Navy Research Prioritiesfor Tropical Cyclones
Simon W. Chang1 and Ronald J. Ferek2
1Naval Research Laboratory, Monterey, CA
2Office of Naval Research, Arlington, VA
62nd Interdepartmental Hurricane Conference
Charleston, SC
March 3-7, 2008
Navy Operational GoalsFor Maritime/Tropical Cyclones
• Develop and improve cogent communication and articulation of impending hazard/risk
• Accurate quantification of risk
• probabilistic
• Sensitive and adaptable to user timelines and operational constraints
• Maintain track excellence
• 5-day requirement (50/100/150/200/250 nm), multi-model ensemble
• Improve operational forecasting of TC structure and its effects
• Significant wave spectra, impact on ocean structure, storm surge, precipitation, intensity, ET
• Develop ability to operationally forecast TC genesis out to 5 days
• Maintain ATCF capability to meet user requirements
(from “Modeling and Automation Requirements in Support of NOOC”, RDML David Titley, CNMOC, 2007)
Navy Research Related to Tropical Cyclones
• Naval operations depend critically on accurate analysis and prediction of
tropical cyclones. Naval Research aligns with operational requirements.
• Office of Naval Research (ONR) has long-term, extramural, basic and applied research program in tropical meteorology. Two new research initiatives with field campaigns focused on couple atmosphere-ocean problems were launched in FY08.
• Naval Research Laboratory (NRL) has on-going basic and applied research program. Topics related to tropical cyclones are: tropical wave dynamics, predictability, deterministic and ensemble prediction systems, optimal data selection for assimilation, observation sensitivity, and targeted observations.
• The Office of the Oceanographer and Navigator of the Navy provides long-term investment for transitioning of observing and prediction systems into operations for atmospheric and ocean analysis and prediction.
Navy Research PrioritiesFor Tropical Cyclones
• Major research foci:
• Cyclogenesis and formation
• Intensification processes
• Structure and intensity changes
• Extratropical transition (ET)
• Air-sea interactions
• Companion research foci in ocean responses:
• SST
• Current and waves
• Internal structure
• Transition to operational NWP and Satellite Application systems through on-going transition programs
Navy Research PrioritiesFor Tropical Cyclones
• Current integrated programs for transition to operational NWP and Satellite Application systems:
Strong- and weak-constraint 4DVAR
Hybrid (VAR + EnKF), nonlinear data assimilation
Observation sensitivity and optimal data selection
Air-sea coupled high resolution TC model
Spectral element and discrete Galerkin, nonhydrostatic dynamic cores
Semi-Lagrangian and semi-implicit numerics
Global and mesoscale deterministic and ensemble prediction systems
Multi-sensor satellite and NWP data fusion
Following slides show some research highlights
Pre-TY Harry
Pre-TY GladysTY Fred
Tropical Cyclone Structure 2008 (TCS08) ExperimentEmphasis: To improve the capability to predict the evolution of
disturbances in the monsoon trough over the western North Pacific(genesis, structure & intensity changes, outer winds, etc.)
o Guam
Phillipines
GOAL: to reduce errors in TC structure and intensity forecasts by 50% within a decade
TCS-08 is coordinated with the international T-PARC.
TCS-08/T-PARC are jointly supported by Navy, NSF and USAF.
Research to Operation in TCS-08
• Observation assets: In 2008 NRL P-3 with Eldora, dropsonde and lidar. AFR C-130 with SFMR, dropsonde, AXBT, and drifting buoys. (First WestPac TC recon since 1993.) For 2010: drifters gliders, profiling floats, buoys, AXBT and AXCD.
• Specially tailored images of the atmosphere and ocean surface from geostationary and polar-orbiting satellites. SAR images of ocean waves.
• Numerical testbeds: NOGAPS, COAMPS®, and associated ensemble prediction systems with 3D/4D VAR data assimilation at NRL and FNMOC.
• Initial condition (SV/ET) and observation sensitivity products.
• More than 20 PIs in the research community are funded to participate.
• Observation and model data available for post-experimental analyses, basic research, and prediction system improvements.
• New discovery and invention will transition to operations through existing transition programs.
Ocean Mixed Layer Evolution in HurricanesBuilding on the Accomplishments of CBLAST
Before CBLAST: usual drag coefficient approach, mixing by KPP, Mellor-Yamada
Out of CBLAST: wind forcing via the wave based momentum calculation.
Use CBLAST Tested Ocean Observation Technologies
Major field program in WestPac planned for 2010
First workshop in Taipei March 2008
• Coupled COAMPS® with Ocean Circulation Model• Use ESMF methodology to couple COAMPS with NCOM ocean circulation and ocean wave models, in conjunction with the BEI project
• Explore the air-ocean coupled response
• New Suite of Physical Parameterizations for COAMPS-TC• New surface flux parameterization based on CBLAST observations• New microphysics development for more accurate TC intensity forecasts • Application of new Fu-Liou 4-stream radiation package to TCs• New sea spray parameterization
• New Tropical Cyclone Analysis Technique• Development of new TC analysis packages that features relocation of the TC and augmentation with synthetic observations
• Formulated in NAVDAS (3DVar) framework• Improved intensity analysis that is balanced and dynamically consistent
High Resolution NWP SystemFor Intensity Forecast
New TC Analysis: TC Isabel Observations: 940 mb, 64 m s-1
New NAVDAS TC Analysis Improves Location, Structure, Intensity and Balance
956 mb956 mb 960 mb960 mb 980 mb980 mb
67 m/s67 m/s 81 m/s81 m/s 53 m/s53 m/s
OI AnalysisStandard NAVDASNAVDAS for TC
Min. SLP for Isabel
Obs
No spray
Spray
No Spray Spray
100
10
1
0.1
Sfc. Precip. Rate (78 h) Sfc. Precip. Rate (78 h) mm h-1
New CBLAST Sea Spray Algorithm (Fairall)
implemented in COAMPS shows a more intense cyclone and better organization to the
convection for TC Isabel.
New Spray Parameterization Based on CBLAST Measurements
Ocean response in coupled COAMPS
Cold wake forms in right rear quadrant and dramatically
impacts azimuthally averaged flux.
Katrina forces a strong cold wake that has an asymmetric impacts on fluxes
001800
Cold wake
NW
SESW
NETotal Heat Flux
SST Difference: (48h-initial) 12Z 29 Aug 2005
The SST decreases by 7°C in the wake over the 48h period.
Evolution of Total Heat Flux
coupled
coupled uncoupled
uncoupled
08/28/05 2135 UTC
2005082821 2005082821
2005082902 200508290208/29/05 0229 UTC
TRMM
TRMM
Model-simulated radar reflectivity indicates that rainband structure is relatively insensitive to the coupling when compared to TRMM estimated precipitation
Comparison of Structure Forecast in coupled and uncoupled COAMPS
1 2 3 4 5 6
7 8 9 10 11 12
13 14 15 16 17 18
19 20 21 22 23 24
25 26 27 28
1 2 3 4 5 6
7 8 9 10 11 12
13 14 15 16 17 18
19 20 21 22 23 24
25 26 27 28
For probabilistic intensity forecasting: Mesoscale Ensemble
ET+Pert physics 48-h forecasts from 00 UTC 09 July 2005 (TC Dennis)
Physics perturbations
further increase
variability in intensity (~987 to
1002 hPa) as well as
track among ensemble members (T
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, C
. B
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, J.
Nac
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, J
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• Adjoints of the NOGAPS-NAVDAS are used to calculate the impact of observations on forecast error (Langland and Baker, Tellus 2004).
• The impact of each type of observation: rawinsonde,
dropsonde, particular satellite channels, or temperature vs. wind or humidity can be easily quantified using this method
Evaluate the Observation Impact
KATRINA case Observations at 00UTC 27 Aug 2005
analysis time (+/- 3 hr)
Forecast error reduction Forecast Error Increase
Rawinsondes
19 out of 34 reduce 24 h forecast error
Dropsondes
11 out of 16 reduce 24h forecast error
COAMPS Moist AdjointAdjoint Sensitivity for Tropical Cyclogensis
COAMPS Moist AdjointAdjoint Sensitivity for Tropical Cyclogensis
J. Doyle, C. Amerault, C. Reynolds
Asymmetric Structure2007082906
http://agora.ex.nii.ac.jp/digital-typhoon
TC Fitow (Western Pacific)•Adjoint to nonhydrostatic COAMPS® model•Exact adjoint to 6 class microphysics, 1.5 order TKE PBL, and simple cumulus scheme
•Moist adjoint sensitivity can provide insight into the predictability of tropical cyclones
Initial Perturbation Total Energy & SLP
Optimal perturbations computed from moist adjoint (24 h)
P’=-18 mbU’=30 m s-1
Final Perturbation Total Energy & SLP
(24 h)
Targeting Implication: Observe Convection in NE
Quadrant for This Case
Navy Research Priorityin Tropical Cyclones
SUMMARY
• Navy Research programs can contribute to Research Priority topics in Interagency Strategic Research Plan for Tropical Cyclones: The Way Ahead. There are strong basic and applied research programs in all three interagency priority topics:
General Research and NWP Modeling
NWP Model Development
Observations and Observing Strategies
• Navy integrated research programs in tropical cyclones are being executed in collaboration with other federal agencies, national and international research communities, and operational centers.
Navy Research Priorityin Tropical Cyclone
The End