Soil Moisture: spurious "Request too large" errors

[pont-us]

Consider, for example, the following request:

generated_cube = cds_store.open_data(
    'satellite-soil-moisture:volumetric:monthly',
    variable_names=['volumetric_surface_soil_moisture'],
    time_range=['2015-01-01', '2016-01-31']
)

This requests a modest three months at monthly resolution, but at time of writing results in the following error from the CDS API backend:

2021-04-12 13:53:46,053 ERROR Message: the request you have submitted is not valid
2021-04-12 13:53:46,054 ERROR Reason:  Request too large. Requesting 17856 items, limit is 12000

This request worked as recently as 2021-02-18, and the relevant parts of the CDS Store code have not changed since then, so evidently something has changed in the CDS server's implementation of its undocumented API.

Closer examination reveals that the actual request sent by the CDS store includes the following:

'time' = ['00:00', '01:00', '02:00', '03:00', '04:00', '05:00', '06:00', '07:00', '08:00', '09:00', '10:00', '11:00', '12:00', '13:00', '14:00', '15:00', '16:00', '17:00', '18:00', '19:00', '20:00', '21:00', '22:00', '23:00'],
'day' = ['01', '02', '03', '04', '05', '06', '07', '08', '09', '10', '11', '12', '13', '14', '15', '16', '17', '18', '19', '20', '21', '22', '23', '24', '25', '26', '27', '28', '29', '30', '31']

This should not be there for a monthly average request. Presumably it was just ignored by previous versions of the CDS API. Removing the time parameter and setting day appropriately (according to the requested time-span and averaging period) would probably fix the bug.