Jaekwan Shim, Yoon-Jeong Hwang, Yeon-Hee Kim, Kwan-Young Chung Forecast Research Division, National Institute of Meteorological Research, KMA The Experiments of Sensitivity test with 2012 winter special observation data using WRF model 2012 THORPEX-Asia Workshop

Page  2 Background West Sea Observation points of Central area Observation points of east coast line Observation targets Observe the weather elements using KMA ground-based observation network Observe the weather elements over the sea using Gisang1 Observe the precipitation and cloud vertical structure using Radio-sonde and wind-profiler, Radiometeor The special observation has performed for two years around middle area in south Korea  Expectation of bservation effects − initial condition Improve the initial field by assimilation scheme using obs data − cycle run Reduce the forecast error (first guess) by adding observation data continuously − location Verify the optimal locations of Observation that are sensitive to the predictibility

Page  3 INC BOSBOSINC CNTL Looks like Similar initial conditions for each observation It can make differences in 48-h forecasts! Background 00 fcst 48fcst

Page  4 Objective  Sensitivity Analysis − Evaluating how observation data affects a forecast − Location for which additional observations may reduce errors or improve the forecast evaluate the initial increments translated downstream investigation of observation location are sensitive to the forecast the precipitation forecast is investigated.

Page  5 Cases  The selected case is the developing cyclone while passing the West sea and Korean peninsula  the cold front was formed over the south korea on 31 January The relatively plenty of snow fall is recorded along cold front.  The stream line and moisture flux flowed in Korean peninsula between the Siberia high and north Pacific high at least for 24 hours. 1200UTC 31 JAN 2012

Page  6  Experiment design(I) Forecast model WRF/ARW 3.1 Resolution12 km (141 x 161) Forecast time72hours Initial & boundary conditionUM forecast field Physical Process Microphysics scheme WSM6 Radiation scheme Dudhia/RRTM Cumulus parameterization Kain-Fritsch Land-surface model Noah LSM PBL scheme YSU Scheme Data Assimilation system WRFDA v3.1.1 Method3DVAR Resolution 12 km ( 141x161) Assimilation window4 hours (±2) casesRemarks 19 JAN 2012 snow east-south coast 31 JAN 2012 Snow Over the Korean peninsula 25 FEB 2012 Snow East coast and southwest land 3 march 2012 rain Over the Korean peninsula Experiments period ~2.1

Page  7 3DVAR data assimilation UTC CYCLE run 72-h forecast 3036 ExperimentsRemarks CNTLOperational observation data (GTS) INCCNTL + Incheon OBS BOSCNTL + Boseong OBS BOSINCCNTL + Incheon + Boseong  Experiment design (II)

Page  8 Increments (A-B) on 0600UTC 26 JAN 2012 INC BOSBOSINC CNTL Increments (A-B) on 1200UTC 26 JAN 2012 Sensitivity Experiment : Results

Page  9 Increments (A-B) on 1200UTC 30 JAN 2012 Increments (A-B) on 1200UTC 31 JAN 2012 INC BOSBOSINC CNTL Sensitivity Experiment : Results

Page  10 CNTL AWS Difference (experiments-CNTL) 12 hr accumulated precipitation and difference (1200UTC 31 JAN 2012) BOS INC BOSINC TMPA Sensitivity Experiment : Results

Page  11 Difference of 850 hPa Mixing ratio (exp-ctl) on 0600 UTC 31 JAN 2012 at 12hr fcst Difference of 850 hPa Mixing ratio (exp-ctl) on 0600 UTC 31 JAN 2012 at initial Sensitivity Experiment : Results Exps - CTN

Page  12 F00 F12 F24 BOS INC BOSINC Sensitivity Experiment : Results Increments of 850 relative humidity 850 wind vectors

Page  13 Increments of 500 height from -6 to equivalent potential Temperature BOS INC BOSINC Sensitivity Experiment : Results F00 F12 F24

Page  14 Exp.BOSINCBOS+INC rate (2.5 mm) 34%1%27% 2.5mm/12hr ETS ( ~ ) 12hr ETS ( ) Sensitivity Experiment : Results ETS for 12 hours accumulated prec. On 31 January 2012

Page  15 Geopotential height Temperature At low altitude, RMSE of height of all experiments show small difference. Otherwise, CNTL and INC have the largest RMSE than BOS and BOSINC at upper altitude. RMSE of temperature is similar with RMSE of height except for low levels. The observation data of Boseong reduced the RMSE in this case. RMSE of height and Temperature Sensitivity Experiment : Results

observation data is used to identify sensitivity regions of winter 2012 over south Korea. Sensitivity test is conducted using two points of observation data initial increments in experiments were introduced near the observing points. These increments damped as they translated downstream. Predictability of BOS and BOSINC are better than INC and CNTL(noDA). The moisture adjustment contribute the improvement of predictability To improve predictability of south Korea, observation of the south is important in land. If supplementary observation is needed, it must be conducted over the south of the Korean Peninsula. Summary and Conclusion