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


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).

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,