See Brief request syntax to understand each keyword.
ERA-40 Pressure levels
Relative humidity, 2m temperature, 10m u wind component, 10m v wind component. 60 levels. August 2002.
ECMWF Public Dataset web interface
#!/usr/bin/env python
from ecmwfapi import ECMWFDataServer
server = ECMWFDataServer()
server.retrieve({
'stream' : "oper",
'levelist' : "1/2/3/5/7/10/20/30/50/70/100/150/200/250/300/400/500/600/700/775/850/925/1000",
'levtype' : "pl",
'param' : "130.128/131.128/132.128/157.128",
'dataset' : "era40",
'step' : "0",
'time' : "00/06/12/18",
'date' : "2002-08-01/to/2002-08-31",
'type' : "an",
'class' : "e4",
'target' : "era40_2002-08-01to2002-08-31_00061218.grib"
})
ERA-40 Surface
2m temperature. February 2002.