Cu.
Our reply: Two specific formulae for Cq and Cu are given.
Line 239: J.X.Wang et al. [26]
Our reply: We corrected it.
Line 241: To give the file names is not adequate. URL or other information is necessary.
Our reply: We provide a website to download the data.
Line 245: Nother → Another
Line 257: linear calibration → weak-field approximation
Our reply: We corrected it.
Line 260: “We find that … not linear”; Nonlinearity itself is not a problem because the field strength first increases and may stay constant as we proceed inward from the outside of a sunspot.
Our reply: Thank you very much! We removed the biased words “We find that”.
Line 274, equation (2): “sign” should be in roman.
Our reply: We corrected it.
This equation is hard to understand; you might explicitly give the values a 1 , a 2 , c 1 , c 2 ? I assume that these values must satisfy c 1 +a 1 =c 2 +a 2 .
Our reply: For NOAA 11877, the values of a1 and a2 are 0.163 and -0.296, respectively, while c1 and c2 are 0.043 and 0.237, correspondingly. Similarly, for NOAA 12209, a1 and a2 are 0.108 and -0.146, respectively, and c1 and c2 are 0.023 and 0.143, correspondingly.
As can be seen, different correction coefficients are used for different active regions. As the reviewer mentioned, these corrections are quite arbitrary, so it is not appropriate to give their specific values in this equation.
Line 276: constants → intercepts
Our reply: We corrected it.
Line 283: “… has been corrected”; The procedure shown here looks rather arbitrary. Why do you not adopt theoretical models (Milne-Eddington etc.) to go beyond the weak-field approximation?
Section 2.2.2: The Faraday rotation effect is incorporated in the Unno-Rachkovsky formula, so that again I wonder why the authors do not consider a theoretical model to account for the Faraday rotation.
Our reply: You are absolutely right! However, our observation instruments, from SMFT, STCT, SMAT, to FMG, observe polarization (Stokes QUV) at a single wavelength position of the spectral line, without polarization (Stokes QUV) profile data. Therefore, we cannot use theoretical model profiles to fit the observed profiles to invert the vector magnetic field.
Line 370: is normal → looks reasonable
Figure 9 caption: Active Region → active region
Line 377: full-disk magnetographs
Line 380: heliographic coordinates
Our reply: We corrected them.
Figure 10: What are X and Y in panel b? If they are CEA longitude and latitude, how can they be converted to arcsec?
Our reply: Thank you very much! We corrected them into CEA longitude and latitude.
Figure 11 caption: Active Region → active region
Our reply: We corrected it.
Line 393: Is the coordinate system used (X and Y in Figure 12b) is a local Cartesian or spherical coordinate system? If the latter is the case, X and Y should be represented by (r, θ, Ï•).
Our reply: Thank you very much! We corrected them into CEA longitude and latitude.
Line 394: accurate and intuitive understanding → physical representation
Our reply: We corrected it.
Figure 12 caption: Active region → active region
(a) is the original (observed) vector magnetogram, and (b) is the magnetogram deprojected to the local Cartesian (or spherical) coordinate system.
Our reply: Thank you very much! We corrected it.
Lines 405-412: Gauss → gauss (or G)
Line 423: Su et al. [40]
Figure 13 caption: Active Region → active region
Lines 430-441: “drift” implies variations in time, but the phenomenon discussed here is
variations in space. A more appropriate term is simply “shift”.
Our reply: Thank you very much! We corrected them.
Line 475: Isn’t it appropriate to thank the founders and funding agencies of SMFT and SMAT, as well as the ASO-S project?
Our reply: Thank you very much! We revised it according to your suggestions.
Line 538: MMetcalf → Metcalf
Our reply: We corrected it.
Styles: This I presume will be taken care of by the Editorial Office, but it was unpleasant to see unconventional styles in reading the manuscript.
*Stokes parameters I, Q, U, V should be in italic.
*Subscripts L, T, and m should be in roman.
*Superscripts obs and pot should be in roman (lines 353, 354)
Our reply: Thank you very much! We corrected them.
*Italic U (U) looks strange but this is a matter at the publisher.
*Why do you use C q and C u instead of C Q and C U ?
Our reply: Thank you very much! We corrected them.
