Tropical Cyclone Structure - 2008

I: Tropical Cyclone Formation

II: Tropical Cyclone Intensification

III: Tropical Cyclone Structure Change

Acknowledgments: Office of Naval Research, Marine Meteorology National Science Foundation, Large-Scale Dynamics USAF, 13th AF

Key science questions to be addressed in a program aimed at increased understanding and predictability of tropical cyclone

characteristics during formation, intensification, and recurvature over the western North Pacific

• Highlights– Incorporates multiple space and time scales

• Large scale controls– Global and basin-wide spatial scales– Medium-range and synoptic temporal scales

• Mesoscale organization pathways– During formation– During intensification

– Primary hypotheses with respect to:• Large-scale role in pre-conditioning• Mesoscale organizational pathways leading to construction of a potential

vorticity monolith– Role of low-level convergence associated with deep convective cells– Stratiform regions of mesoscale convective systems

• Relative roles of environmental and vortex structures in determining the evolution of the outer wind structure

– In tandem with the THORPEX Pacific Asian Regional Campaign (T-PARC)

Tropical cyclone formation, structure and structure change:Challenges to Maritime Operations

• Variety of conditions from which a tropical cyclone may form over the western North Pacific

Warning graphics from the Joint Typhoon Warning Center for TY Tokage. The shaded region defines the danger area to be avoided. This area is based on the uncertainty associated with track and outer wind structure over the ensuing five days.Note:The danger area nearly covers the entire East China Sea for a period of at least 5 days.The change in track forecast from straight to recurvature, which may be due to the influence of the outer wind structure

Pre-TY Tokage monsoon depression TY Tokage 0000 UTC 14 October 2004

TY Tokage: 0000 UTC 14 October 2004 TY Tokage: 1200 UTC 15 October 2004

• Midget tropical cyclones often develop in narrow zone along the periphery of a monsoon gyre or in association with an upper-level trough

For this small tropical cyclone, the danger area is only 4 deg. in diameter and there is no change in track

http://www.nrlmry.navy.mil/tc_pages/tc_home.html

TS Danas (11W) 1200 UTC 8 Sep 2007 TS Danas (11W) Danger area graphic 0000 UTC 9 Sep 2007

Tropical cyclone formation, structure and structure change:Challenges to Maritime Operations

How does the large-scale atmosphere and ocean environment control the mesoscale

environment prior to tropical cyclone formation?

Objective: medium-range predictability of the tropical large-scale environmental factors that influence tropical cyclone formation

Large-scale modes of variability

What are the relative roles of the primary mesoscale mechanisms (bottom-up and top-down) in determining

the location, timing, and rate of tropical cyclone formation in the monsoon trough environment of the

tropical western North Pacific?

Pre-Fitow (10W 2007) disturbance Pre-Man-Yi (04W 2007) disturbance

Objective: Increased predictability associated with the location, timing, and rate of tropical cyclone formation over the western North Pacific

http://www.nrlmry.navy.mil/sat_products.html http://www.nrlmry.navy.mil/sat_products.html

19o 10o

What are the relative roles of environmentally-induced and vortex-generated mechanisms versus

cyclogenesis-determined initial conditions in determining the outer wind structural evolution of

western North Pacific tropical cyclones?

Objective: Increased understanding and predictability of factors that impact the evolution of the outer-wind structure of an intensifying tropical cyclone over the western North Pacific.

Mesoscale Forcing

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Increase in forecast uncertainty over tropical and midlatitude regions often occurs due to tropical cyclones and the movement of tropical cyclones into the midlatitudes

TY Tokage, October 2004Tracks from the JMA ensemble prediction system

Tracks supplied by Dr. T. Nakazawa

What are the key structural aspects of the tropical cyclone and its environment that limit the predictability of recurvature and

the start of extratropical transition over the subtropical western North Pacific?

Ensemble Prediction System from the European Center for Medium Range Weather Forecasts (ECMWF)

5-Day Forecasts associated with the Extratropical Transition of TY Maemi (2003)

Agreement among membersimplies high predictability

Large spread among members implies decreased predictability

Graphic supplied by Prof. S. Jones and D. Anwender

TY Maemi

North

NW

TMI 85H 9-22-05 1443Z

NOAA 43 1430-1520Z 10,000’

Satellite – Aircraft Comparisons

Hurricane Rita

Graphic supplied by J. Hawkins

Observing Platforms (1 August – 30 September)• NRL P-3/ NCAR ELDORA/ DWL lidar/ GPS

Dropwindsondes• 50/50 funding split between NSF and ONR• Operation from Andersen AFB, Guam, Kadena AFB, Okinawa,

Atsugi NAF, Japan• Total of 150 research hours• 450 dropwindsondes (30 sondes per mission)

• USAF Reserve 53rd Weather Squadron (Hurricane Hunter) WC-130J

• Funding from ONR and USAF• Operation from Andersen AFB, Guam, Kadena AFB, Okinawa,

Yokota AFB, Japan• Dropwindsondes• Stepped Frequency Microwave Radiometer• AXBTs, Drifting Buoys

• Other Components• DOTSTAR• Driftsondes

– Launch from Hawaii– 20 balloons with dropwindsonde gondolas– 40 dropwindsondes per gondola

• Satellite: MTSAT rapid scan, Polar orbiting platforms

Combined missions during tropical cyclone formation Use of Eldora to measure characteristics associated with deep convection

Use of WC-130 to measure the environmental characteristics

Pre- TY 10W (Fitow) Disturbance

Japan, Atsugi, NAF

Okinawa, Kadena AFB

T-PARC/TCS-08 Components

Guam, Andersen AFB

ET characteristics, forcing of downstream impacts, tropical/midlatitude interactions, extratropical cyclogenesis

Extratropical Transition (ET – recurvature), Downstream Impacts

Midlatitude operating regionNRL P-3, FALCON

TY Nabi, 29 Aug – 8 Sep, 2005

Large-scale circulation, deep convection, monsoon depressions, tropical waves, TC formation

Tropical Measurements

Tropical operating regionDriftsonde, NRL P-3, DOTSTAR, WC-130

Subtropical operating regionDriftsonde, NRL P-3, DOTSTAR, WC-130

TC track characteristics, tropical/midlatitude interaction

TC Intensification and structure changeRecurvature, initiation of ET

T-PARC and TCS-08: GLOBAL OPERATIONS

Operations center, Monterey, CA

Driftsonde center,Boulder, CO

Driftsonde release,Hawaii

Aircraft locations, andaircraft operations centers

Guam

Japan

Taiwan

Okinawa

Summary• Much recent national and international attention on TCs • Four Major Weather Forecast Problems in the Pacific• Lack of understanding of storm scale processes is the biggest knowledge gap

(basic research common to all four)• Proposing:

– First major WESTPAC field experiment since TCM93– First detailed observations of TC outer winds, genesis & life-cycle (in situ aircraft, radar,

dropsondes, lidar, remote sensing)– First measurements. to validate new and advanced satellite obs. of WP TCs– Utilize the post-CBLAST coupled ocean-wave-atmosphere modeling system as a testbed

to gain understanding of the processes as informed and constrained by the field data• Expected accomplishments:

– Increase the predictability of the environmental forcing, formation, outer wind structure and intensity of TCs over the western North Pacific

– Leverage several international efforts – GOAL: to reduce errors in TC structure and intensity forecasts by 50% within a

decade – will also increase warning times and improve ocean and wave forecasts

upgraded russian radiosonde network for ipy

Documents

small tropical cyclone

tropical cyclone formationii

midget tropical cyclones

w danger area graphic

largescale role

largescale atmosphere

mesoscale environment

largescale dynamics