[ncl-talk] CNL read CALIPSO v4.51 data

[Dave Allured - NOAA Affiliate]

Where is the documentation for CALIPSO files?


On Thu, Sep 4, 2025 at 4:03 PM Dave Allured - NOAA Affiliate <
dave.allured at noaa.gov> wrote:

> HDF4, that is a good clue.  The dump utility for HDF4 is "hdp".  Do you
> have it?   There are many options.  To start, try "hdp -H list" and go from
> there.
> https://support.hdfgroup.org/hdf4/
>
> Note that HDF4 tools include an HDF4 to HDF5 converter, which they
> recommend.
>
> NCL addfile might be identifying this file as HDF-EOS, which is based on
> HDF4.  See addfile documentation.  Try switching the filename extension
> from .hdf to .he4 and see if that improves NCL readability.
>
>
> On Thu, Sep 4, 2025 at 3:39 PM Rick Brownrigg <brownrig at ucar.edu> wrote:
>
>> h5dump can't open it.  Running "strings" on that filename indicates its
>> an HDF4.2 file?
>>
>>
>> On Thu, Sep 4, 2025 at 3:30 PM Dave Allured - NOAA Affiliate via ncl-talk
>> <ncl-talk at mailman.ucar.edu> wrote:
>>
>>> More diagnostics needed.  Someone please show output from:
>>>
>>> NCL:
>>> fh = addfile("CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-
>>> 00-11ZD.hdf","r")
>>> print (fh)
>>>
>>> Linux:
>>> h5dump -BH CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-00-11ZD.hdf
>>>
>>>
>>> On Thu, Sep 4, 2025 at 3:23 PM Rick Brownrigg via ncl-talk <
>>> ncl-talk at mailman.ucar.edu> wrote:
>>>
>>>> Hi,
>>>>
>>>> As that file resides on /glade, I was able to access it and duplicate
>>>> the problem. I can print() that variable, but I can't load it into an NCL
>>>> variable. Its rather large -- 699MB. Perhaps that's the problem?
>>>> Interestingly, if I run "ncdump" on that file, I get:
>>>>
>>>>  ncdump
>>>> /glade/derecho/scratch/zhifengy/data/experiment_input/doe_cloud_africa/CALIPSO/CAL_LID_L2_VFM-Standard-V4-51/test/CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-00-11ZD.hdf
>>>>
>>>> ncdump:
>>>> /glade/derecho/scratch/zhifengy/data/experiment_input/doe_cloud_africa/CALIPSO/CAL_LID_L2_VFM-Standard-V4-51/test/CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-00-11ZD.hdf:
>>>> NetCDF: Attempt to use feature that was not turned on when netCDF was built.
>>>>
>>>> Rick
>>>>
>>>>
>>>> On Thu, Sep 4, 2025 at 3:16 PM Ehsan Taghizadeh via ncl-talk <
>>>> ncl-talk at mailman.ucar.edu> wrote:
>>>>
>>>>> Hi Zhifeng,
>>>>>
>>>>> Could you please add the following commands before your addfile
>>>>> command:
>>>>>
>>>>> exists =
>>>>> isfilepresent("CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-00-11ZD.hdf")
>>>>> print (exists)
>>>>>
>>>>> I wonder if your ncl script and the file are in the same place.
>>>>> In case it returns True, could you please add the following commands
>>>>> just after reading your file (after addfile command):
>>>>>
>>>>> names = getfilevarnames(
>>>>> "CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-00-11ZD.hdf")
>>>>> print (names)
>>>>>
>>>>>
>>>>> *-----------------------------------------------------------------------------*
>>>>> *Best regards,*
>>>>> *Ehsan Taghizadeh*
>>>>>
>>>>> On Thursday, September 4, 2025 at 01:37:05 PM PDT, Zhifeng Yang via
>>>>> ncl-talk <ncl-talk at mailman.ucar.edu> wrote:
>>>>> Hi all,
>>>>>
>>>>> I am using NCL 6.6.2 to read CALIPSO latitude, longitude, and
>>>>> Feature_Classification_Flags variable from CAL_LID_L2_VFM-Standard-V4-51.
>>>>>
>>>>>   fh =
>>>>> addfile("CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-00-11ZD.hdf","r")
>>>>>    lath      = fh->Latitude(:, 0)
>>>>>    lonh      = fh->Longitude(:, 0)
>>>>>    vfmh      = fh->Feature_Classification_Flags
>>>>>
>>>>> However, I got the error below
>>>>> fatal:HDF: An error occurred while attempting to read variable
>>>>> (Feature_Classification_Flags) from file
>>>>> (/glade/derecho/scratch/zhifengy/data/experiment_input/doe_cloud_africa/CALIPSO/CAL_LID_L2_VFM-Standard-V4-51/test/CAL_LID_L2_VFM-Standard-V4-51.2017-08-21T14-00-11ZD.hdf)
>>>>>
>>>>> Do you have any idea about this? Thanks,
>>>>>
>>>>> Best,
>>>>> Zhifeng
>>>>>
>>>>
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