MISR Level 3 Aerosol (MIL3MAEN) data files empty?

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digbyr
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Joined: Fri Mar 05, 2021 7:51 pm America/New_York

MISR Level 3 Aerosol (MIL3MAEN) data files empty?

by digbyr » Fri Mar 05, 2021 8:01 pm America/New_York

I'm trying to analyze MISR Level 3 aerosol data (MIL3MAEN) for 2015-2020. It looks like the data for 2015-mid2017 comes with two file types:

(a) MISR_AM1_CGAS_0_5_DEG_MMM_YYYY_F08_0031.nc
and
(b) MISR_AM1_CGAS_MMM_YYYY_F15_0032.nc

From mid-2017 onwards, only the latter (b) are available. But the (b) file type does not seem to contain any data variables? For example, in python:

>> from netCDF4 import Dataset
>> nc = Dataset(MISR_AM1_CGAS_JAN_2015_F15_0032.nc)
>> print(nc.variables)

returns {} (an empty dictionary). And comparing the file sizes, type (a) are ~900Mb whereas type (b) are only ~50Mb. Is the data missing? or is there a different dataset, other than MIL3MAEN, that I should be using?

Thanks!

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ASDC - rkey
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Re: MISR Level 3 Aerosol (MIL3MAEN) data files empty?

by ASDC - rkey » Tue Mar 09, 2021 8:20 am America/New_York

Hello digbyr,

We've reached out to our MISR Subject Matter Expert and have received the following response:
I think they’re getting tripped up by the top level directories in the new MISR aerosol files. There aren’t any datasets in the top-level directory. My recommendation is they should be using MISR_AM1_CGAS_MMM_YYYY_F15_0032.nc, which is the latest product version. I usually use h5py to grab datasets, so that would look something like:

print("Reading: "+ filename)

file = h5py.File(filename, 'r')
dataset1 =file[Aerosol_Parameter_Average']['Aerosol_Optical_Depth']

Try using Panoply as a handy software to use to browse the file directory and choose the variables desired.
https://www.giss.nasa.gov/tools/panoply/
Hope this helps!

digbyr
Posts: 2
Joined: Fri Mar 05, 2021 7:51 pm America/New_York

Re: MISR Level 3 Aerosol (MIL3MAEN) data files empty?

by digbyr » Mon Mar 29, 2021 5:48 pm America/New_York

Thanks for the clarification! That did the trick.

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