© Crown copyright Met Office Report to 21st NAEDEX Meeting Roger Saunders, Met Office, Exeter

© Crown copyright Met Office Met Office Operational Models : 2008  Global ~40km ~50Level  North Atlantic/Europe 12km ~50level  UK 4km(1.5km) ~50Level  Re-locatable Defence and Civilian  Ensemble (global & regional) at half horizontal resolution 25 members each  Data assimilation 4DVar, 6 hour window for global and regional models

© Crown copyright Met Office Planned NWP model changes ModelNow Global40km 25km 18km 50 levels70 levels 100 levels N At Eur12km8km 5km 50 levels70 levels 100 levels UK4km1.5km ~0.8km 50 levels70 levels 100 levels Specialist 0.25km 100 levels

© Crown copyright Met Office Supercomputing - NEC SX6, SX8 [2004-March 2009] IBM Power 5 & Power 6 [Nov > See Theoretical peak power of 16 billion calculations per second per processor

© Crown copyright Met Office IBM Power 5 & 6 Supercomputer Phased upgrade during x initial speed-up Phase 2 in 2011, further 3x increase on initial. Funded on ‘UK PLC’ (not Met Office) cost-benefits Funding from Met Office, Govt stakeholders and NERC contributions 1.2 MWatt 125 TFLOP (23 fold inc)

© Crown copyright Met Office How we get the data Global US data Local reception EUMETCASTGlobal Networks

© Crown copyright Met Office Observations assimilated Observation groupObservation Sub-groupItems usedDaily extracted% used in assimilation Ground-based vertical profiles TEMP PILOT PROFILER T, V, RH processed to model layer average As TEMP, but V only ,93, Satellite-based vertical profiles METOP-A NOAA-15/16/18, Aqua AIRS, IASI, HIRS, AMSU-A/B, MHS, DMSP-SSMIS Radio-occultation COSMIC, Champ, Grace, GRAS Radiances directly assimilated with channel selection dependent on surface instrument and cloudiness. Profiles of refractive index ATOVS:4,000,000 IASI: 324,00 AIRS:324,000 COSMIC: 1600 GRAS: 600 CHAMP+Grace: Aircraft Manual AIREPS Automated AMDARS T, V as reported with duplicate checking and blacklist ,000 17, 16 28, 2 Satellite atmospheric motion vectors GOES 11,12 BUFR Meteosat 7, 9 BUFR MTSAT BUFR MODIS, AVHRR polar AMVs High resolution IR winds IR, VIS and WV winds AVHRR AVHRR 8 Satellite-based surface winds DMSP-SSM/I-13 Seawinds ERS-2 scatt, METOP ASCAT In-house 1DVAR wind-speed retrieval NESDIS retrieval of ambiguous winds. Ambiguity removal in 4DVAR. 3,000,000 1,800,000 ERS-2 not incuded 1,500, Ground-based surface Land SYNOP SHIP Fixed Buoy Drifting BUOY GPS IWV Pressure only (processed to model surface),V,T,RH P,V,T,RH P,V,T P Total column water ,87,87,86 93,94,94,94 87,85, Cloud/Rain observations METEOSAT-9 SEVIRI and UK rain radar network Nimrod – MOPS cloud in NAE rain cloud 100

© Crown copyright Met Office Satellite delays May 2007 Aug 2008 Aqua degraded

© Crown copyright Met Office AIRS delays Mean Mode Min

© Crown copyright Met Office Recent changes to usage of data METOP ASCAT surface winds assimilated from Nov 07 METOP IASI radiances (~138 channels) assimilated Nov 07 AVHRR polar winds assimilated May 08 METOP GRAS (GPS RO) assimilated from July 08 Modified AMV observation errors to take account errors of height assignment New OSTIA SST and sea-ice analysis operational SST analysis uses, AVHRR, AATSR, ASMR-E, TMI, in situ Sea ice is based on OSI SAF product

© Crown copyright Met Office Regional ATOVS Retransmission System (RARS) forecast impact Forecast benefit of timely ATOVS data 2 experiments: All ATOVS: data assimilated regardless of arrival time RARS: ATOVS global + fast delivery data from RARS stations NHSH

© Crown copyright Met Office 500 hPa height. RMS difference between analyses with all ATOVS and operationally-available ATOVS ATOVS data missing cut-off would benefit N Pacific and S Hem. Regional ATOVS Retransmission System (RARS) forecast impact

© Crown copyright Met Office European METOP payload Launched Oct 2006 AMSU-A Assimilated January 2007 HIRS/MHS assimilated March 2007 New Sensors IASI ASCAT assimilated Nov 2007 GRAS GOME Under development

© Crown copyright Met Office Polar winds are derived in the overlap region (shown in white) between three successive orbits, by tracking clouds or WV features. Picture from Dave Santek AVHRR polar winds - introduction MODISAVHRR PlatformsTerra, AquaNOAA Metop ChannelIR, WVIR only Available since (NOAA platforms) EUMETSAT plan to produce winds from Metop AVHRR soon. Main disadvantage of AVHRR for wind generation is lack of WV channel.

© Crown copyright Met Office NOAA-18 IRTerra IR Similar quality to MODIS winds (slightly worse at high level in SH). Collocated observations compare well. AVHRR polar winds – comparisons with MODIS

© Crown copyright Met Office Started assimilating NOAA AVHRR winds operationally at the Met Office on 20 May Provides some coverage improvement. AVHRR polar winds – data coverage

© Crown copyright Met Office Impact fairly neutral (as expected when assimilated on top of MODIS polar winds). Main benefit at longer range in extra-tropics. good bad 26 day trial Verification versus analyses AVHRR polar winds – forecast impact

© Crown copyright Met Office MetOp IASI Red – Used (Sea/Land, Clear/MWcloud) Yellow – Used (Sea/Clear only) Blue – Used (1D-Var preprocessor only) Cyan – Rejected Green / Lime – Rejected water vapour channels Channel selection

© Crown copyright Met Office Flight B290 – comparison of observation with LBL simulation and operational O-B statistics for 10-40N

© Crown copyright Met Office Comparison of Met Office and ECMWF profiles for this observation location

© Crown copyright Met Office IASI impact Dec 07 vs Jun 07 June: +1.2 v Obs +0.8 v Anl December: v Obs v Anl December plots “upside down”!

© Crown copyright Met Office 24 May – 24 June 2007 Preferred configuration include water vapour channels obs errors in 4D-Var: 0.5K / 1K / 4K Met Office global NWP index v obs, v analysis +1.0 overall Compare with AIRS for same period v obs, v analysis overall normally see more impact from AIRS MetOp IASI impact trial results

© Crown copyright Met Office IASI Relative to other instruments Verified against observations IASI impact very similar to one AMSU/MHS Compare more channels with coverage in cloudy areas AIRS impact about half of IASI (agrees with other trials) Probably due to observation weighting Cloudy AIRS trial brings impact up to similar level as IASI or AMSU AMSU/MHS and HIRS are MetOp only

© Crown copyright Met Office Cloudy AIRS radiances In current assimilation of AIRS and IASI, cloud-affected obs are rejected only a small proportion of observations retained Moving towards assimilation of cloud- affected radiances simple cloudy RT models allow careful use of channels peaking above cloud Cloud top Weighting functions of channels peaking above cloud

© Crown copyright Met Office Cloudy AIRS radiances Impact of assimilating AIRS in cloudy areas twice as many observations assimilated observations assimilated in meteorologically active areas +1.0 points on Met Office global NWP index equivalent to doubling overall impact of AIRS NWP index change with cloudy AIRS assimilation

© Crown copyright Met Office Trial of new SEAWINDS product The new product results in improved tropical winds, particularly in ocean areas where there is significant rainfall.

© Crown copyright Met Office New SEAWINDS product

© Crown copyright Met Office WindSat wind vectors QuikScatWindSat WindSat-specific quality control developed In particular, low wind speeds rejected due to low information content Ambiguous wind vectors assimilated in similar manner to Quikscat

© Crown copyright Met Office Windsat wind vectors analysis increments and forecast impact QuikScat WindSat relative forecast impact 1-month trial, Aug 2005

© Crown copyright Met Office GPS radio occultation Met Office operational use Sep 2006First assimilation of CHAMP and GRACE-A (GFZ) refractivities Nov 2006 CHAMP and GRACE-A withdrawn – GFZ qc problems May COSMIC satellites assimilated Nov  6 COSMIC satellites Apr 2008 Increase vertical range: 4-27 km  0-40 km Jul 2008Reintroduced CHAMP and GRACE-A Jul 2008Added METOP GRAS

© Crown copyright Met Office Typical coverage during 6 hour period Coverage during a 6 hr cycle

© Crown copyright Met Office COSMIC radio occultation data forecast temperature v sondes S.Hem., Dec 2006, 6 COSMIC v no GPS-RO 24h temperature forecast 200 hPa temperature Mean error RMS error bias rms K 0 42K042K h K

© Crown copyright Met Office Groundbased GPS coverage Observations from E-GVAP near real- time GPS network very high time resolution - often several per hour - potentially useful in 4D-Var At the Met Office: assimilating ZTD into regional (12 km) and UK (4 km) models assimilating one per hour in 4D-Var small positive impacts on cloud, surface temperature, visibility and precipitation operational since March 2007

© Crown copyright Met Office Using IMS data to implement a snow analysis The NESDIS IMS NH snow cover product has been used at the Met Office in combination with snow amount information from the global model background to create a daily snow analysis. Fractional cover on model grid derived from IMS snow cover Presence of snow compared with model first guess Snow removed from or added to model snow field where there is disagreement as to presence of snow Snow amount to add determined using empirical relationship between fractional cover and snow water equivalent S = ( - ln (1 - f c ) ) / D S = snow-water equivalent (1 mm snow-water equivalent ≈ 1 kgm-2 snow areal density) D = masking depth of vegetation fc = fractional snow cover Assimilation trials yield neutral impacts on forecast skill Improvements are seen in analysed snow presence, verified against ground stations Some evidence of improvements in surface/low level T and RH, especially where snow is predominantly removed

© Crown copyright Met Office Snow analysis during assimilation trials

© Crown copyright Met Office 1/12/06 Problems due to IMS data time lag

© Crown copyright Met Office Work in progress….. Add more IASI channels (incl water vapour channels) Assimilation of MSG clear sky radiances and cloud information Extend use of SSMIS to window/wv channels NESDIS snow cover becomes operational Assimilation of WINDSAT winds Longer term…. AMSR-E precipitation Scatterometer soil moisture data assimilated ADM doppler lidar winds preparations underway NPP

© Crown copyright Met Office Questions and answers