Seasonal forecast monthly means and monthly mean anomaly dissemination products

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Description of System 3

Re-forecasts and pre-operational data

Seasonal forecast dissemination products

Seasonal Forecasting System 3 dissemination requirements

Seasonal forecast monthly means and monthly mean anomaly dissemination products

GRIB section 1 definition for Seasonal Forecast System 3 data

Transmission of Seasonal Forecasting System 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.

Products range

Available products are listed in the Table 10.2 bellow.

Table 10.2
* Not for TYPE=FCMIN (STREAM=MSMM);

FIELD CODE	MARS ABBREV.	FIELD NAME	UNITS	NO. OF BITS/VAL.
31	CI	Sea Ice Cover	m	16
33	RSN	Sea Dencity	K	16
34	SSTK	Sea Surface Temperature	K	16
39	SWVL1	Volumetric Soil Water layer 1	m3m-3	12
40	SWVL2	Volumetric Soil Water layer 2	m3m-3	12
41	SWVL3	Volumetric Soil Water layer 3	m3m-3	12
42	SWVL4	Volumetric Soil Water layer 4	m3m-3	12
49	10FG	Wind gust at 10 meters	m/s	16
51	MX2T24	Max 2m Tem. since past 24H	K	12
52	MN2T24	Min 2m Tem. since past 24H	K	12
78	TCLW	Total Column Liquid Water	kg m**-2	16
79	TCIW	Total Column Ice Water	kg m**-2	16
129	Z	Geopotential	m2s-2	16
130	T	Temperature	K	12
131	U	U-velocity	m/s	12
132	V	V-velocity	m/s	12
133	Q	Specific humidity	kg/kg	12
137	TCWV	Total column water vapour	kg m**-2	16
138	VO	Vorticity	s-1	16
139	STL1	Soil Temperature Level 1	K	12
139	ST	Surface temperature	K	12
141	SD	Snow depth	m	12
142	LSP	Large scale precipitation *	m	16
143	CP	Convective precipitation *	m	16
144	SF	Snow fall *	m	16
146	SSHF	Surface sensible heat flux	Wm**-2s	12
147	SLHF	Surface latent heat flux	Wm**-2s	12
151	MSL	Mean sea level pressure	Pa	12
155	D	Divergence	s-1	16
164	TCC	Total cloud cover	(0-1)	8
165	10U	10 metre U	m/s	12
166	10V	10 metre V	m/s	12
167	2T	2 metre temperature	K	12
168	2D	2 metre dewpoint temperature	K	12
169	SSRD	Surface solar radiat. downwards	W m**-2 s	16
170	STL2	Soil Temperature Level 2	K	12
175	STRD	Surface thermal radi. downwards	W m**-2 s	16
176	SSR	Surface Solar Radiation	W m**-2 s	16
177	STR	Surface Thermal Radiation	W m**-2 s	16
178	TSR	Top Solar Radiation	W m**-2 s	16
179	TTR	Top Thermal Radiation	W m**-2 s	16
180	EWSS	U-stress	Nm**-2	12
181	NSSS	V-stress	Nm**-2	12
182	E	Evaporation	m of water	16
183	STL3	Soil temperature level 3	K	12
186	LCC	Low cloud cover	0-1	8
189	SUND	Sunshine duration	s	16
3	PT	Potential Temperature	K	16
60	PV	Potential Vorticity	m2s-1Kkg-1	16
205	RO	Runoff	m	16
207	10SI	10 metre scalar wind speed	m/s	12
228	TP *	Total precipitation	m	16
236	STL4	Soil temperature level 4	K	12
243	FAL	Forecast albedo	0-1	8

Horizontal resolution

- 1.5 x 1.5 degrees latitude-longitude grid, or multiples thereof

- any spectral truncation (default T159)

- Gaussian grid (default N80) both regular and reduced

- any sub-area

Vertical resolution

- pressure levels 1000, 925, 850, 700, 500, 400, 300, 200, 100, 50 and 10 hPa

Verifying times

- forecast month 1 to 7

Potential Vorticity level products are available on the level 2000 as parameter PT. Potential Temperature (Isentropic) level products are available as parameter PV on levels 315 and 330.

Surface fields (Table 10.2) are available for FCMONTH 1 to 7, with TYPE = FCMEAN, FCMAX, FCMIN and FCSTDEV for individual ensemble members and TYPE = EM for the ensemble. Please, note that parameters LSP, CP, SF and TP are not available for TYPE = FCMIN.

Pressure level fields (Table 10.2) are available for FCMONTH 1 to 7, with TYPE = FCMEAN for individual ensemble members and TYPE=EM for the ensemble.

Seasonal forecast monthly means and monthly mean anomaly dissemination requirements

The following command language parameters are specific for the seasonal forecast monthly mean requirements. Other DIS parameters are listed under the 10.3 above.

Identification parameters

STREAM	=	MULTIMODEL SEASONAL FORECAST MEANS MULTIMODEL SEASONAL FORECAST MEAN ANOMALIES		[MSMM] [MMSA]
ORIGIN	=	ECMWF	[ECMWF]]
TYPE	=	FORECAST MEAN FORECAST MAX FORECAST MIN ENSEMBLE STANDARD DEVIATION ENSEMBLE MEAN	[FCMEAN] [FCMAX] (only for STREAM=MSMM) [FCMIN] (only for STREAM=MSMM) [FCSTDEV](only for STREAM=MSMM) [EM]
NUMBER	=	n-ENSEMBLE NUMBER OFF for TYPE=EM	[0-40]

Date and time parameters

STEP

OFF

FCMONTH

* (forecast month)

1/2/3/4/5/6/7;.

NB ALL, is not permitted.

08-02-2010