GPC-Seoul: Status and future plans WMO CBS ET-OPSLS, Exeter, UK, 10-14 March 2014 GPC-Seoul: Status and future plans Suhee Park Korea Meteorological Administration

Contents Current seasonal forecasting system and products New seasonal forecasting system: GloSea5 Description of GloSea5 General features of operational system Results of hindcast and forecast Summary and future plans

Current seasonal forecasting system & products The operational LRF system of GPC-Seoul is a 2-tier system. GPC-Seoul provides forecasts of 6 variables to WMO LC-LRFMME and verification results to WMO LC-LRFSVS. Global SST Prediction Model LRF Global Dynamic model Initial Condition monthly : OISST, UV850, UV200, T850,Z500, SLP, Prcp. 6 hourly : U, V, T, GPH, Psfc, MSLP, RH El-Nino Prediction Model CPPM(Coupled Pattern Projection Model) LLRM(Lagged Linear Regression Model) Persistence Model GDPAS(GCM T106L21) 230 day forecast Ensemble size : 20 members (fcst&hcst) Hindcast period : 1979-2012 Boundary Condition Nino 3.4 Index Global SST forecast Monthly forecast : T, GPH, RH, Precip., MSLP, U, V Verification : T2m, Z500, Z850, MSLP, Precip.  2m surface air temperature  Precipitation  Mean sea level pressure  850hPa temperature  500hPa geopotential height  Sea surface temperature

New seasonal forecasting system: Joint system June 2010, the collaboration agreement was made between KMA and UK Met Office for a joint seasonal forecasting system. To establish a joint seasonal forecasting system with the joint aim of developing and providing operational seasonal forecasting products. Joint System Products sharing Joint products KMA product UKMO product Major advantages are to share ensemble members as many as possible. The Joint system will be launched by December 2014.

ORCA tri-polar grid at 0.25° Joint seasonal forecasting system : GloSea5 Joint system, GlosSea5, is the fifth version of the Met Office ensemble prediction system for seasonal forecasting, which has been built based on the latest version of HadGEM3. UM (Atmosphere) NEMO-CICE (Ocean & Sea Ice) OASIS3 (coupler) Atmosphere Ocean & Sea Ice Model UM (UM 8.0) NEMO-CICE (NEMO 3.2, CICE 4.1) Horizontal resolution N216 (0.83° x 0.56°) ORCA tri-polar grid at 0.25° Vertical resolution 85 levels (~85km) 75 levels UM (Met Office Unified Model) for Atmosphere JULES (Joint UK Land Environment Simulator) for Land Surface NEMO (Nucleus for European Modeling of the Ocean) for Ocean CICE (Los Alamos National Laboratory) for Sea-ice OASIS (CERFACS) for coupling between component models

GloSea5: Initialization of the system Forecast (initialized daily): - Atmosphere & land surf: KMA NWP analysis (4d-Var) UKMO system uses Met Office NWP analysis! - Ocean & sea-ice: Met Office NEMOVAR analysis (3d- Var joint system for ocean, med-range, monthly and seasonal) Hindcast (initialized weekly): - Atmosphere & land surf: ERA-Interim reanalysis - Ocean & sea-ice: Seasonal ODA reanalysis - Fixed start dates of 1st, 9th, 17th, 25th of each month - Hindcast period : 14 years (1996-2009) Period will be extended for 25 years (1989-2013)

GloSea5: Generation of ensemble member Seasonal Forecast: - 2 members run each day. - Seasonal forecast updated monthly by pulling together last 3 weeks (i.e. 42 members) Monthly Forecast: - 2 additional members run each day. - Monthly Forecast updated weekly by pulling together last 7 days (i.e. 28 members) Hindcast (for monthly-seasonal): - 3 members run each week in real time (14 years per member) - Hindcast for seasonal forecast updated monthly by pulling together last 4 weeks (i.e. 12 members) Hindcast for measonal forecast updated monthly by pulling together last 2 weeks (i.e. 6 members)

Hindcast result : GPC-Seoul vs GPC-Exeter Bias and correlation of 500hPa geopotential height KMA UKMO Bias Corr

Forecast result : GPC-Seoul vs GPC-Exeter Mean and anomaly of 500hPa geopotential height KMA Observation UKMO

Summary KMA and UKMO are trying to establish a joint seasonal forecasting system (GloSea5) with the joint aim of developing and providing operational seasonal forecasting products. Although both GPC-Seoul and GPC-Exeter are using same forecasting model, they use different initial conditions (ICs) for the atmospheric and land surface model. Also, a forecasting model utilize a stochastic physics. Different ICs and a stochastic physics lead to the significant regional-scale diversity in products between GPC-Exeter and GPC-Seoul.

Future plans From June 2014 the operational forecast model of KMA will be replaced by the GloSea5, a join seasonal forecasting system with Met Office. All products of KMA will be provided with GloSea5 to WMO LC-LRFMME for LRF, ECMWF for S2S.

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