questions about HDF4 SDS data

Hi friends,

I want to plot the LW TOA Total-Sky field in *
CER_ZAVG_Aqua-FM4-MODIS_Edition2B_007005.200503.hdf* (you can find it at
ftp://ftp.hdfgroup.uiuc.edu/pub/outgoing/veer/MAP_DATA/files/CERES/CER_ZAVG_Aqua-FM4-MODIS_Edition2B_007005.200503.hdf).

My codes is in *CER_ZAVG_Aqua-FM4-MODIS_Edition2B_007005.200503.ncl* (in
attachment).

But I have some questions.

*Question 1:*
There are four LW TOA Total-Sky fields in this hdf file:
1.0 Degree Zonal -> Monthly Hourly Averages -> Observed TOA Fluxes -> LW TOA
Total-Sky
1.0 Degree Zonal -> Monthly Averages -> Observed TOA Fluxes -> LW TOA
Total-Sky
Global -> Monthly Hourly Averages -> Observed TOA Fluxes -> LW TOA Total-Sky
Global -> Monthly Averages -> Observed TOA Fluxes -> LW TOA Total-Sky

I found from
http://www.ncl.ucar.edu/Document/Manuals/Ref_Manual/NclFormatSupport.shtml that
I probably can use
data = hdf_file->LW_TOA_Total_Sky__0 to specify 1.0 Degree Zonal -> Monthly
Hourly Averages -> Observed TOA Fluxes -> LW TOA Total-Sky,
and use data = hdf_file->LW_TOA_Total_Sky__1, data =
hdf_file->LW_TOA_Total_Sky__2, data = hdf_file->LW_TOA_Total_Sky__3 to
specify the other three LW_TOA_Total_Sky fields.

But, can I use something like
data = hdf_file->LW_TOA_Total_Sky__Observed_TOA_Fluxes__
Monthly_Hourly_Averages __1_0_Degree_Zonal to specify the LW TOA Total-Sky
field? Because I just want to explicitly show the full path.

*Question 2:*
There are several sentences in
http://www.ncl.ucar.edu/Document/Manuals/Ref_Manual/NclFormatSupport.shtml
saying
that "It also provides two additional attributes to the variable: *hdf_group
*, whose value is the HDF string name of the group, and *hdf_group_id*,
whose value is the same as the group number appended to the end of the
variable name."

Can I use something like printVarSummary() to print out the information
about hdf_group and hdf_group_id (Let us still take 1.0 Degree Zonal ->
Monthly Hourly Averages -> Observed TOA Fluxes -> LW TOA Total-Sky as an
example) ? If not, how can I get the hdf_group and hdf_group_id
information?

*Question 3:*

I used my codes to get a plot (see *
CER_ZAVG_Aqua-FM4-MODIS_Edition2B_007005.200503_LW_TOA_Total_Sky.pdf* in the
attachment). However, if I hope the range of X-axis (latitude) is -89.5~89.5
(not 0~179), and the range of Y-axis is 0~7 (not 0.0~7.0). How can I change
the codes?

In addition, there is an overlap in the subtitles, how to avoid it (I hope
it can only shows "FIELD NAME: LW TOA Total-Sky" and "UNITS: Watt per
square meter" as the subtitles) ?

Thanks a lot!

Best,
Yi

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