TIGGE data from Met Office, UK – November 2014 update
SummaryThe TIGGE dataset now includes data from the higher resolution, 7-day MOGREPS-G globalensemble (rather than MOGREPS-15, as used up to 00Z 15th July). The new data are being
thprovided in near-real time from 00Z 6 November, and it is planned to back-fill the missing data indue course. MOGREPS-G includes 12 members run four times a day. The number of TIGGE
parameters available from the new MOGREPS-G feed is significantly reduced.
Details
The Met Office TIGGE data is now taken from the higher-resolution short-range global ensemble,MOGREPS-G, rather than the medium-range ensemble system MOGREPS-15. This is part of acontinuing Met Office strategy to wind down its focus on 'week 2' and concentrate instead on'week 1' and monthly/seasonal forecasting. The Met Office is committed to using ECMWF data
and data from our UM partners and other data centres going forward for the medium-range as
defined by the forecast period days 7-14.
MOGREPS-G is a 33km, 70 level (N400L70) global ensemble system, which is run 4 times a daywith 12 members (1 control + 11 perturbed members) on each cycle run to T+174 (7 days, 6hours). The majority of our products from this system then use 6-hour lagging to create updated
24 member ensembles, enabling products to be produced out to 7 days (T+168). The TIGGE
data includes 12 members run to T+174 four times a day.
MOGREPS-G includes a range of significant science changes, notably the use of the new“ENDGAME” dynamical core, which is a grid-point, semi-implicit, semi-Lagrangian scheme whichcontains some significant improvements over the previous “New Dynamics”. Several otherchanges the physical parameterizations have been introduced in conjunction with ENDGAME –together they make up the GA6 (Global Atmosphere version 6) version of the Unified Model.
thMOGREPS-G was extended from a 3-day ensemble to a 7-day ensemble on 15 July, and fromthat point the TIGGE archive ceased to be fed from MOGREPS-15. Work was then undertaken toproduce MOGREPS-G output data in GRIB2 format and to TIGGE specifications. The new data
thare being delivered in near real-time starting 00Z 6 November. The number of parameters
available from MOGREPS-G are significantly reduced; the parameters dropped are, in summary,soil moisture & related fields; CAPE & CIN, total column water, U & V on PV surface, and specifichumidity on pressure levels. At a later stage, it is hoped to introduce additional customisations tore-introduce the humidity and wind on PV surfaces. It is planned to fill in the missing dates (from12Z 15th July to 18Z 5th November) in due course – but with a reduced set of fields, since theparameters customised for TIGGE are not available.
MOGREPS-15 is now scheduled for retirement in about a year (during FY 2015/16). In July 2014,
MOGREPS-15 was updated in line with MOGREPS-G (including GA6 changes), but since themodel has been 'frozen' with no further changes anticipated. A project to move remaining
downstream products to other models is already underway and will carry on for the rest of thisfinancial year and the beginning of next. When all services have been successfully moved,
MOGREPS-15 will then be switched off.