Is this the most efficient way to download "mtdch" from "reanalysis-era5-complete"?

Software and Tools API
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Hello,

I am trying to download the parameter “mtdch” at model level 137 (param code 235014) from “reanalysis-era5-complete” using the CDS API.

I read somewhere that I should not request data on more than one tapes within a single MARS request. The ERA5 Catalogue indicates that mtdch records for each calendar day are “stored in one file on tape” (see screenshot below).

image
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Therefore, to retrieve all records from year 2000 to 2021, I am looping my requests at the calendar day level. The following is the python code snippet I am using:

for day in calendar_days:
            c.retrieve("reanalysis-era5-complete", {
                "class": "ea",
                "date": day,
                "expver": "1",
                "levelist": "137",
                "levtype": "ml",
                "param": "235014",
                "step": "1/2/3/4/5/6/7/8/9/10/11/12",
                "stream": "oper",
                "time": "06:00:00/18:00:00",
                "type": "fc",
                'format': 'netcdf',
                "grid": [0.281, 0.281], 
                "area": [40, -180, -40, 180]
            }, output_path)

The requests do run to completion without problem but they are quite slow, usually taking 30 minutes or more to retrieve a single calendar day.

So my question is, is this already the most efficient way of retrieving this parameter?

Any help is much appreciated.

Many thanks,
KH