The ECHAM 4.5 model is a dynamical atmospheric general circulation model (AGCM),
which has been forced with prescribed sea-surface temperatures (SSTs) in a two-tiered 
forecasting process. The AGCM is run at a resolution of T42, which converts to a 
resolution of 2.8125 degrees longitude and an approximate resolution of 2.8 degrees 
latitude. A total of 12 ensemble members are available in the hindcasts for 
generating probabilistic forecasts, although 24 members are available for the 
operational forecasts. The SSTs are prescribed by persisting the anomalies observed 
over the latest month without damping. The different initial atmospheric conditions
were obtained by a combination of random wind perturbations and lagged
averaging from runs prior to 1948, and then forcing the model with observed
SSTs upto the start date of the forecast.`

The parameters assessed are total precipitation and 2-metre temperature. Verification
results are provided for the global tropics, and the northern and southern hemisphere
extratropics (level 1). Maps (level 2) are provided for the whole globe. Lead-times
of 0-, 1-, and 2-months are available. The verification period is for initialization
dates from 1981-2001 (21 years), although hindcasts are available from 1968. The
model was verified at 2.5 degree resolution using the GPCP and CRU datasets provided
by the Lead Centres.