30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 11 Observing system experiments using the operational NWP system of JMA with T-PARC 2008 special observations targeted for Typhoon Sinlaku Koji Yamashita*1, Yoichiro Ohta*1, Kiyotomi Sato*1 and Tetsuo Nakazawa*2 1 : Japan Meteorological Agency 2 : Meteorological Research Institute

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 2 Outline Objectives Global Experiments Specification Results of OSEs –Mean Track Forecast Errors –Mean Central Pressure Errors –Case study at 12UTC 11 th September Verification of sensitivity analysis system –Two case studies Trial of OSEs using RS-MTSAT-2-AMV Summary 2

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 33 Objectives Observational data Evaluation To investigate effectiveness of next generation forecast technology, "Interactive forecast system“ To evaluate targeted observational data for typhoon track forecasts using the JMA operational NWP system Observation System Sensitivity Analysis Numerical Prediction Assimilation

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 44 Global Experiments Specification Model –Global Spectral Model ： TL959L60 ( 20km ) (Reduced Gaussian Grid; top 0.1hPa) Assimilation –4D-Var method Forecasts –84 hours for statistical evaluation and longer hours for case studies Target Typhoon ( September, 2008 ) –SINLAKU From 00UTC 09/09/2008 to 18UTC 18/09/2008 –JANGMI From 00UTC 25/09/2008 to 18UTC 30/09/2008 Presentation of Mr. Ohta

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 5 Experimental Design TEST – Special Observations are assimilated ( With Drop ). CNTL – No Special Observations are assimilated ( Without Drop ). BOGUS - TC bogus data are assimilated (with BOGUS : instead of special observation) Utilization of special observations TESTCNTLBOGUS Dropsonde○ (use)×× Special upper sounding(3-hourly) ○×× TC BOGUS × （ no use) ×○

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 6 Typhoon Track and Special Observations Distribution Map ● ： Dropsonde ▲ ： Ship ★： Observatory Before recurvature After recurvature Blue ： Before recurvature （ to 06UTC 14 th Sep. ） Green ： After recurvature （ from 00UTC 16 th Sep. ）

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 7 Results of OSEs (TEST vs CNTL / BOGUS vs CNTL) –Mean Track Forecast Errors –Mean Central Pressure Errors –Case study at 12UTC 11 th September

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 8 Results of OSEs : TEST ～ Mean Track Forecast Error for SINLAKU ～ before-recurvature stage after-recurvature stage significant improvement (95% conf. lev.) 10% Improvement for 66- to 84-hour forecasts 23-30% Improvement for 12-h forecasts TEST CNTL Number of data TEST CNTL

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 9 Results of OSEs : BOGUS ～ Mean Track Forecast Error for SINLAKU ～ before-recurvature stage after-recurvature stage Number of data BOGUS CNTL BOGUS CNTL 10-23% Worse for 6- to 30-h forecasts 15% Improvement for 60- to 72-h forecasts No significant difference

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 10 Results of OSEs : TEST ～ Mean Central Pressure Error for SINLAKU ～ before-recurvature stage after-recurvature stage TEST CNTL TEST CNTL Number of data significant improvement (95% conf. lev.) Over 10hPa reduction of intensity bias for 36-hour forecasts Little significant difference

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 11 Results of OSEs : BOGUS ～ Mean Central Pressure Error for SINLAKU ～ before-recurvature stage after-recurvature stage significant improvement (95% conf. lev.) BOGUS CNTL BOGUS CNTL Number of data Over 10hPa reduction of intensity bias for 24-hour forecasts Slightly stronger intensity bias for 18- to 84-h forecasts

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 12 Case study at 12UTC 11 th September 12 Case study using C-130 aircraft data Typhoon Forecast Track ○ ： using observations × ： using no observations Rapid recurvature and fast moving Test (with Drop): Increased track forecast errors by using all C-130 data Without C-130 (almost same as CNTL): Better track forecasts at the beginning With BOGUS: Better track forecasts at the beginning. Recurvature didn’t occur.

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 13 Why was the worse typhoon track forecast brought for “With Drop”? (m) hPa Difference of average analysis (Z and Wind) at 12UTC 11th September hPa m/s Test ( With Drop ) – Cntl ( Without C-130 ) Deepened Z and strengthened circulation in the south or east side of TC center Moving the typhoon to the south, and next moving to the north-east TC track forecast of Test from FT0 to FT12 FT0 FT6 FT12

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 14 What brought the worse typhoon track forecast ? 14 Dropsonde average wind observations around the center of SINLAKU at 12UTC 11 th September 2008 Assimilated dropsonde observations in the SINLAKU core fields within 200km Different from observed typhoon center Biased and warped vortex to the south Moving the typhoon to the south Next moving to the north-east Probably the worse forecast is caused by assimilating the dropsonde data in the core.

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 15 First Summary Special observations contributed to improve the track and intensity forecasts especially during the before- recurvature stage. The typhoon track errors increased by using special observations. General results for SINLAKU From case Study at 12UTC 11th September It's better not to assimilate dropsonde observations in vicinity of the TC center. TC bogus data instead of special observation were generally efficient to improve the TC track and intensity forecasts.

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 16 Outline Objectives Global Experiments Specification Results of OSEs –Mean Track Forecast Errors –Mean Central Pressure Errors –Case study at 12UTC 11 th September Verification of sensitivity analysis system –Two case studies Trial of OSEs using RS-MTSAT-2-AMV Summary 16

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 17 Verification of sensitivity analysis system First case study of 9/11 from 00 to 12 UTC

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 18 TEST with special observations – 9/11 from 00 to 12 UTC － Init. 00 UTC 10/09/2008 Sensitivity area using SV method at 00 UTC 11/09/2008 (First SV) Case A : Using special observations in the N-E area of typhoon center Case B : Using special observations in the S-W area of typhoon center CNTL : No special observations are assimilated Case A : decreased Case B ： increased Track forecast errors Mean Track Forecast Error

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 19 TEST with special observations of Case A for humidity – 9/11 from 00 to 12 UTC － Init. 00 UTC 10/09/2008 Sensitivity area using SV method at 00 UTC 11/09/2008 (First SV) Targeted area EXP. WindTemperaturehumidity ALL○○○ NOVAPOR ○○× CNTL××× ALL : av. 16% Improvement NOVAPOR : av. 10% Improvement Case A = ALL : av % Improvement

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 20 Why the errors were reduced in Case A ? N N EE Wind Q：NQ：N Q ： NE Q：EQ：E Q：NQ：N Q：EQ：E The mean departure of 3D dropsonde wind and mixing ratio observations from the first-guess (O-B)from the analysis (O-A) Red vector : greater than 10 m/sBlue vector : greater than 5 m/s The analysis was close to the observations. The special observations in the north-east sensitivity area of TC center contributed to reduce the track errors.

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 21 Why the errors increased in Case B? Mean Track Forecast Error Worse forecasts

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 22 Why the errors increased in Case B? Case A Case B CNTL （ no use) O-A in Case B O-B in Case B N N E E W W blue ≧ 5m/s red ≧ 10m/s TC track forecast BST: Observed TC position at JMA The observations were not reflected in the analysis.. The departure of 3D dropsonde wind The number of observations in Case B was much less than in Case A. We are considering the reason.

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 23 Second Summary Verification of sensitivity analysis system Case study of 11 th September –Special observations in high sensitive area in the N-E quadrant of SINLAKU environmental field were effective. –Possibility as the tool of “ Interactive forecast system” The improvement of TC track forecasts was found in the early hour and after FT=60. The humidity observations contributed to improve TC track forecast errors after FT=60. However, they brought almost no impact of forecasts in the early hour. ( All OBS : av. 16% Improvement, without humidity: av. 10% Improvement )

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 24 Second Summary Verification of sensitivity analysis system Case study of 11 th September –Special observations in high sensitive area in the S-W side of SINLAKU environmental field brought worse TC track forecasts. The observations were not fitting to the analysis. The number of observations was much less than in the N-E side of TC center. We are considering the reason..

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 25 Verification of sensitivity analysis system Second case study of 00 UTC 10 th September

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 26 TEST with special observations – 9/10 00 UTC － Area A Area B Special Observations Init. 00 UTC 09/09/2008 Sensitivity area using SV method at 00 UTC 10/09/2008 (First SV) Exp. SP.OBS: Area A SP.OBS: Area B Result of forecasts NODATA××CNTL ALL(A+B)○○ Neutral Area A○×Worse Area B×○Better

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 27 Cause of result in case of 00 UTC 10 September Area A NO DATA Area B ALL(A+B) TC track forecast BST: Observed TC position at JMA Modification of circulation in the N-E area of TC center ( Area A ) O-B in ALL O-A in ALL blue ≧ 5m/s red ≧ 10m/s Moving the typhoon to the northward especially in Area A N E W N E W S S Better

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 28 Third Summary Verification of sensitivity analysis system Case study of 10 th September –Special observations in high sensitive area in the N-E side of TC were not effective. –Special observations in low sensitive area in the S-W side of TC were effective. Modifying of counterclockwise circulation in the N-E area of TC center, and moving the typhoon to the northward

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 29 Trial of OSEs using RS-MTSAT-2-AMV at 18 UTC 17 th September

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 30 Experimental Design ( TEST and CNTL) Same as global experiments specification for special observations –TL959L60 ( 20km ), 4D-Var method Without the TC bogus data and special observations Usage of two kinds of MTSAT-2 rapid scan AMV ( only TEST ) –Cloud images of the intervals of 4 or 7 minutes All winds are thinned by 1°in horizontal and 100 hPa in vertical. A minimum horizontal distance is 100km. Only one wind selected per box in the hourly time window Added to other AMVs of satellite data –The intervals of 15 minutes ( same as usage of the others GS wind ) All winds are thinned by 2°in horizontal and 100 hPa in vertical. A minimum horizontal distance is 200km. Only one wind selected per box in the 6 hour time window Other AMVs are assimilated together.

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 31 Example of AMV after QC at 18 ～ 19UTC 11 th September ≒ 100 km thinning Others 200 km thinning Red color ≦ 400hPa level Blue color ≧ 850hPa level

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 32 Result of OSE Slightly improvement of slow bias speed for TC track forecasts Track Forecast Error Possibility of improvement for TC track forecasts using RS-MTSAT-2-AMV data

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 33 Thank you for your attention 33

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 34

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique TC bogus ( Outline ) 35 Tropical Cyclone generated on the Northwest Pacific ocean Wind speed is greater than 28 knots. Setup Horizontal Psea Wind except TC center Four bogus data are located every 200 km from TC center. Vertical Wind except TC center Located on the standard isobaric surface (1000,925,850, 700,500,400 and 300 hPa )

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 36 Case study at 12UTC 11 th September 36 Case study using C-130 aircraft data Typhoon Forecast Track Increased track forecast errors by using all C-130 data Better track forecasts at the beginning ○ ： using observations × ： using no observations Sensitive in the TC center core fields

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 37 Core SINLAKU environmental field 11Z 13Z 12Z 14Z C-130 targeted observation data and observed time TC center

30 November December International Workshop on Advancement of Typhoon Track Forecast Technique 38