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

. H

olt

, C

. B

ish

op

, J.

Nac

ham

kin

, J

. D

oyl

e)

• 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