From: jgr-spacephysics@agu.org Date: Mon, 20 Mar 2006 16:25:22 UT To: xpzhao@solar.stanford.edu Subject: 2005JA011576 Decision Letter Manuscript Number: 2005JA011576 Manuscript Title: The success rate of predicting the heliospheric magnetic field polarity with MDI synoptic charts Dear Dr. Zhao: Below and/or attached are two reviews of the above manuscript. Both reviewers find this work significant and potentially suitable for publication in the Journal of Geophysical Research - Space Physics, but they have a number of comments that first need to be carefully addressed. Dr. Clia Goodwin, Editor's Assistant, has also lightly copyedited your manuscript and offered a few minor suggestions. If you wish to submit a revised manuscript, please do so by May 15, 2006. 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Sincerely, Amitava Bhattacharjee Senior Editor, Journal of Geophysical Research - Space Physics Reviewer Comments Reviewer #1(Comments): This paper describes the comparison between observed heliospheric magnetic field (HMF) with calculated HMF extrapolated using Potential Field Source Surface (PFSS) model from observed photospheric magnetic field synoptic charts as boundary condition. The comparison is made at the Earth distance with the data obtained by WIND and ACE. The study found that the MDI/SOHO synoptic charts generate the highest success rate at predicting the HFM represented by heliospheric current sheet (HCS). In sense of the extrapolating the heliospheric magnetic field using PFSS model, this is not the original work. Rather, this work attempts to improve existing method for predicting the HMF from photospheric magnetic field measurements. Mostly, the paper is not well written that authors should stress the following issues: 1). Why it is important to obtain HMF numerically while observational data are available near earth. 2). Exaplin how the spatial resolution of MDI synoptic charts are reduced. Are authors reducing the MDI resolutions in order to match the resolution of WIND and ACE? What is the magnetic resolution of WIND and ACE? 3). Why do authors choose magnetic synoptic charts duing maximum B0? Since polar fields are crucial for HCS profiles, would it be more accurate if the synoptic charts are used when B0 are minimum? At least, the polar fields would be observed instead of using the fitted values. 4). If polar fields are mostly radial, the line-of-sight magnetogram should show little signal at polar holes (0, and 180 degree) despite the magnetic field density increases with latitude. How do authors explain non-zero signal at polar hole? 5). Looking at only numbers, MDI, KPNO and WSO data do not differ much with the success rates within the uncertainties. Is it because WIND and ACE data have very low spatial resolution that those photospheric data set do not make difference? After all, the comparison is made to compare HCS between predicted by PFSS and the observed data from WIND and ACE. Does this mean that the high resolution data is not necessary for such comparison? Some minor comments: pp. 4, second line, two "and and" pp.9 5th line, "(see the middle panel of the top row)", which figure? In figure 2, the labels on each panel, \theta should be properly written. Reviewer #2(Comments): In this work, MDI synoptic charts for 8 years are used to predict the heliospheric magnetic field (HMF) polarity. First, data gaps in polar regions are filled in using the derived latitude-dependence of the zonal polar field. Then the potential field source surface (PFSS) model is employed in order to extrapolate the photospheric magnetic field represented by the MDI as well as KPNO and WSO synoptic charts into the corona. The results are compared to the daily HMF polarity observed by WIND and ACE, and the mean success rate of the prediction is quite high (84-86%) for all data sets. Significant work has been done and the results should be published, although a bit more effort must be put to make the paper helpful and clear, in particular for a broader audience. 1. Figures are overloaded with sometimes unnecessary details, whereas captions are not always very helpful and self-explanatory, e.g.: Fig. 2. All expressions for Br are same (Br is proportional to sin^8(\theta)) and only the coefficients differ. It would be enough to give the coefficients in each panel, while the expression could be moved to the caption. In my PDF version, 5th panel of the left column is empty. X- and Y- axes are not marked. Fig. 4. Blue and red colors are explained in the caption and there is no need of indicating that again in each panel. Same for MDI, KPNO and WSO (or once per column would be enough). Instead, the success rate could be moved to the top of each panel making plots less overloaded. 3d panel of the left column seems to be empty too (at least, in the PDF file I have). Although contours +-0.1 are explained in the text, it will be helpful if you describe them in the caption as well. Fig. 5. Mark X-axes (top and bottom). Explain dotted lines in caption. Table 1. Caption, please! 2. Abstract. "The mean success rate.. the best among the three data sources". Please, specify that the difference is small. 3. Section 2. More details would be helpful, e.g.: 1st paragraph: introduce B0. Which maps are used to derive the sin^8 dependence: high-resolution as stated in Summary (line 1) or reduced resolution (panels A or B of Fig. 1)? Last paragraph. Sentence "We obtain Bp using.." - give more details. Last paragraph. A brief description of KPNO and WSO synoptic charts would be helpful. E.g., in Summary you write that the resolution of the KPNO synoptic charts was also reduced to that of WSO. It is a bit late, I find. Section 2 would be a more suitable place. How do results depend on the resolution? 4. Section 3. OMNI web site: please, give url 5. Summary. 2nd paragraph: optimum N. If you find this important enough to be mentioned in the Summary, please remind the reader what N is and which value of N is used in this work. 3d paragraph: ".. over 12 years"?? June 1996 - June 2004? 3d paragraph: "most of the discrepancies occur in the day or two near the HCS crossing" - One can probably quantify this. You have the total number of days with false predictions. How many of these happen within 2 days around the HCS crossing? 6. Typos etc.: p.4 line 2 - "and and" p.6 last line - Panels.. showS p. 8 line 5 bottom - Borrini, et al. (skip ,) Summary line 2 - Sin^8, must be \sin^8 References: Hoeksema... 1982, Mikic & Linker 1996, and Svalgaard... 1975 are incomplete; Schatten 1971 (cited on p. 3), Wang & Sheeley 1995 (cited on p. 6), Chapman & Bartels 1962 (cited on p. 7) are missing --------------------IMPORTANT PUBLICATION INFORMATION--------------------- To ensure prompt publication: 1. Follow file format guidelines 2. Provide a color option 3. Combine figure parts or provide separate captions 4. Provide copyright permissions for reprinted figures and tables 5. Sign and send copyright transfer agreement 6. A formal estimate will be sent to you a few weeks after acceptance. For information on all of the above items, see Tools for Authors at http://www.agu.org/pubs/inf4aus.html. If you have any questions, reply to this e-mail. 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