We need to retrieve three types of files efficiently for the two reanalyses with experiment id = 21 and experiment id = 22. These are all class=ea. The three "streams" are oper, moda and mfb:
Stream: Atmospheric daily analyses (oper)
Stream: Monthly means of Daily Means (moda)
Stream: Observation departures for the data used in the reanalyses (mfb)