What are reforecasts?
Reforecasts are forecasts run using the same model version as real-time forecast for a number of past dates. More details here.
How to access S2S data effectively?
In order to retrieve data efficiently users should follow instructions about S2S reforecasts retrieval efficiency.
Do you have any examples of Web API batch scripts for S2S data access?
Find links here to efficient retrieval scripts for different S2S datasets via ECMWF Web API.