Report to 24 th NAEDEX Meeting Roger Saunders

Report to 24 th NAEDEX Meeting Roger Saunders + many others, Met Office, Exeter © Crown copyright Met Office

Operational NWP Models: July 2012 Global Ø 25 km 70 L ØHybrid 4 DVAR – 60 km inner loop Ø 60 h forecast twice/day Ø 144 h forecast twice/day Ø+12 member EPS at 60 km 4 x/day NAE Ø 12 km 70 L Ø 4 DVAR – 36 km inner loop Ø 60 h forecast Ø 4 times per day Ø +12 member EPS at 18 km 4 x/day UK-V (& UK-4) Ø 1. 5 km 70 L Ø 3 DVAR (3 hourly) © Crown Ø 36 h forecast copyright Met Office Ø 4 © Crown copyright Met Office Global Regional Ensemble Prediction System = MOGREPS times per day

Operational NWP Configuration: 2013 -2014 Global Ø 16 -20 km 70 L (80 km top) ØHybrid 4 DVAR (40 km inner-loop) Ø 60 hour forecast twice/day Ø 144 hour forecast twice/day Ø 44/12 member 33 km MOGREPS-G 4*/day UKV Ø 1. 5 km 70 L (40 km top) Ø 3 DVAR (hourly) Ø 36 hour forecast, 4 times per day Ø 12 member 2. 2 km MOGREPS-UK © Crown copyright Met Office

Current status September 2012 • 4 D-Var hybrid data assimilation system • Assimilating the following satellite observations: © Crown copyright Met Office

Current status II September 2012 Additionally (not shown): • • • © Crown copyright Met Office GOES radiances Soil Moisture (ASCAT) Cloud height/amount (SEVIRI) SSTs (OSTIA – AVHRR, MODIS, SEVIRI, . . ) Sea ice (OSI-SAF) Snow cover (NESDIS)

How we get the data Washington RMDCN Local US data Globalreception Global Networks EUMETCAST © Crown copyright Met Office

Monitoring RARS stations Networks: © Crown copyright Met Office EARS Asia Pacific RARS South American RARS

Recent changes to usage of data and model • 20 July 2011: Assimilate GOES clear sky radiances and more lower peaking IASI radiances over land • 20 July 2011: Assimilate hourly METAR data • 28 March 2012: Assimilate total column GPS in global model • Aircraft ADS/AIREP reports over Atlantic patchy this Spring • Started to assimilate Canadian wind profilers (8 out of 9 available) • Reduction in US wind profilers now only assimilating 14 out of original 33 • Assimilated many US dropsondes around TCs • 17 September 2012: Migrate from IBM Power-6 to Power 7 © Crown copyright Met Office

Satellite sensors used for NWP © Crown copyright Met Office

Satellite data volume into Met Office © Crown copyright Met Office

Observations assimilated – Sep 2012 Observation group Observation Sub-group Items used Daily extracted % used in assimilation Ground-based vertical profiles TEMP T, V, RH processed to model layer average As TEMP, but V only 1, 350 95, 77 850 11, 500 22 30 PILOT PROFILER Satellite-based vertical profiles METOP-A NOAA-15/16/18/19, Aqua AIRS, IASI, HIRS, AMSU-A/B, MHS Radio-occultation COSMIC, GRAS Radiances directly assimilated with channel selection dependent on surface instrument and cloudiness. Profiles of refractive index ATOVS: 3, 000 IASI: 324, 00 AIRS: 324, 000 COSMIC: 1600 GRAS: 600 CHAMP+Grace: 400 5 4 4 60 70 65 Aircraft Manual AIREPS (including ADS) Automated AMDARS TAMDAR T, V as reported with duplicate checking and blacklist 11, 000 76, 74 290, 000 50, 000 24, 24 0, 0 Satellite atmospheric motion vectors GOES 13, 15 BUFR Meteosat 7, 9 BUFR MTSAT BUFR Terra/Aqua MODIS AVHRR polar AMVs IR, WV IR, VIS, WV IR, WV, clear sky WV IR 170000 540000 80000 170000 25000 5 3 6 3 4 Satellite-based surface winds METOP ASCAT (+ soil moisture) CORIOLIS WINDSAT OSCAT (soon) KNMI retrievals NRL winds 1, 000 1, 600, 000 10 1 Ground-based surface Land SYNOP Pressure (processed to model surface), V, T, RH P, V, T P, T, RH P, V, T, RH 80, 000 84, 81, 89 6, 500 7, 500 14, 000 5, 500 135, 000 81, 78, 63 77, 80, 78 90, 4 20, 14, 15 35, 30, 32 SHIP Fixed Buoy Drifting BUOY © Crown copyright Met. Mobile SYNOPs Office METARs

Satellite data delays ATOVS NOAA-19 METOP © Crown copyright Met Office

Satellite data delays ATOVS NOAA-17 NOAA-18 © Crown copyright Met Office

ATMS trials Channel 12 raw O-B Bias corrected Striping Strong regional bias • We plan to get ATMS into operations in March 2013 with: • Footprint matching AMSU and noise reduction • Channels 6 -15, 18 -22 • QC following treatment of AMSU © Crown copyright Met Office

Cr. IS data AIRS 172 O-B IASI 222 O-B Cr. IS 88 O-B • Planned implementation: • Similar to AIRS/IASI • Use 129 channels - 72 T, 44 WV, 13 Surface, 0 SW (band 3) © Crown copyright Met Office

Satellite data delays (AMVs) © Crown copyright Met Office

Monitoring of GOES AMVs Slow bias when changed from GOES-11 to GOES-15 but recovered © Crown copyright Met Office

AMV thinning strategy Main approach to alleviate problems with spatially and temporally correlated error (another option is superobbing). Current strategy: All geo winds thinned in 2°x 100 h. Pa boxes. All polar winds thinned in 200 x 200 km x 100 h. Pa boxes. Main limitation (legacy of 3 D VAR) Wind selected by lowest error for geo Wind selected by closest to centre of box for polar winds. Only one wind selected per box in the 6 hour time window. New Approach: Introduce 2 -hourly temporal thinning -> 3 x number of AMVs used Make better use of hourly data available from MSG, MTSAT and GOES-13/15 (available in test mode) © Crown copyright Met Office Operational 2 -hourly thinning

AMV thinning strategy Large impact on 250 h. Pa mean wind analysis – tropics and MSG jet regions Headline NWP index scores: Season Index Obs UK Anl EC Anl 14/12/11 – 14/01/12 Old +0. 48 -1. 73 +1. 6 New +0. 9 +0. 1 Old +0. 48 -1. 3 New +0. 4 -0. 1 04/06/12 – 03/07/12 • Significant positive impact versus observations ~ +0. 5 (typical AMV impact is just over 1 point). Overall fit to observations is improved, particularly for wind obs, with small but consistent better fit to aircraft and sondes. • Verifying against own analysis gives large negative impact - largely from short range T+24. Poor scores likely due to changes made to the character of the verifying analyses (throwing lot more data in), rather than a degradation of forecast quality. • Verifying against ECMWF analyses gives a large positive impact - suggests that by fitting closer to the AMVs we are moving closer to an ECMWF solution © Crown copyright Met Office

Future Short term • Assess hourly GOES AMVs – currently being generated at NOAA on a routine, but experimental basis – and test with new thinning strategy • Helping coordinate a new NWP winds impact study as part of the IWWG – see https: //groups. ssec. wisc. edu/groups/iwwg/activities/nwp-winds-impact-study Also • AMV height error estimates and improved tracking from GOES-R algorithm developments © Crown copyright Met Office

Oceansat-2 Assimilation of OSCAT wind vectors from Indian Oceansat-2 satellite. OSCAT: Ku-band, conical scanning pencil-beam scatterometer operating at 13. 52 GHz, similar in design to the Quik. SCAT instrument which failed in November 2009. Became TS Joyce TS Isaac Utilising the 50 -km L 2 B wind product produced by KNMI/OSI-SAF (http: //www. knmi. nl/scatterometer) Improved global coverage of ocean surface wind vectors alongside ASCAT on Metop-A and Wind. Sat. Wind retrieval results in ambiguous set of 2 -4 wind solutions. © Crown copyright Met Office

Oceansat-2 All data After QC Assimilation procedure: • Observations screened for land, sea ice and rain contamination • Wind speed bias correction • Assign prior probabilities • Assimilated as ambiguous wind components in 4 D VAR with variational QC Addition of OSCAT shows a similar positive impact (~ +0. 3 points on NWP index) to what we used to see for Quik. SCAT when added on top of ASCAT Also see an improved fit of ASCAT and Wind. Sat to analysis and background forecast winds, e. g. 2% reduction in O-B V-component RMS in tropics © Crown copyright Met Office

GPSRO – assimilation of C/NOFS bending angle data • C/NOFS is a US military satellite – data is processed by UCAR. • It has an orbital inclination of 13° so useful for tropics • Data currently unavailable below ~8 km. • Timeliness issues mean that much of the data won’t be assimilated. Tropics had few occultations before C/NOFS. © Crown copyright Met Office C/NOFS Bending angle O-Bs. Similar ‘bias’ to other satellites at these latitudes.

Timeliness for C/NOFS © Crown copyright Met Office

Ground-based GNSS Current Zenith Total Delay observation availability © Crown copyright Met Office egvap. dmi. dk

Ground-based GNSS Observations Sensitivity Experiment Jan-Mar 2012 © Crown copyright Met Office Image courtesy of Richard Marriott

Ground-based GNSS • July-August 2012 • Addition of global network outside Europe, and increased Obs error • Verification against obs • 0. 377 increase in NWP index © Crown copyright Met Office

Dust AOD Observations MSGAOD(¹) SATAOD Platform Geostationary (MSG) Polar (Aqua) Coverage 60 W: 60 E, 60 S: 60 N Global Frequency Hourly (<70° SZA) Daily (sunlit period only) AOD retrieval IR-based (over land) MODIS Deep. Blue/Land(²) Obs Error 0. 37(3) 0. 22(4) In Met. DB Since Sep-2009 Since Oct-2011 1. Pradhan & Saunders (2009) 2. LANCE MODIS 3. Brindley & Russell (2009) 4. Salustro et al. (2010)

Dust AOD Observation - Obs over land only (covers the source regions) - MODIS land AOD (dust type) and Deep. Blue AOD (all) - No bias correction at QC level

Mineral dust AOD forecast § The mean differences show addition of dust, but it looks better than before (e. g. , 19 -Dec dust storm in Afghanistan) § Clear benefits from inclusion of MODIS AOD over central and eastern Asia.

Observation impact in Met Office global NWP space-based = 64%; surface-based = 36%

Satellite observation impact per platform

Future Work • Assimilate data from more satellites: • Met. Op-B, Suomi-NPP, FY-3, ADM • MSG-3, MTSAT (rads), FY-2 (AMVs) • • • Improved assimilation of cloud retrievals Improved assimilation of radiances over land Improved treatment of variable O 3 & CO 2 More complete use of hyperspectral IR radiances Operational assimilation of aerosol optical depth Variational bias correction © Crown copyright Met Office

Questions and answers © Crown copyright Met Office