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TRACERS : From Description to Quantification Monika Rhein, IUP Bremen, Germany

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TRACERS:

From Description to Quantification

Monika Rhein, IUP Bremen, Germany

C. Böning, J. Bullister, J. Dengg, S. Doney, M. England, R. Fine, T. Haines, S. Khatiwala, D. Kieke, O. Klatt, B. Klein, D. LeBel, J. Lupton, P.Robbins, W.Roether, B.Smethie, D. Smythe-Wright, R. Steinfeldt, R.Well


Formationof Deep and Bottom Water

A New Deep Water Mass in Drake Passage

Ventilation of the Pacific

Tracer ages: what do they tell us?

Conclusion / Outlook


AABW is formed :

western Weddell Sea,

western and eastern Ross Sea,

Adelie Coast,

Amery Ice Shelf


CFC-11 along 0°E,

1984 - 1998

2 deep CFC cores

in AABW

Klatt,Roether,Hoppema,Bulsie

wicz,Fleischmann,Rodehacke,

Fahrbach,Weiss,Bullister,

JGR, 107, 2002


Estimates of AABW Production Rates

WSBW from DWBC transports : 2-5 Sv

WSBW from tracer budgets : 3-5 Sv

AABW from shelf water budgets : 5-15 Sv

AABW from PO4* and C-14 : 15 Sv

Orsi, Johnson,Bullister, 1999, Prog.Oceanogr.43 55-109


AABW - Formation Rate from CFC Inventory

CFC-inventory

[million moles]

Atlantic : 6.2 (1987)

Ind.+Pac. : 4.8 (1993)

Orsi, Johnson,Bullister, 1999, Prog.Oceanogr.43 55-109


Calculation of AABW formation by Orsi et al.

all AABW formation regions treated similar:

-- volume of water sinking across 2500m isobath: V

-- entrainment of ambient water while sinking

-- CFC- Saturation of this mix: 35% (from obs.)

CFC Inventory = V• •  0.35 • C(t) dt + Loss

Atlantic : 4.9 Sv 60%

Indian + Pacific : 3.2 Sv 40%

TOTAL: 8.1-9.4Sv

Orsi, Johnson, Bullister, 1999


AABW Formation and CFCs in Ocean Climate Model

Transient tracers to assess skill of NCAR model

CFC- Inventory. ,AABW

106 moles obs. contr.

---------------------------------------

Atlantic 1987 6.2 1.0 Ind+Pac 1993 4.8 0.6

Sensitivity studies:

A) BBL: Beckmann and Döscher, 1997

B) High_sal: restore S to Smax on shelf and adjacent to it

Doney and Hecht, JPO 32, 2002


Am Ad RS WS

model with BBL

WS: Weddell Sea

RS: Ross Sea

Ad: Adelie Coast

Am: Amery Ice Shelf

CFC

Pt,BBL-Levitus

CFC inventory:

Atl. 1.0 (obs.6.2)

I+P 0.7 (obs.4.8)

S,BBL-Levitus

sig2 BBL-Levitus

0° 90° 180° 270° 0°

Doney and Hecht,2002


High_sal: restore S to

Smax on shelf

Am Ad RS WS

improved AABW-

formation

CFC

CFC-inventory:

Atl. 3.4 (obs 6.2)

I+P 1.4 (obs 4.8)

pT,mod-Lev.

S,mod-Lev

Doney and Hecht,2002

0° 90° 180° 270° 0°


Detection of a new water mass in Drake Passage

1990

He-3 across

Drake Passage

He-anomaly at

2 = 36.95

Ant SAm

1999

Well, Roether, Stevens DSR ,subm.


SPDSW

Southeast Pacific Deep

Slope Water

Well, Roether, Stevens,2002

Lupton, Pyle, Well, Jenkins,

Schlosser, Top, 2002


With OMP analysis:

Fraction SPDSW in %

SPDSW

Drake Passage: 7Sv

(lADCP, CTD)

ANT SA

Well, Roether, Stevens


Formation rates of NADW using CFCs

CFC-inventory LSW 1997:

16.6 million moles

formation rate:4.4-5.6 Sv

low NAO : 1.8- 2.4 Sv

high NAO: 8.1-10.8 Sv

Rhein, Fischer, Smethie, Smythe-Wright, Weiss, Mertens, Min, Fleischmann,

Putzka, JPO, 2002


CFC - inventories and formation rates

of NADW components

1991

1991-inventory formation rate

million mole Sv

uLSW 4.2 2.2

cLSW 14.7 7.4

ISOW 5.0 5.2

DSOW 5.9 2.4

-----------------------------------------------------

total 29.8 17.2 Sv

Smethie and Fine, DSRI, 2001


CFC - inventories and formation rates

of NADW components

1997 cLSW layer CFC-11 inventory

1997 inventory form.rate

million mole Sv

uLSW 7.4 2.6

cLSW 20.5 7.9

ISOW 10.0 7.7

DSOW 8.7 2.4

---------------------------------

total 46.6 20.6

LeBel, Smethie, Andrie, Bullister,

Jones, Min, Rhein, Roether,

Smythe-Wright, Weiss 2002


Modeling CFC inventories and LSW formation rates

CFC observation

1/3° FLAME model

formation rate by

volume change : 4.3Sv

rate from CFC inv: 3.5-4.4Sv

a)

CFC-11

model

Böning, Rhein, Dengg, Dorow,

GRL 2003, accepted

b)


Ventilation of the Pacific from Tracer Ages

CFC-11 along 135°W,1993

1400m

50°N

30°S

Fine, Maillet, Sullivan, Wiley, JGR, 2001


CFC-inventory , 1993, full water column

Bullister, Sonnerup, Fine,

Min, Mecking, Smethie,

Warner, Weiss, 2002


CFC ages on isopycnals

SSM

26.2

STUW

25.0

B

A

NPIW

SAMW

26.8

AAIW

27.2

C

D

Fine, Maillet, Sullivan, Wiley, JGR, 2001


NPIW

SAMW

Bullister et al., 2002


Ventilation flux [Sv] : Volume / mean tracer age

Total Wind driven Thermohaline circ.

 < 26.5 26.5<  <27.3

---------------------------------------------------------------

NP 111 Sv 50% 50%

SP 123 Sv 35% 65%

NP SP

subtrop. gyre 41 Sv 25 Sv agree Sverdrup theory

subpolar gyre 9 Sv 17 Sv

Fine, Maillet, Sullivan, Wiley, JGR, 2001


Ventilation and Mixing of Indian Ocean Waters

Full water column

inventory in 1995:

100 million moles

Fine, Smethie, Bullister, Min, Warner, Rhein, Weiss, DSR, revised, 2002

Poster


Age : time elapsed since last at the surface

-- boundary conditions in source region

-- Mixing : ages are not conservative


Thermocline ventilation in subtropical North Pacific

dc/dt = -v•dc/dy +K•d²c/dy² model with CFCs

ideal age tracer 

d /dt = -v•d/dy +K•d² /dy² +1

10°N NEC 20°N 40°N subp.gyre

outcrop

diffusion advection,diffusion diffusion

Sonnerup,Quay, Bullister, DSR I, 1999


 <15-25years : agree with CFC ages within 25%

older  : tracer ages considerably younger

CFC-11 ages younger than CFC-12

difference increase with age

CFC-11, 12 ages older than ratio ages

Sonnerup, 2001, GRL 28, 1739-1742


Relationship between the ideal age and the tracer age

Co(t) : conc. at surface

G(r,t): age spectrum

C(r,t)=Co(t-t‘) G(r,t‘)dt‘

Holzer and Hall, 2000

G(r,t) dt: mass fraction of fluid at r that was at the

surface at time interval t -- t+dt

1st temporal moment: mean age

2nd temp. moment: width of the age spectrum

Waugh, Hall, Haine, JGR, 2002, subm.


Testing in a GCM

mean age tracer age ideal age

a) 300m

b) 1000m

c) 1500m

Khatiwala, Visbeck, Schlosser, DSR I, 2001


after 200 years integration:

mean ³H-³He ideal

Labrador Sea (1500m) 3.3 3.9 4.0

Subtrop. subduction (500m) 15.8 12.8 21.7

Western Boundary (1500m) 38.4 35.8 56.7

-- tracer ages younger than ideal ages

-- mean age sensitive to long transit time pathways

although they make up only a small fraction

Khatiwala, Visbeck, Schlosser, 2001


use temporal change

of ³H/³He ages to

estimate mixing

a)

b)

Robbins,Price,Owens,

Jenkins, JPO 30, 2000

c)

Isopycnals outcrop north Azores Current: southward

penetration by lateral mixing across AC at 33°N


Relic CFC-11 age, Labrador Sea Water LSW

estimates time scales

of spreading for young

component

age in source region: 15 years

Fine, Rhein, Andrie, GRL,2002, subm.


Future developments

moored tracer sampler


Conclusions

-- CFC inventories: AABW and NADW formation rates

-- ³He signal: new water mass in Drake Passage

-- CFC ages : Ventilation rates of upper and intermediate Pacific

-- ³H/³He age : role of lateral mixing

-- tracers to assess model skills

-- tracer age - ideal age , age spectrum


WOCE Tracer: all sections (concentrations)

isopycnal age distributions,

North and South Atlantic: CFCs, ³H, ³He

www.ocean.uni-bremen.de/en/projects/aims/tab.html

.... /projects/aims/isoage.html

.... /projects/aims_satl/qual.html


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