Observing System Experiments using a singular vector method for 2004 DOTSTAR cases

Transcription

1 Observing System Experiments using a singular vector method for 2004 DOTSTAR cases Korea-Japan-China Second Joint Conference on Meteorology 11 OCT Munehiko YAMAGUCHI 1 Takeshi IRIGUCHI 1 Tetsuo NAKAZAWA 2 1: Numerical Prediction Division, Japan Meteorological Agency 2: Typhoon Research Department, Meteorological Research Institute

2 THORPEX contributes to the developing of an interactive forecast system current system observation data assimilation forecast user interactive forecast system data observation assimilation targeting observation sensitive analysis forecast user A sensitive analysis technique is needed to maximize the effect on a numerical prediction and to minimize the cost of the observation. Vaisala targeting observation sensitive area JAXA NASA Strategies for targeting observation ensemble forecasting singular vector (SV) method ETKF Global trend A Comparison of Adaptive Observing Guidance for Atlantic Tropical Cyclones S. J. Majumdar, S. D. Aberson, C. H. Bishop, R. Buizza, M. S. Peng, and C. A. Reynolds Mon. Wea. Rev., 134,

3 Singular vector method at JMA A singular vector method is developed at JMA to make initial conditions in both ensemble prediction systems, the medium-range EPS and the typhoon EPS, which is planned to be newly operational in The linearized model and its adjoint version are derived from the global 4D-Var analysis system. They consist of full dynamics based on Eulerian integrations and full physical processes containing representations of vertical diffusion, gravity wave drag, large-scale condensation, long-wave radiation and deep cumulus convection. The resolution of the linearized model is T63L40. The norm for a SV calculation is based on a total energy norm (Barkmeijer 2001). Tr = 300K, Pr = 800hPa Cp: specific heat of dry air at constant pressure Lc: latent heat of condensation Rd: gas constant for dry air wq is set to 0 above about 500hPa vertical integration is limited under about 300hPa wt and wq are decided as follows wt wq Initial norm Final norm Wind and specific humidity component are dominant in a calculated singular vector.

4 Evaluate a SV method as a strategy for Targeting Observation JMA has executed Observing System Experiments (OSEs) to investigate the usefulness of the singular vector method as a strategy for sensitive analysis. For the initial time of 12UTC 08 June 2004 when totally 16 dropsondes were dropped into typhoon CONSON by the DOTSTAR (Dropsonde Observation for Typhoon Surveillance near the Taiwan Region) project, 4 predictions with JMA Global Spectral Model (TL319L40) about the use of the dropsondes in the global 4D-Var analysis are executed. (I) all dropsonde observations are assimilated (II) no dropsonde observations are assimilated (III) Three dropsonde observations within a sensitive region are assimilated (4, 9, 12) (IV) Six dropsonde observations outside the sensitive region are assimilated (6, 8, 10, 13, 15, 16) Sensitive analysis result x CONSON s center position Sensitive region shows vertically accumulated total energy by the 1st moist singular vector. Targeted area for the SV calculation is 25N-30N, 120E-130E. Optimization time interval is 24 hours.

5 OSEs result on CONSON s track forecast Red: (I) all dropsonde obs Blue: (II) no dropsonde obs Green: (III) Three dropsonde obs within the sensitive region Light blue: (IV) Six dropsonde obs outside the sensitive region (III) (I) (IV) similar (II) is almost same with (IV)

6 Typhoon MELOR s (T0319) case DOTSTAR for MALOR at UTC MELOR s center position TRMM image (rainrate (mm/hr)) 1 st SV at 700hPa (wind & specific humidity) OSE for MALOR MELOR s best track Track forecast using the 1 st SV MELOR s northeast movement is not expressed although all dropsonde data is used in making an initial condition. g/kg SV method could have suggested the eastward area against Taiwan as a sensitive region. m/s

7 Probabilistic Forecast for severe weather using Typhoon EPS Observed Precipitation (mm) from UTC to UTC Observed Precipitation (mm/hr) at Irozaki UTC UTC UTC High resolution GSM (20km) Initial time 0612UTC Control run Initial time 0700UTC Perturbed run (03p)

8 Contribution toward T-PARC JMA has resolved to provide the sensitive analysis products by the singular vector method on real-time base. The data will be opened to the THORPEX Community in Asia on an internet homepage which needs user authentication. top page click The first column is the singular vector number. The second column shows the typhoon track forecasts using the singular vector as the initial perturbation (red line is control run, green is positively perturbed run and blue is negatively perturbed run). The third column shows the sensitive analysis result which is expected to indicate where to observe. The fourth and fifth column show the vertical and spectrum structure of the singular vector.

9 Summary JMA has demonstrated the feasibility of a singular vector method as a strategy for sensitive analysis targeting TCs by performing Observing System Experiments. JMA opens the real-time sensitive analysis results through the Internet to realize an interactive forecast system and to contribute to T- PARC in Thank you for listening