UM 4 DVar Regional Reanalysis Progress Richard Renshaw

UM 4 D-Var Regional Reanalysis Progress Richard Renshaw, Stephen Oxley, Adam Maycock, Peter Jermey, Dale Barker, Ding. Min Li © Crown copyright Met Office

Contents Progress with technical work First attempt at reanalysis Developments for 2012/13 © Crown copyright Met Office

WP 2. 1 Building capacity for advanced regional data assimilation Set up and demonstrate an advanced regional reanalysis system Based on operational North Atlantic/Europe LAM Planning to analyse 2010 & 2011 © Crown copyright Met Office

Met. O Regional Reanalysis: Horizontal Domain 12 km grid 480 x 384 © Crown copyright Met Office

Technical work Build a reanalysis system • to run at ECMWF • taking observations, start file, boundary conditions from ECMWF archives • storing analyses in ECMWF archives • and producing data to validate the reanalysis. © Crown copyright Met Office

ECMWF “interface” Met Office Running at ECMWF © Crown copyright Met Office

Technical Highlights • Set up Met Office systems on ECMWF IBM • Use observations from mars (ECMWF BUFR format) • Preprocess satellite radiances • reconstruct level 1 b files from BUFR data • convert level 1 b counts to level 1 c radiances (AAPP) • map between instrument grids (e. g. AMSU+MHS to IASI) • Convert and map ERA-Interim GRIB files to UM file format, for start files and boundary conditions • Use ‘CYLC’ to develop and run a reanalysis suite © Crown copyright Met Office

CYLC: Scheduling System CYLC, written by Hilary Oliver (NIWA) http: //hjoliver. github. com/cylc/ + ROSE – adds interfaces and configuration management © Crown copyright Met Office

Why CYLC ? • • • Will replace ageing Met Office system Can build, run, monitor suites of any complexity Portable – Open source Flexible Intelligent job scheduling - define dependencies for each task - tasks will run early if possible © Crown copyright Met Office

sample CYLC suite © Crown copyright Met Office

Dale’s challenge Regional reanalysis - why bother ? ? ! © Crown copyright Met Office

Evidence from operational NWP 25 km Global vs 12 km NAE © Crown copyright Met Office

. . . the benefits of resolution global 25 km NAE 12 km screen temperature rms error (K) forecast range © Crown copyright Met Office

. . . and the disadvantage of boundaries! NAE global mean sea level pressure rms error (Pa) forecast range © Crown copyright Met Office

ERA-Interim vs 12 km EURO 4 M • • T 255 (80 km), 60 levels T 159 (125 km) 4 D-Var 12 -hour analysis window assimilate: • conventional obs • satellite radiances • • 12 km, 70 levels 36 km 4 D-Var 6 -hour analysis window assimilate: • • • conventional obs incl vis satellite radiances Ground-based GPS Cloud Precipitation • Initial state and boundary conditions from ERAInterim analyses © Crown copyright Met Office

model orography ERA-Interim Model T 255 (80 km) Var T 159 (125 km) Met Office Model 12 km Var 36 km © Crown copyright Met Office

First attempt at reanalysis. . . May 2010 • Floods in Poland, eastern Europe June 2010 • Severe storms France/Spain July 2010 • Russian heatwave spreading West, forest fires © Crown copyright Met Office

Poland floods, 16 th May 2010 e-obs gridded 24 hr rainfall © Crown copyright Met Office http: //eca. knmi. nl/

Poland floods, 16 th May 2010 radar 24 hr rainfall Czech Hydrometeorological Institute © Crown copyright Met Office

Poland floods, 16 th May 2010 e-obs 12 km reanalysis © Crown copyright Met Office

Poland floods, 16 th May 2010 e-obs ERA-Interim © Crown copyright Met Office

Russian heatwave, July 2010 e-obs Tmax, 10 -07 -2010 © Crown copyright Met Office

ERA-Interim obs 12 km EURO 4 M Tmax 10 -07 -10 © Crown copyright Met Office

Verification vs Radiosonde Temperature rms error T+0 T+6 ERA-Interim EURO 4 M 12 km © Crown copyright Met Office

Verification vs Radiosonde Vector wind rms error T+0 T+6 ERA-Interim EURO 4 M 12 km © Crown copyright Met Office

Developments for 2012/13 • Variational bias correction • ODB – obs monitoring • Extend observations dataset • Cloud and Precipitation assimilation • Validation – extreme statistics • Collaborate on cross-validation © Crown copyright Met Office

Variational Bias Correction Airmass-dependent bias correction of satellite radiances (based on Harris and Kelly, 2001) Currently coeffs c are calculated off-line monthly Var. BC will give smooth and automatic updating Work is underway – finish in 2012 © Crown copyright Met Office (Ding. Min Li, Dale Barker, Andrew Lorenc)

ODB – obs monitoring database • Established ECMWF database + utilities • Array of tools available “for free” • Metview macros (quick look) • Obstat (detailed stats / graphics) • Replaces several diverse monitoring tools at MO • Joint development • Currently ~1. 5 years into 3 year joint funded post at ECMWF (Peter Kuchta) • Setting up Obstat at MO • Other NMSs already using ODB (CAWCR, KMA) © Crown copyright Met Office

Extend observations dataset • Work with UEA (WP 2. 5) to extend surface and sonde datasets • Seeking sub-daily raingauge data. . . © Crown copyright Met Office

Cloud + Precip assimilation • Operational UK models assimilate cloud products (satellite) and rainfall (radar, latent heat nudging) • For EURO 4 M, plan to assimilate cloud reports and raingauge accumulations from surface stations • Needs development work (2012/13): • • • source sub-daily raingauge accumulations decode and interpret surface reports (Peter Francis) quality control assimilate rainfall accumulations in 4 D-Var reduce effect that analysis increments trigger rain in model © Crown copyright Met Office

Validation - Extremes • High impact weather • Should show a benefit for regional reanalysis • Focus on: • precipitation • temperature • winds • Need to look at probability distributions (pdf’s), e. g. • number of values outside 10 th/90 th percentile • count consecutive days with high/low values • accumulated precipitation over several days © Crown copyright Met Office

Collaboration – Cross-Validation Compare our reanalysis against: • SMHI • ERA • Obs climatologies • Others ? © Crown copyright Met Office

Summary • Reanalysis system ready to run • Already better than ERA-Interim in some features, but not all (yet!) • Science development and testing this year © Crown copyright Met Office

Questions ? With thanks to: Tom Green, Nigel Atkinson, Sreerekha Tr, others. . . © Crown copyright Met Office

Extra slides. . . © Crown copyright Met Office

First attempt at reanalysis. . . May 2010 June 2010 July 2010 © Crown copyright Met Office • 3 x 1 month runs, with overlap

How long to spin up ? rms surface pressure © Crown copyright Met Office

How long to spin up ? rms screen temperature © Crown copyright Met Office

Impact of Var resolution 12 km 4 D-Var © Crown copyright Met Office 100 km 4 D-Var

Verification vs Radiosonde Relative Humidity rms error T+0 T+6 ERA-Interim EURO 4 M 12 km © Crown copyright Met Office

Global ODB trial output NH Surface T mean (o-b) © Crown copyright Met Office