Atmospheric Model Ensemble 15-day forecast (ENS), III-vii-a: Ensemble standard deviations - Single level

The spread of the ENS forecast, measured by the standard deviation (Std) of ENS values at a given point and lead time, is normalised against the mean of the spread of the 30 most recent 00UTC ENS (Mstd) for 00UTC runs (or 12UTC ENS (Mstd) for 30 most recent 12UTC ENS runs) for the same lead-times and geographical locations.