Comparison of Multi-Day Convective-Environmental Evolution between - - PowerPoint PPT Presentation
Comparison of Multi-Day Convective-Environmental Evolution between TC Developing vs. Non-Developing Disturbances over the Western North Pacific Minhee Chang ( ) 1 , Chang-Hoi Ho 1 , Myung-Sook Park 2 1 School of Earth and Environmental
Seoul National University
Minhee Chang (張敏姬)1, Chang-Hoi Ho 1, Myung-Sook Park 2
1 School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea 2 Korea Institute of Ocean Science & Technology, Busan, South Korea
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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Tropical disturbances TC developing? Developing disturbance Non- developing disturbance
Yes No
than a hundred of tropical disturbances exists, but
pathways regarding how the tropical disturbance can develop into a tropical cyclone; top-down hypothesis (Simpson et al. 1997; Bister and Emanuel 1997) and bottom-up hypothesis (Hendricks et al. 2004; Montgomery et al. 2006).
| Introduction | Motivation | Objective | Data and methodology | Part 1 | Part 2 | Summary |
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Zawislak and Zipser 2014a; mid-level vorticity strength by Zawislak and Zipser 2014b; latent heating maximum location by Park and Elsberry 2013) of deep convective cloud have been emphasized by previous researches.
series of diurnal convective bursts (Zehr 1992; Davis and Ahijevych 2012). Satellite TRMM (non-sun- synchronous satellite)
Aircraft radar
(Zehr 1992) Convection area (fraction) Time
Hurricane Matthew (2010)
Time Convection area (radius) (Davis and Ahijevych 2012)
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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radiative forcing (Webster and Stephens 1980; Gray and Jacobson 1977; Melhouser and Zhang 2013; Tang and Zhang 2016), thus, tend to have morning maxima and afternoon minima (Gray and Jacobson 1977).
TC genesis (Melhauser and Zhang 2013; Tang and Zhang 2016).
(Zehr 1992) Convection area (fraction) Time
<Diurnal radiative forcing>
convective instability differential cooling large-scale environment cooling
Relative vorticity [x10-5 s-1] Height Height Height Local Standard Time (Tang and Zhang 2016)
Diurnal Nighttime Daytime
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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(1) In what percentage, mCB is related to TC development and non-development processes? (2) If mCB and TC development does not have one-to-one relationship, what other element modulates TC development and non-development processes? (3) Can a tropical cyclone develop without mCB and how? (4) What are the characteristics of TC development without mCB?
mCB TC formation
?
mCB & large-scale condition TC formation
?
Without mCB TC formation
?
Without mCB & large-scale condition TC formation
?
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
6 Domain : western North Pacific
(100–180˚E, 0–35˚N)
Period : Year of 2007–2009
Type Time resolution Space resolution Variables Name
Geostationary satellite data 1 hourly 4km × 4km IR(10.8 μm), WV(6.7 μm) brightness temperature MTSAT-1R Reanlaysis data 3 hourly 1.25⁰ × 1.25⁰ u, v, omega, T, PV, height, RH, q MERRA reanalysis 1 3 hourly 0.5⁰ × 0.625⁰ MERRA reanalysis 2 1 daily 0.25 × 0.25 SST OISST Track data 6 hourly – TD formation time JTWC best track 6 hourly – LAT, LON IBTrACS best track 3hourly – LAT, LON Tropical cloud cluster track
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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Developing disturbances (80) : 5 days prior to TC formation Non-developing disturbances (383) : 5 days including decay of disturbances.
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7
TC formation day Largest CB day
Day 1 Day 2 Day 3 Day 4 Day 5
Vortex tracking Vortex tracking Vortex tracking
positions are obtained.
600 hPa Potential Vorticity TC Peipah (2007) vortex track
Longitude Latitude
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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running mean (thick solid line).
increment satisfying four thresholds (Δt ≥ 6 h, ΔA ≥ 5,000 km2, max(A) ≥ 15,000 km2, and ΔA/Δt ≥ 500 km2 h1) for at least two consecutive days.
500 km radius
TC formation
e.g., Pre-Higos (24-30 Sep 2008)
IR–WV 600 hPa PV
`
Δt ΔA max(A)
mCB
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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67.5% (54 / 80) 32.5% (26 / 80) 13.8% (53 / 383) 86.2% (330 / 383)
Tropical disturbances TC developing? Developing disturbance Non- developing disturbance Yes No mCB
D_w D_wo Yes No mCB
ND_w ND_wo Yes No “D” : Developing “ND” : Non-developing “_w” : with mCB “_wo” : without mCB
with mCB (D_w).
without active convection (D_w/o).
(ND_w).
Deep convective area [104 km2] Time
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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for both D_w and ND_w. But the strength for D_w is significantly stronger than ND_w on Days 3–5.
are persistently maintained. But that for ND_w are maintained in diurnal signal.
suddenly strengthens prior to TC genesis.
(Shading) (contour line)
Time p
Potential vorticity
strengthens due to deep convective updrafts. (Wang 2014)
[10-6 s-1]
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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level from Day 1 to 5 is maintained.
extremely dry (< 70%) until Day 2.
Time p
[%]
×: vortex center 3⁰ radius circle 8⁰ radius circle | Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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[m s–1]
mostly under 14 m s-1 within 8⁰ radius circle.
vortex center is larger than 14 m s-1, which significantly decrease on Days 4– 5.
radius circle is covered with vws larger than 14 m s-1.
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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strengthening for tropical cyclogenesis. Difference in D_w and ND_w.
needed for D_wo.
32.5% (26 / 80) 86.2% (330 / 383)
Low-level inflow Relative vorticity mCB Vertical wind shear
67.5% (54 / 80) 13.8% (53 / 383)
mCB
(Chang, M., Ho, C.-H., Park, M.-S., Kim, J., & Ahn, M.-H., 2017, JGR)
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
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(i) suppressed convection in the preceding days (ii) sudden intensification of low-to-mid relative vorticity (iii) strong vertical wind shear diminishes later
Abrupt TC formation may possibly induced by external forcing.
32.5% (26 / 80)
27 28 29 30 31 1 2 3 4 October November
TC Peipah (formed on Nov 3, 2007), a case with the most representative feature, is chosen for a case study.
15
Cowan et al. 2008; 2013)
2015; Bentley et al. 2017)
(Bentley et al. 2017)
16 L L L H L H L H L H L
IR BT (shading, K), ℎ850 ℎ𝑄𝑏
′
(contours, m), (𝑣, 𝑤)200 ℎ𝑄𝑏 (arrows, ≥ 15 m s-1) ℎ′ (contours, m), 𝑈′ (shading, K) PV (contours, PVU) on 𝜄350 𝐿 surface ω (green (+), purple (-), Pa s-1) PV (black contours, PVU), ω (green (+), purple (-), Pa s-1)
| Introduction | Motivation | Objective | Data and methodology | Result | Summary |
17 Effect of TUTT
(Tropical Upper-Tropospheric Trough) (Sadler 1976; 1978)
𝐯 > 𝟏 and
𝝐𝜼 𝝐𝒚 < 𝟏
−𝐯 ∙ 𝝐𝜼 𝝐𝒚 > 𝟏
Positive vorticity adv.
(http://tornado.sfsu.edu) (https://www.meted.ucar.edu/)
Tropical Transition
(Davis and Bosart 2003; 2004) Baroclinic interaction between upper- level trough and surface extratropical low. (https://www.atmos.illinois.edu)
PV intrusion and anticyclonic wave breaking
(McIntyre and Palmer, 1983; Waugh and Polvani 2000; Galarneau et al. 2015; Bentley et al. 2017) Rossby wave amplification and anticyclonic wave breaking destabilizes troposphere by vertical mixing. (Bentley et al. 2017)
(Chang, M., Ho, C.-H., Chan, J.C.L., Park, M.-S., Son, S.W-., & Kim, J., JGR, in preparation)
(1) In what percentage, mCB is related to TC development and non-development processes? (2) If mCB and TC development does not have one-to-one relationship, what other element modulates TC development and non-development processes? (3) Can a tropical cyclone develop without mCB and how? (4) What are the characteristics of TC development without mCB?
| Introduction | Motivation | Objective | Data and methodology | Part 1 | Part 2 | Summary |
18 mCB TC formation : 67.5 % (during 2007−9) mCB & large-scale condition TC formation : vertical wind shear Without mCB TC formation : 32.5 % (during 2007−9) : baroclinic interaction of surface easterly wave and upper level trough