Authors' response to referee1's comments

Thanks for reviewing the manuscript.
Here are referee1's comments started with '>' and authors' response started
with '***' after each comment.
>
>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.
>
*** 1). The in situ observation of HMF near the Earth provides only one
measurement at a specific time. The calculation can provides 2D or
3D distribution of the HMF polarity for a specific time. In addition, 
the calculated result may be used to predict the HMF polarity 3-5 days 
in advance and used as the initial condition in 3-D MHD simulations.
>
>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?
>
*** 2). As mentioned in paragraph 2 of Section 2, we use the nearest 
neightborhood
average (see, say, the IDL routine, SMOOTH.pro) to reduce the spatial
resolution of the MDI synoptic chart. It is well known that the 
HMF is determined by lower multipole magnetic moment (see Figure 3). It
is thus not necessary to use MDI high resolution data. 
The sector structure of the HMF was found for the dominated polarity of HMF,
i.e., the polarity of 3-hour average. What predicted now is usually for daily
average of the HMF. There is no any association with the 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.
>
*** 3). All original synoptic charts have data gap to be filled. 
The purpose to choose magnetic synoptic charts during maximum +B0 (-B0), 
when there are complete observations in the south (north) polar region, is
for obtaining the latitude-dependence of the longitude-averaged field
in the south (north) polar region (see Figure 2). Such obtained 
latitude-dependence is used for filling data gap in the south (north) polar
region for other B0 angle.
In calculating daily HMF polarity we use all 107 synoptic charts between
1996 and 2004 with data gap filled up.
>
>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?
>
*** 4). The north or south pole (not HOLE) with colatitude of 0 or 180
are the geometrically singular point in the format of synoptic charts.
No data value can be specified at the poles. For high resolution MDI
synoptic chart, data can be specified is between 2.47 and 177.53,
and it is between 6.04 and 173.96 for the grid of 360x180.
>
>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?
>
*** 5). The slight difference among the three data sources implys 
that all lower 
magnetic moments from three data sources can be used to represent
the real large-scale photospheric field, and thus to calculated coronal
and heliospheric magnetic field.
>
>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. 
> 
In the revised version, the three points have been corrected.