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Eric A. Hendricks 1 Melinda S. Peng 1 Tim Li 2 Xuyang Ge 3

Initialization Schemes in the Naval Research Laboratory’s Tropical Cyclone Prediction Model (COAMPS-TC). Eric A. Hendricks 1 Melinda S. Peng 1 Tim Li 2 Xuyang Ge 3 1 Naval Research Laboratory (NRL), Monterey, CA, USA 2 University of Hawaii and IRPC, Honolulu, HI

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Eric A. Hendricks 1 Melinda S. Peng 1 Tim Li 2 Xuyang Ge 3

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  1. Initialization Schemes in the Naval Research Laboratory’s Tropical Cyclone Prediction Model (COAMPS-TC) Eric A. Hendricks1 Melinda S. Peng1 Tim Li2 XuyangGe3 1Naval Research Laboratory (NRL), Monterey, CA, USA 2University of Hawaii and IRPC, Honolulu, HI 3Pennsylvania State University, State College, PA USA Acknowledgements: Jim Doyle (NRL), Rich Hodur (SAIC), COAMPS-TC group CMOS 2012 Congress / AMS 21st NWP and 25th WAF Conferences Montreal, Canada, 29 May-1 June 2012

  2. Introduction • A crucial part of TC intensity predictions is an accurate and balanced TC vortex initially • 3DVAR data assimilation systems usually lack proper balance constraints suitable for multi-scale TC; rapid adjustment often occurs after initialization • A 4D data assimilation system would alleviate the initial imbalance problem to some degree • Lack of observational data for TC intensity and structure remains What do we do in the mean time? Hybrid 3DVAR/Dynamic Initialization Schemes have the possibility of improving the initial balance and storm intensity/structure, while allowing model physics spin-up, potentially leading to improved intensity and track forecasts

  3. Dynamic Initialization Schemes: TCDI, DI, TCDI/DIApplication to TC Prediction Using COAMPS-TC NOGAPS/NCEP analysis Cold Start TCDI: Hendricks et al. (2011) WAF, Zhang et al. (2012) WAF 3DVAR data assimilation Remove TC vortex TCDI Synthetic TC obs, Liou and Sashegy (2011) TCDI Generate vortex from TCDI (nudge MSLP) Insert vortex DI CNTL CNTL: Standard 3DVAR Initialization DI: 3D Dynamic Initialization to analysis momentum ua (12-h relaxation) after 3DVAR TCDI: Tropical Cyclone Dynamic Initialization (TC component is dynamic) after 3DVAR TCDI/DI: Run TCDI, then run DI TCDI/DI Warm Start 12-h forward DI ) TCDI Run forecast model

  4. COAMPS-TC Overview Current and Future Capabilities Atmospheric Ensembles Ocean Ensembles • Initial Cond. Perturbation:ET, EnKF • Physics Perturbations:PBL, Convection… • Lateral BCs: Global ensemble (NOGAPS) • Probabilistic Products: Intensity, track… • Initial Cond. Perturbation:ET • Physics Perturbations:PBL, Fluxes… • Lateral BCs: NCOM • Probabilistic Products: Mixed layer, OHC.. Atmospheric Analysis Ocean Analysis • Navy Coupled Ocean Data Assimilation (NCODA)System • 2D OI: SST • 3D MVOI, 3DVAR: T, S, SSH, Ice, Currents • Complex Data Quality Control • Initialization:Stability check • Complex Data Quality Control • Relocation of TC in background • Synthetic Observations: TC vortex • NAVDAS 3DVAR: u, v, T, q, TC option • Initialization:Digital Filter Option • TC Balance Step: (underway) Ocean Models Atmospheric Model • Numerics:Nonhydrostatic, Scheme C, Moving Nests, Sigma-z, Flexible Lateral BCs • Physics:PBL, Convection, Explicit Moist Physics, Radiation, Surface Layer • TC Tools: Moving nests, dissipative heating, spray parameterization, shallow convection • NRL Coastal Ocean Model(NCOM) • Numerics:Hydrostatic, Scheme C, Nested Grids, Hybrid Sigma/z • Physics:Mellor-Yamada 2.5 • Wave Models (WWIII and SWAN) • Generalized Coupling Layer (ESMF) The Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) is a registered trademark of NRL

  5. COAMPS-TC Control (CNTL) Setup

  6. COAMPS-TC Nest Setup 3 Domains: 45/15/5 km 45 km grid fixed Inner 2 grids (15/5-km) move with the TC

  7. DI Case Study: 2011 Hurricane Irene (09L) 2011082518, Cold Start (Domain 3) 10-m Winds (kt) Sea Level Pressure (hPa) • During DI, the winds are held quasi-constant • 3DVAR is not able to produce gradient balanced vortex, rapid adjustment to winds during DI

  8. 2011 IRENE (09L) TCDI CNTL DI TCDI/DI

  9. Wind Structure Verification (t=0 h) 10-m Winds (kt) COAMPS-TC using CNTL COAMPS-TC using DI Hurricane Irene (09L), 2011082512 H*WIND COAMPS-TC using TCDI/DI H*WIND courtesy NOAA/AOML/HRD Powell et. al (2010)

  10. Case Study: 08W (2011) Ma-On JTWC Best Track in black COAMPS-TC in color CNTL TCDI/DI 10 kt 15 cases Significant intensity error reductions for Ma-On by using TCDI/DI

  11. Case Study: 07L (2010) Earl NHC Best Track in black COAMPS-TC in color CNTL TCDI/DI 10 hPa 13 cases Significant intensity error reductions for Earl by using TCDI/DI

  12. Case Study: 12L (2011) Katia CNTL TCDI/DI NHC Best Track in black COAMPS-TC in color TCDI/DI does not over-intensify Katia as much as CNTL earlier, and gets rapid deepening better

  13. Track Error: Homogenous Large Sample Years: 2010-2011 Atlantic Storms: Danielle, Earl, Igor, Irene, Katia, Maria, Rina, Julia Western North Pacific storms: Chaba, Fanapi, Ma-On Cases: 120 Initial intensity < 990 hPa ALL cases TCDI/DI (blue curve) has lower track error for ALL cases and < 990 hPa

  14. Intensity Error: Homogenous Large Sample Years: 2010-2011 Atlantic Storms: Danielle, Earl, Igor, Irene, Katia, Maria, Rina, Julia Western North Pacific storms: Chaba, Fanapi, Ma-On Cases: 120 ALL cases Initial intensity < 990 hPa TCDI/DI (blue curve) has lowest intensity error for ALL cases and < 990 hPa cases with more statistical significance, and further reduced errors

  15. Summary • Three different TC initialization schemes have been developed, tested with COAMPS-TC • TCDI: tropical cyclone vortex spun-up • DI: Full 3D dynamic initialization to analyses winds • TCDI/DI: Run TCDI, then run DI • TCDI/DI is shown to have superior performance • Average intensity errors reduced by 3-5 hPa and 2-3 kts over all lead times • Average track errors reduced by 10-30 nm • Better for intense initializations (< 990 hPa) • The dynamic initialization procedures allow model physics spin-up and “less shock” • Future work • DI to satellite observed heating profiles

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