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Seasonal forecast monthly means and monthly
mean anomaly dissemination products
In
addition to the directly produced model output, the seasonal
forecasting system produces a range of derived data which are also
available for dissemination. Firstly, there are forecast monthly
mean products (STREAM=MSMM). These are created for each field and
each ensemble member, and are available for each of the 7 calendar
months of the forecast integration. For most surface fields,
monthly mean values, monthly maximum values (i.e., for each grid
point the maximum value of the field output during the month),
monthly minimum values and monthly standard deviations are created.
All of these statistics are derived from the direct model output,
i.e. the fields sampled every 6, 12 or 24 hours, and thus do not
include variations on timesteps shorter than this.
As
well as the monthly mean values of fields for each ensemble member
(TYPE=FCMEAN), the ensemble mean (TYPE=EM) of each field is
available, again for each of the 7 calendar months of the
forecast.
The
daily and monthly fields from the seasonal forecast model must be
interpreted in the context of previous model forecasts, due to the
substantial impact of model errors. If only forecast anomalies are
wanted, then instead of processing the latest forecast output
together
with the set of previous forecasts, it is
possible to request pre-calculated monthly mean anomalies
(STREAM=MMSA). These are anomalies with respect to the forecast
model climate for 1987-2001, and are available as forecast monthly
means for each of the 7 calendar months, both for the individual
ensemble members and as an ensemble mean.
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