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New Ocean Subsurface Thermal Observations for Typhoon Intensity Research Lin et al. GRL 2013; Pun et al. PIO 2013a; GRL 2013b I-I Lin*, Peter Black+; Jim Price^, Shu-Yi Chen# , Pat Harr!, C-C Wu*, Iam-Fei Pun^, Eric DAsaro~ et al. *ACTS

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New Ocean Subsurface Thermal Observations for Typhoon Intensity Research

Lin et al. GRL 2013; Pun et al. PIO 2013a; GRL 2013b

I-I Lin*, Peter Black+; Jim Price^, Shu-Yi Chen# , Pat Harr!, C-C Wu*, Iam-Fei Pun^, Eric D’Asaro~ et al. *ACTS +Naval Research Laboratory, USA ^ Woods Hole Oceanographic Inst. USA # Univ. of Miami, USA !Naval Postgraduate School, USA ~ University of Washington, USA

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Little Improvement in TC intensity forecast in the past 20 years

Rappaport et al. BAMS 2012 (AMS)

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Intensification of cyclones (e.g. Gray 1979; Emanuel 1999)

Ambient ocean (SST + subsurface condition)

since 70’s e.g. Leipper and Volgenau 1972; Holliday and Thompson 1979; Shay et al. 2000;Lin et al. 2005; Goni et al. 2009...)

Ambient atmosphere (wind shear etc.)
Cyclone structure

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Case 1: Supertyphoon Megi: Cat 5:160 kts observed on 12 Z 17 Oct. 2010, 25 kts above 135 kts cat 5 threshold) Case 2: Typhoon Malakas: Cat2: 90 kts on 24 Sep. 2010 Case 3: Typhoon Fanapi: Cat 3: 105 kts on 18 Sep. 2010

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℃ ℃ ℃

$%$ #% &! !% ' ! ! "# "% $ !$ ()* !"# %%& % %!"!$

Lin et al. in review 2012

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Consider only SST is not fair for them…. need more complete ocean information

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Motivation: Proposed an improved PI (Potential Intensity) Index to include

cean’s subsurface information,

Because current PI (Emanuel 1988; Bister and Emanuel 1998) considers only Sea Surface Temperature

Acknowledgements: K. Emanuel (MIT)

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T_mix is determined by

a. Pre-tc ocean profile, b. TC translation speed,
c. TC size, d. wind speed. (Price 2009)

Emanuel 1988; Bister and Emanuel 1998 Intensity upper bound, but large error

Lin et al. GRL 2013

Simple approximation T80 (0-80m avg)

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η’ = Sea surface height anomaly (SSHA)

SSHA and UOTS

http://www.aoml.noaa.gov/phod/cyclone/data/method.html

estimate Altimeter UOTS T-profiles

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80,000 Argo Profiles from 2000-2011 Pun et al. PIO 2013a

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Current method by NOAA as TC forecast reference (Shay et al. 2000; Goni et al. 2009) New method Pun et al. PIO 2013b

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Pun et al. 2013

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Strong control of ocean subsurface (0-100m) to control

TC intensity and propose revision of Emanuel (1988)’s MPI theory, OCPI (Lin et al. 2013).

Ongoing significant subsurface warming in the WNP

typhoon MDR (Pun et al. 2013b).

New daily, 0.25∘

∘ ∘ ∘profiles from altimetry for the W.N. Pac. (typically D4 to D28) with avg. error (10-20%). Suitable for model input & accurate ocean heat content estimation. (Pun et al. 2013a).

Conclusions

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Basic idea: fix the ocean part to reduce uncertainty

Lin et al. GRL 2013

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Strong control of ocean subsurface (0-100m) to control

TC intensity. Propose revision of Emanuel (1988)’s MPI (Maximum Potential Intensity) theory, instead of using SST, include subsurface temperature.

Ongoing significant subsurface warming in the WNP

typhoon MDR.

New daily, 0.25∘

∘ ∘ ∘profiles from altimetry for the W.N. Pac. (typically D4 to D28) with avg. error (10-20%). Suitable for model input & accurate ocean heat content estimation.

TC-Ocean Interaction Interest Group tc-ocean@airsea.as.ntu.edu.tw

Conclusions

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Lin et al. MWR 2008

From 1993 From 2000

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Lin et al. MWR 2005; 2008

Scharoo et al. EOS 2006

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Peduzzi et al. Nat. C.C. 2012

What is the long-term variability of SST and subsurface condition in this MDR (Main Development Region)?

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FIGURE 9 | (a) Spatial trend patterns in altimetry-based sea level over 1993–2009 with respect to the global mean rise (a uniform mean trend of 3.3 mm/year has been removed).

After Cazenave and Remy 2011

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Pun, Lin, Lo GRL 2013

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Argo is not enough, because each grid needs a profile

perationally

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Strong control of ocean subsurface (0-100m) to control

TC intensity. Propose revision of Emanuel (1988)’s MPI (Maximum Potential Intensity) theory, instead of using SST, include subsurface temperature.

Ongoing significant subsurface warming in the WNP

typhoon MDR.

New daily, 0.25∘

∘ ∘ ∘profiles from altimetry for the W.N. Pac. (typically D4 to D28) with avg. error (10-20%). Suitable for model input & accurate ocean heat content estimation.

TC-Ocean Interaction Interest Group tc-ocean@airsea.as.ntu.edu.tw

Conclusions

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Tmix predicted by Price 2009

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Pun et al. GRL 2013a

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Upper ocean thermal structure (UOTS) by 2-layer method

4. SST:

Optimally interpolated SST from Remote Sensing System (0.25 degree, TMI+AMSR, cloud penetrating SST)

3. Mixed-layer depth (MLD):

Climatological MLD from Naval Research Laboratory (NRL)

2. The depth of 26°

° ° °C (D26):

estimated from derived D20 by multiplying a climatological raito D26/D20 from World Ocean Atlas 2001 (WOA01)

1. The depth of 20°

° ° °C (D20):

estimated from SSHA by 2-layer reduced gravity scheme

) , , ( ) , ( ) , ( ) , ( ) , ( ) , , (

1 2 2 1 1

t y x y x y x y x y x h t y x h η ρ ρ ρ ′ − + =

Pun et al. 2007

Goni et al. (1996) Shay et al. (2000)

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Devastating Cyclone Nargis (2008) > 130,000 death)

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Source: Reuters Source: Reuters

C d

Source: Reuters

Catastrophic event (> 130,000 death toll): RI took place just prior to landfall

Lin et al. GRL 2009 Killer cyclone Nargis (2008)

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C130 Airdrop

(From Dr. Eric D'Asaro, University of Washington)

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Application to ITOP field experiment (2010)

ITOP – Impact of Typhoon on the

Ocean in the Pacific

Aug.-Oct., 2010
Cooperation between Taiwan and US
Typhoon-ocean interaction
Ocean’s response to typhoon
Typhoon intensity change

D26 UOHC T100

Courtesy of ITOP

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From Eric D’Asaro (UW)