[ncl-talk] fatal error reading variables from CALIPSO hdf file

[Rick Brownrigg]

Hi Zhifeng,

There are two variables in that file that cause this error when trying to
read them, and suspiciously enough, they are both of type ushort. I can
tell that error is coming from the HDF library, but I don't have an
environment where I can tell why. Using strace, it appears as though the
data are actually getting read from the file, but no insights as to why
ultimately an error code is returned to NCL.  I'm using hdf-4.2.11 -- there
is a newer hdf-4.2.13, but the release notes don't indicate a problem of
this nature has been resolved.

As a work around, I wondered about converting the HDF4 into either netcdf4
or hdf5. I tried using our ncl_convert2nc, but it complained with several
errors.  Perhaps there are other tools out there you might be aware of for
converting HDF4 files?

I'm sorry, I wish I had a better answer for you, but I've hit a dead end on
this.

Rick


On Fri, Jan 19, 2018 at 8:34 AM, Zhifeng Yang <yangzf01 at gmail.com> wrote:

> Hi Rick,
>
> I am sorry that I just saw your email. By following your instruction, I
> just uploaded a CALIOP hdf file onto the ftp. Here is the file info (size
> and file name)
>
> 42M CAL_LID_L2_VFM-Standard-V4-10.2015-06-08T08-02-42ZN.hdf
>
> Thank you
> Zhifeng
>
>
> On Thu, Jan 11, 2018 at 4:04 PM, Rick Brownrigg <brownrig at ucar.edu> wrote:
>
>> Hi,
>>
>> There has been some considerable work done since 6.4.0 on HDF support.
>> Are you able to share this file with us?  If its too big to email to me
>> (directly), then you can use our FTP site -- see details at:
>>
>> http://ncl.ucar.edu/ftp_files.shtml
>>
>> Rick
>>
>> On Thu, Jan 11, 2018 at 12:23 PM, Zhifeng Yang via ncl-talk <
>> ncl-talk at ucar.edu> wrote:
>>
>>> Hi all,
>>>
>>> I am using NCL to read the CALIPSO VFM level 2 file. However, I got an
>>> error while reading the variable "Feature_Classification_Flags". Here
>>> is the error in detail.
>>>
>>> fatal:HDF: An error occurred while attempting to read variable
>>> (Feature_Classification_Flags) from file (/home/vy57456/zzbatmos_common
>>> /Data/MODIS/6/llj_eus/CALIOP/CAL_LID_L2_VFM-Standard-V4-10/C
>>> AL_LID_L2_VFM-Standard-V4-10.2015-06-10T07-50-24ZN.hdf)
>>>
>>> The code is like
>>>
>>>     dirh      = "./"
>>>     nameh  = "CAL_LID_L2_VFM-Standard-V4-10.2015-06-10T07-50-24ZN.hdf"
>>>     fh         = addfile(dirh+nameh, "r")
>>>     vfmh     = fh->Feature_Classification_Flags(:, :)
>>>
>>> The NCL version is 6.4.0
>>> When you are available, would you please help me to figure this out?
>>> Thank you
>>>
>>> Best,
>>> Zhifeng
>>>
>>>
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>>
>
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