Collocating CALIPSO CAL_LID_L2 and ECHAM-HAM

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Bernd Heinold
Collocating CALIPSO CAL_LID_L2 and ECHAM-HAM

Hi,

I wonder whether the collocation function of CIS also works for collocating vertical profiles of CALIPSO and ECHAM-HAM model output.

So far, I have tried:

cis col Extinction_Coefficient_532:CAL_LID_L2_05kmAPro-Prov-V3-01.2010-05-03T12-42-33ZD_Subset.hdf model_file.nc:variable=DU_AS -o outfile

which however gives:

"2017-08-02 14:54:33,954 - ERROR - A sample variable has been specified but not all coordinates in the data appear in the sample so there are multiple points in the sample data so whether the data is missing or not can not be determined."

When adding a vertical pressure coordinate to the model_file.nc, which by default only contains unitless indices of a hybrid vertical coordinate and sfc pressure, the command succeeds BUT the output file only contains fill values.

Am I missing something here or is this simply not supported?

Many thanks in advance,
Bernd

duncanwp
Re: Collocating CALIPSO CAL_LID_L2 and ECHAM-HAM

Hi Bernd,

Yes, this is exaclty the kind of thing CIS can help with, although there are some caveats in this case. As you noticed ECHAM-HAM output doesn't always include the pressure coordinate. In principle CIS can reconstruct this from the hybrid coordinates, however (depending on which version of ECHAM you're using) these don't have CF compliant formula terms and so we can't do this out-of-the-box.

Once you have the pressure coordinate it should work though - assuming that the pressure coordinates are in the same units! In future versions of CIS it will at least check that the units are compatible, and perhaps perform a conversion, but for now you have to do this yourself. (This mostly only affects altitude and air pressure as lat/lon are always in degrees and the time unit conversion is taken care of for you already).

I use ECHAM-HAM a lot, so I have a plugin for reading the model output and creating the correct pressure levels in hPa here: https://github.com/duncanwp/cis_plugins/blob/master/echam_ham.py, you will also need this one: https://github.com/duncanwp/cis_plugins/blob/master/echam_ham_pascals.py. (There's an echam_ham_63.py one too if you're using the latest version of ECHAM-HAM.) If you download these and set the CIS_PLUGINS_HOME environment variable to point to the folder they're in, you should be able to do:

cis col
Extinction_Coefficient_532:CAL_LID_L2_05kmAPro-Prov-V3-01.2010-05-03T12-42-33ZD_Subset.hdf
model_file.nc:variable=DU_AS,product=ECHAM_HAM_63 -o outfile

Hope that helps!

Duncan

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