UDA reduced catalog for cloud analysis

[aradhakrishnanGFDL]

Generate a UDA catalog that has at least the following fields to work with the new analysis script Clouds

requests three variables at monthly resolution
high_cld_amt
low_cld_amt
mid_cld_amt

thanks @ceblanton and @meteorologist15 for the details

https://github.com/NOAA-GFDL/analysis-scripts/blob/main/freanalysis_clouds/freanalysis_clouds/init.py
requests three variables at monthly resolution
high_cld_amt
low_cld_amt
mid_cld_amt

By good fortune, monthly ERA5 observations for high, medium, and low cloud cover are available:
/uda/ERA5/Monthly_Averaged_Data_On_Single_Levels/reanalysis/global/annual_file-range/Clouds/cloud_cover_high/
/uda/ERA5/Monthly_Averaged_Data_On_Single_Levels/reanalysis/global/annual_file-range/Clouds/cloud_cover_medium/
/uda/ERA5/Monthly_Averaged_Data_On_Single_Levels/reanalysis/global/annual_file-range/Clouds/cloud_cover_low/

[aradhakrishnanGFDL]

@meteorologist15 and @ceblanton

Looking at the analysis script, adding the attributes that we will need for the identified cloud variables.

1. realm (but its not in your DRS, so hard coding atmos is fine with comments for project="uda" and experiment_id="something" that says its ERA5 reanalysis.
2. Analysis script assumes time 1980 ( we are good here for this particular case)
3. frequency: edit config file to include frequency as its in the filename. Make sure catalog builder translates monthly to mon as it supports cmip frequency which the workflow also eventually will use.
4. variable_id (either short names or the standard names and we can make it work )

           "varlist": {
                "high_cld_amt": {
                    "standard_name": "high_cloud_fraction",
                    "units": "%",
                    "dimensions": ["time", "lat", "lon"]
                },
                "low_cld_amt": {
                    "standard_name": "low_cloud_fraction",
                    "units": "%",
                    "dimensions": ["time", "lat", "lon"]
                },
                "mid_cld_amt": {
                    "standard_name": "middle_cloud_fraction",
                    "units": "%",
                    "dimensions": ["time", "lat", "lon"]
                }

https://github.com/NOAA-GFDL/analysis-scripts/blob/main/freanalysis_clouds/freanalysis_clouds/__init__.py