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This study explores a new airborne observing strategy using a combination of AXBT's and GPS dropsondes to gather observations of the atmosphere and ocean during the formation, inner-core, and mature phases of tropical cyclones. The technical approach involves optimized flight plans, real-time data transmission, and joint flights with multiple aircraft. Key results show that the formation and intensification of TCs are influenced by underlying ocean eddies, and future plans include developing diagnostic analysis tools and operational data archives for improved TC prediction models.
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Ocean observations in developing and mature TC’s based on a new airborne observing strategy: 'Combo' deployments of AXBT’s and GPS dropsondes from long-endurance, multi-altitude reconnaissance flights P. G. Black1 and J. D. Hawkins2 1SAIC, Inc./Naval Research Laboratory, Monterey, CA 2Naval Research Laboratory, Monterey, CA Collaborators: E. D’Asaro & M. Ohmart- U. Washington; P. Harr, A. Penny, C. DePalma, R. Creasey and H. Hornick- NPS; Y. Jin, S. Chen, J. Cummings, S. Wang, J. Solbrig & M. Surrat- NRL; G. Elliott & G. Foley- BoM-Au; M. Kucas, R. Ballucanag, K. Bench & C. Morris- JTWC; P. Niiler- Scripps; J. Kerling- NAVO; Robert Lee- CORLEE, Lld.; LtCol Roy Deatherage, 53rd WRS-AFRC 65th Interdepartmental Hurricane Conference (IHC) 28 February – 3 March, 2011 Miami, Florida
Objectives: • Observe atmosphere and ocean during formation phase of candidate TCs • Observe TC Inner-Core surface wind field and ocean structure, especially during RI/RD. • Observe mature phase ‘cold wake’ formation, structure and time evolution. Technical Approach: • Design and execute WC-130J aircraft flight plans for optimal achievement of ITOP goals. • Employ two WC-130J aircraft/crews with SFMR, AXBT and buoy-deployment capability- transmit data in real-time. • Conduct joint flights of 53rd WRS WC-130J and DOTSTAR ASTRA.
ITOP Operations • Aircraft Module • Synoptic surveillance module (Taiwan-NTU/ CWB) • Taiwan moorings (4) • U. Miami ASIS/EASI moorings (2) • Satellite image acquisition (NRL) • SAR image acquisition (U. Miami) • R/V Revelle + 4 Taiwan research vessels • Ship-based AUVs (16) ITOP DOTSTAR/WC-130J joint observations: Fanapi (2010) WC-130J DOTSTAR- ASTRA 0000 UTC, Sept. 17th 0000 UTC, Sept. 18th
WC-130J Ocean Sensor Deployments . MOOS Drifters - Floats NRL Mobile Ocean Observing System AXBT/Launcher
26C Isotherm Depth, D26 Fanapi Malakas Megi ITOP TC tracks and ARGO ocean temperature profiles near point of development showing range of D26 values (Courtesy I-I Lin): CAT 3 TY Fanapi (70m) CAT 2 TY Malakas (40 m) CAT5 STY Megi (120m)
Ridges generate internal tide Geometry makes a focus point 9 hr AXBT repeat pattern 70m vertical displacement of 20C isotherm Temp Diff from Mean Semi-Diurnal Tide in the Philippine Sea Model Ko OBS AXBT
Fanapi development modulated by ocean features! TC Fanapi 14 14 13 1) Slow development over Warm pool-cold eddy 12 TC Fanapi 14 13 2) Formation over WARM EDDY 12
Fanapi 13 Sept Warm/Cold Eddy 60 m variation in 26oC isotherm ITOP AXBT Data 100 m variation in 26oC isotherm Semi-Diurnal Tides 50 m variation in 26oC isotherm over 9 hr Fanapi 14 Sept Warm Eddy Eddy ocean structure variability greater than that from diurnal tides!
Surface 12 Sept, 2010 Surface 13 Sept, 2010 700 MB 13 Sept, 2010 700 MB 12 Sept, 2010 5.FANAPI genesis over warm eddy 3.Sfc vortex develops over warm/cold eddies 1.Wave growth over deep D26 6.Vertical development established 4.Slow vertical development 2.Weak wave vertical consistency
25 20 125 130 OHC26 KO EASNF 19 Sept Typhoon Fanapi region Major Eddy Locations Cold Warm A1, A2, A3 moorings
AMSR-E Fanapi Cold Wake Monitoring: Typhoon Phase 20 Sept 19 Sept NTU Lin NRL Hawkins Eddies modulate cold wake
Cold Eddy Eddy Boundary 50 m Landfall Vmax (kt) 100 m D26 24 25 26 27 28 29 30 Warm Eddy Sept, 2008 Similar to TCS08 STY Jangmi RI/RD episode JangmiRapid Intensification/Decay Coincides with passage over warm/cold eddy pair prior to Taiwan landfall ITOP/TCS10STY Megi undergoes RI over large D26 and OHC26 region RI RD
Surface Max Winds (m s-1) 25 26 27 28 29 Jangmi TCS08 COAMPS-TC Coupled and Uncoupled Intensity Simulation Eddy Landfall (Courtesy Y. Jin) • Coupled COAMPS-TC continued RI until cold eddy passage and began weakening following passage, prior to landfall. • Uncoupled COAMPS-TC began weakening only after landfall.
Key Results • TC formation process modulated by underlying ocean heat content structure • TC Rapid Intensification/Rapid Decay (RI/RD) cycle strongly modulated by • underlying ocean eddy pairs • Warm and cold eddies modulate cold wake • Warm and cold eddy pairs contribute to timing of RI/RD Future Plans • Develop additional diagnostic analysis tools for TPARC/TCS08 and ITOP/TCS10 aircraft data and companion COAMPS-TC model output fields. • Develop operational AXBT/Sonde ‘Combo’ TC data archive to assist in initializing and validating coupled TC prediction models