Observation extraction and processing can be considered as the first logical component. Any forecast run will usually start with the extraction and quality control of observations, usually in standard WMO code format, from online storage. Assimilation is the process by which current observations are incorporated into a model to provide an accurate representation of the atmosphere. A second important form of post-processing is verification of the forecast data which has been produced. The need to deliver forecast products to customers on time means that various forecasts must be started according to a daily Operational Suite schedule.
Every effort is made to adhere to the starting times.
The ending times should be used for guidance only and depend on a number of factors, such as how busy the computer is. End times are met except in circumstances such as a computer failure. The OS daily schedule is subject to alteration from time to time in order to meet new requirements such as additional model or forecast runs. In theory, such models could be left to run with no external influences, but, in practice, observational data in various forms are required to keep the model in line with the current meteorological conditions. From the schedule in Figure 1 it can be seen that there are six global runs per day.