Joint research proposal: The Kuroshio and its effects on regional climate

Fangli Qiao First Institute of Oceanography, SOA, China

12-13January, 2015 Yokohama, Japan

qiaofl@fio.org.cn

p  I have to cancel this important and interesting trip to Yokohama, Japan, since my visa is not available till now;

p  Hope you have a successful and fruitful meeting;

p  Special thanks to Prof. Xiaopei Lin, Ocean University of China who will present on behalf of me.

Outline

1. Non-breaking surface wave induced mixing, Bv 2. Surface wave in ocean and climate models 3. FIO-ESM with surface waves 4. Kuroshio simulation and prediction 5. Summary

1. Non-breaking surface wave induced mixing, Bv

Motivation Two of the common problems nearly all models faced: (1) OGCMs: Simulated SST is overheating in summertime, and mixed layer depth is too shallow while the thermocline is too weak (Martin 1985, Kantha 1994, Ezer 2000, Mellor 2003).

(2) Climate Models: Tropical bias for all CGCMs, such as too cold tongue, wrong Atlantic SST gradient

MLD in OGCM

ü  Observation ü  Model from POM

6

MLD in CMIP5 models: the black thick is data, and the dashed black is multi-model mean.

Huang et al, 2014, JGR

Some related work: 1. Phillips, O. M. , 1961: “Although the use of potential theory has been very successful in describing certain aspects of the dynamics of gravity waves, it is known that in a real fluid the motion can not be truly irrotational”. And Phillips (1974): Wave is proved to be too feeble for any dynamic consequence

2. Wave enhanced turbulence (Craig & Banner,1994; Terray, E.A. et al, 1996; Le Ngoc LY 2000; Burchard &Karsten, 2001; Mellor & Blumberg, 2004): Wave-breaking

3. Wave-current interaction (Xie et al 2002, 2003): 2-D

4. Mellor et al, 2003JPO, and 2008 J. Atmos. Ocean. Technol [wave breaking]

While these studies (wave-breaking) have shown some improvements in simulation, the surface wave effects are mostly limited to the top few meters, and too weak

Lack of mixing in the upper ocean

As the mixing process is essentially an energy balance problem, waves, as the most energetic motions at the ocean surface, should play a controlling role. Unfortunately, in

most ocean dynamics studies, wave motions have always been treated separately from the ocean circulation. Surface wave: 60 TW, Circulation: 4 TW

E(K) is the wave number spectrum which can be calculated from a wave numerical model. It will change with (x, y, t), so Bv is the function of (x, y, z, t). Qiao et al, 2004, 2010, 2016

If we regard surface wave as a monochramatic wave, 3 ( 3 ) ( 3 ) ,kz kz

v sB A k e A u eα ω α− −= =

Bv is wave motion related vertical mixing instead of wave breaking.

Stokes Drift

( ) { } ( ) { }12

2exp 2 exp 2Vk k

B E k kz dk E k kz dkz

α ω⎛ ⎞∂

= ⎜ ⎟∂ ⎝ ⎠

∫∫ ∫∫v v

v v v v

Although the horizontal scale of surface wave, 100m, is much smaller than that of circulation, however, the wave-induced vertical velocity in the upper ocean could be stronger than vertical current turbulence velocity.

Laboratory experiments:

Wave tank: 5m in length with height of 0.4m and width of 0.2m. To generate temperature gradient through bottom cooling of refrigeration tubes, and temperature sensors are self-recorded with sampling frequency of 1Hz.

Bottom of wave tank

Top of wave tank

Refrigeration tube

Temperature sensor

(1) Temperature evolution in natural condition

(2) Temperature evolution with wave

Dai and Qiao et al, JPO, 2010

Experiment results without and with waves

Evolution of water temperature without waves. (a) Observation; (b) simulation.

zT Tkt z z

⎛ ⎞⎜ ⎟⎝ ⎠

∂ ∂ ∂=

∂ ∂ ∂

kz=k0+Bv

Simulation results with waves

Evolution of water temperature with waves. Left: observation; right: simulation; (a,b) 1.0cm, 30cm; (c,d) 1.0cm, 52cm;

Observation evidences

Vertical profiles of the measured dissipation rates εm (dots), and those predicted by wave εwave (black lines) and the law of the wall εwall (pink lines) at Station S1~S12 (in m2 s−3). Observation is conducted in SCS during October 29 to November 10, 2010. Huang and Qiao et al, 2012, JGR

2. Bv in ocean and climate models

We apply Bv into:

Bohai Sea

Yellow Sea

East China Sea

And

South China Sea

Xia et al, JGR,2006

3-D coastal circulation model (Special Issue on JGR, 2006 at http://www.agu.org/journals/ ss/CHINASEAS1/ )

385 390 395 400Latitude(1/10° N)

T_Bohai section

-25

-20

-15

-10

-5

0

H(m)

17.51818.51919.52020.52121.52222.52323.52424.52525.526

38 38.5 39 39.5 40 40.5-30

-25

-20

-15

-10

-5

0

18

18.5

19

19.5

20

20.5

21

21.5

22

22.5

23

23.5

24

24.5

25

25.5

26

Observation in summer

Lin et al, 2006 JGR

38.5 39 39.5 40-30

-25

-20

-15

-10

-5

0

11121314151617181920212223242526

(a) POM

POM+Bv

3-D coastal models

Along 35N transect in Aug.

World Ocean Atlas

With wave-induce mixing

Without wave effects

Pacific Atlantic Indian Pacific Atlantic

Along 35S transect in Feb.

35N

35S

3-D global ocean circulation models

Along 35N transect in Aug.

World Ocean Atlas

With wave-induce mixing

Pacific Atlantic Indian Pacific Atlantic

Along 35S transect in Feb.

Vertical Temperature Distributions

Without wave-induce mixing

The two lines represent the whole upper ocean: Zonal (x-direction) and upper 100m (z-direction) averaged correlation coefficient (t).

Black, POM2008 without wave effects; Green: with wave breaking (and IW) suggested by Mellor (2004, JPO); Red: with Bv

MLD of the Southern Pacific in Feb.

MLD of the Northern Atlantic in Aug.

World Ocean Atlas

With wave-induce mixing

Without wave-induce mixing

MLD in summer (Qiao et al, OD, 2010)

Time evolutions of global mean SSTs simulated in Exp. N (blue line for without Bv) and Exp. W (pink line for with Bv), and that

from the WOA01 climatology (black line). Huang et al, AOS, 2008

Climate model 1: FGCM0

Data

With Bv No Bv

Bv effect

Water vapor transport in Australian-Asian Monsoon area

Song and Qiao et al, 2012, JAS

Climate model 2: CCSM3

CCSM3+Waves

CCSM3: 251-300a

WOA

The isotherm of 27℃

50a averaged SST (251-300a).

Up: Exp1-Levitus, Down: Exp2-Exp1

Exp1: CCSM3 without Bv

Exp2: with Bv

3. FIO-ESM with surface wave

Framework of FIO-ESM version1.0

Land carbon CASA’

Atmosphere CO2 transport

Ocean carbon OCMIP-2

Wave-induced mixing, Qiao et al., 2004

FIO-ESM for CMIP5

Descriptions of the FIO-ESM

Physical models l ATM: CAM3.0, T42L26 l LND: CLM3, T42 l OCN: POP2, 1.1o*0.3~0.5o, 40 vertical layers l ICE: CICE4, 1.1o*0.3~0.5o l WAV: MASNUM wave model, 2o*2o

l Wave-circulation coupling: based on the wave-inducing mixing

SST absolute mean errors for 45 CMIP5 models

Sea ice annual cycle in Arctic

Future Experiment 2006-2100

RCP85 RCP60 RCP45 RCP26

Historical run

3.8℃

Centurial Future Projections

1

1.2

1.4

1.6

1.8

2

2.2x 1013

January

RCP2.6RCP4.5RCP6.0RCP8.5

1.2

1.4

1.6

1.8

2

2.2

2.4x 1013

February

1.2

1.4

1.6

1.8

2

2.2

2.4x 1013

March

1.2

1.4

1.6

1.8

2

2.2

2.4x 1013

April

1

1.2

1.4

1.6

1.8

2

2.2x 1013

May

0.8

1

1.2

1.4

1.6

1.8

2x 1013

June

4

6

8

10

12

14

16x 1012

July

0

5

10

15x 1012

August

2000 2020 2040 2060 2080 21000

2

4

6

8

10

12x 1012

September

2000 2020 2040 2060 2080 21000

5

10

15x 1012

October

2000 2020 2040 2060 2080 21000

0.5

1

1.5

2x 1013

November

2000 2020 2040 2060 2080 21000.5

1

1.5

2x 1013

December

Unit: m2

Time series of Arctic sea ice extent from RCP run. By including Bv, the ice-free will not appear in summer for RCP 6.0. It may appear at the end of 21st century for RCP8.5

4. Kuroshio simulation and prediction

Based on the climate model with surface wave, FIO-ESM, the volume transport of Kuroshio in the East China Sea is simulated and predicted.

1900 1950 2000 2050 2100

17

18

19

20

Year

Sv

HistoryRCP26RCP85

Summary

(1)  The 8 years China-Japan cooperation on Kuroshio investigation during 1986-1993 greatly enhanced the scientific understanding of this western boundary current;

(2)  The effects of Kuroshio on regional climate change should be an interesting topic which our institute will focus on, and joint research is highly expected.

Thank you for your attention