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Water mass structure in the South Water mass structure in the South Atlantic and its decadal variabilityAtlantic and its decadal variability
Demidov A.N., Krayushkin E.V., Demidov A.N., Krayushkin E.V., Kalashnikova N.A., Chereshnuk S.A.Kalashnikova N.A., Chereshnuk S.A.
Moscow State Universitytuda@mail.ru
••
Main goalMain goal: : determine South Atlantic water mass determine South Atlantic water mass structure and its longstructure and its long‐‐term variability.term variability.
•• TheThe
key objectskey objects
of the investigation are the Antarctic of the investigation are the Antarctic
Intermediate and Bottom Waters (AAIW and AABW) and Intermediate and Bottom Waters (AAIW and AABW) and the components of the North Atlantic Deep Waters the components of the North Atlantic Deep Waters
(NADW)(NADW)
TasksTasks••
Determination of water mass structure and boundariesDetermination of water mass structure and boundaries
•• Analysis average characteristics in the transatlantic Analysis average characteristics in the transatlantic
sectionssections
Water mass structure of the Atlantic oceanWater mass structure of the Atlantic oceanAAIW – Antarctic Intermediate WatersNADW – North Atlantic Deep Waters
UNADW – Upper NADWMNADW – Middle NADWLNADW– Lower NADW
MIW – Mediterranean Waters ISOW – Iceland-Shetland Overflow WatersLSW – Labrador Sea WatersDSOW – Denmark Strait Overflow Waters
UCPW – Upper Circumpolar WatersAABW – Antarctic Bottom WatersLCPW – Lower Circumpolar Waters
WSDW- Weddell Sea Deep Waters
*Black lines are the boundaries of waters according to location of maximal vertical salinity gradient
UCPW
How NADW components relate to water mass of the North How NADW components relate to water mass of the North Atlantic?Atlantic?What do bottom waters to the north from the Argentine What do bottom waters to the north from the Argentine basin consist of? What proportion of WSDW and LCPW is basin consist of? What proportion of WSDW and LCPW is presentpresent
in them?in them?
Wust, 1936; CFC fromMolinari et al., 1990
Rhein et al., 1995; Vanicek, Siedler, 2002
max min max min
UNADW S,CFC SUNADW T,S,
CFC Si,P
MNADW O2 CFCLSW O2
LNADW-old O2 , CFC
LNADW O2 ,CFC OLNADW O2 ,
CFC
Wust, 1936
Tsuchiya et al., 1992
Rhein et al., 1995
Schmitz, 1996
Andrie et al. 1998
UNADWMIW MIW+
LSWUpper LSW LSW+
MIWLSW
MNADWLSW ISOW+
EBW+DSOW
LSW+ISOW
DSOW, ISOW, AABW
CPW+LSW+ISOW
LNADW DSOW AABW+DSOW
DSOW DSOW, ISOW, AABW
DSOW
North Atlantic Deep North Atlantic Deep Water components. Water components. Classification and Classification and originorigin
Location of the Location of the maximal vertical maximal vertical gradients of the gradients of the different different characteristics and characteristics and water mass structure water mass structure at the A17 sectionat the A17 section
Max grad.TSO2SiPCFC
AAIW
UCPWUNADW
MNADW
LNADW
AABW AABW
NS
Max grad.TS
∆S
∆θ
Difference of water mass Difference of water mass structure, temperature and structure, temperature and salinity between 2003 and 1994 salinity between 2003 and 1994 A17 sections. A17 sections. Solid line marked 1994 data, Solid line marked 1994 data, dashed 2003. dashed 2003. Blue line Blue line ––
location location of maximal vertical temperature of maximal vertical temperature gradient, black gradient, black --
salinitysalinity
Run 1:
500-2000 m MIW, LSW, AAIW, WNACW –
2
Run 2: below 1500 mLSW,ISOW,DSOW,MIW,AABW
Run 3:
below 2500m LCPW, WSDW, NADW, SPDW
Bottle data of WOCE Sections –
initial data for OMP analysis
Extended Optimum Multiparameter AnalysisExtended Optimum Multiparameter Analysis
OMP package for Matlab by Karstensen, Tomczak, 1999
Source water typesSource water types
TT SS OO22 SiSi NONO33 POPO44
AAIW 4.00 34.21 5.84 18.89 28.40 1.91
MIW 11.11 36.30 4.34 8.66 16.20 1.12
LSW 3.08 34.86 6.88 9.08 16.53 1.06
ISOW 2.92 35.00 6.33 10.20 16.00 1.04
DSOW 0.25 34.93 7.05 7.91 12.09 0.91
NADW 3.02 34.95 6.35 14.11 17.68 1.16
AABW (WSDW) -0.74 34.65 5.90 114.8 31.38 2.07
uWNACW 18.90 36.60 4.72 2.00 6.00 0.25
lWNACW 9.40 35.10 4.06 15.00 24.00 1.70
SPDW 2.02 34.67 3.90 100.5 34.70 2.39
UCPW 2.50 34.60 4.60 70.00 29.00 2.20
LCPW 0.92 34.72 4.65 113.6 31.07 2.29
Source water types from WOA09
OMP Result OMP Result Run 1Run 1: A20: A20MIW, LSW, AAIW, WNACWBlack line –
water mass boundaries
%LSW
%AAIW
WNACW AAIW
UNADWLSW
WNACW AAIW
UNADWLSW
OMP Result OMP Result Run 1Run 1: A20: A20MIW, LSW, AAIW, WNACW
%MIW
%WNACW
WNACW AAIW
UNADWLSW
WNACW AAIW
UNADWLSW
OMP Result OMP Result Run 2Run 2: A06: A06LSW,ISOW,DSOW,MIW,AABW
%LSW
%ISOW
WB EB
UNADW
MNADW
LNADW AABW
UNADW
MNADW
LNADW AABW
WB EB
OMP Result OMP Result Run 2Run 2: A06: A06LSW,ISOW,DSOW,MIW,AABW
%DSOW
%AABW
WB EB
UNADW
MNADWLNADW
AABW
UNADW
MNADW
LNADW AABW
Eq. Ch. Brazil Basin Vema Ch. Arg. B.
Eq. Ch. Brazil Basin Vema Ch. Arg. B.
OMP Result OMP Result Run 3Run 3: A17: A17LCPW, WSDW, NADW, SPDW without Si
% WSDW% WSDW
% LCPW% LCPW
LNADW
LNADWMNADW
MNADW
80 60 40 20 0 20 40 606000
5000
4000
3000
2000
1000
0
80-40 %10-40 %
30-50 %70-45 %
0 - 5 %
50-60 %20 %10 %
20-10 %
10 %50-60 %10-20 %20-10 %
10-20 %
10-5 %20-40 %
70-55 %
10-20 %
10-30 %80-50 %
10-20 %
10-30 %
10-20 %70-30 %
60-40 %40-60 %
10-5 %20-40 %
60-40 %40-60 %
10-50 %
80-65 %
80-30 %10-20 %
10-20 %60-20 %
10 %20-40 %
40-60%60-40%
60-40%40-60%
10-40%
0-10%
10-20%
80-30%
MIW AAIW
+ UCPW
SPDW
LCPW
UNADW
MNADW
LNADW
NA
DW
LSW
ISOW
DSOW WNACW
AABW WSD
W
70-
55 %
40-55 %0-5 %
60-40 %
40-55 %0-5 %
60-40 %
0-20 %60 %
40-20 %
(EBW)
Dep
th
N S
All OMP Runs results schemeAll OMP Runs results scheme
Latitude
This work max min The main originUNADW S,CFC P, Si LSW, AAIW, MIWMNADW O2, P CFC ISOW, LSW, EBWLNADW O2 ,CFC P ISOW, AABW, DSOW
Origin of the NADW componentsOrigin of the NADW components
NADW components pathwaysNADW components pathways
[Morozov,Demidov et al.,2010]
Vema channelVema channel
Equatorial channelEquatorial channel
Potential temperature Potential temperature temporal variability temporal variability near bottom in the near bottom in the Vema and Equatorial Vema and Equatorial channels (minimal at channels (minimal at the each section).the each section).
map
ºC
ºC
LongLong--term variabilityterm variability
AABWAABW
AABW temporal and AABW temporal and spatial variability in spatial variability in the Vema Channelthe Vema Channel
Bot.θ,S
From Morozov, Demidov et al., Springer, 2010
θ
Stations along Vema Channel
Example of difference between Example of difference between 2009 and 1983 sections at the 242009 and 1983 sections at the 24ººSS
Computing average values. We used γn
approximation of the maximal vertical gradients position
∆S
∆θ
AAIW NADW
AABW
Temporal Temporal θθ,S variability of water mass ,S variability of water mass in DWBCin DWBC88--1111
S S ––
dashed, 24 S dashed, 24 S ––
solid, black horizontal line solid, black horizontal line ––
climate (Gouretsky, Koltermann)climate (Gouretsky, Koltermann)
θ
S
AAIW NADW
AABW
Integral temporal Integral temporal θθ,S variability of water mass at the sections,S variability of water mass at the sections88--1111
S S ––
dashed, 24 S dashed, 24 S ––
solid, black horizontal line solid, black horizontal line ––
climate (Gouretsky, Koltermann)climate (Gouretsky, Koltermann)
θ
S
11 S
11 S
11S
Conclusion••
Due to results of OMP analysis it is established that Due to results of OMP analysis it is established that NADW the South Atlantic consist mainly of ISOW and NADW the South Atlantic consist mainly of ISOW and LSWLSW
••
The Antarctic waters in the bottom layer in the Brazil The Antarctic waters in the bottom layer in the Brazil basin have LCPW share, approximately exceeding basin have LCPW share, approximately exceeding WSDW 2 timesWSDW 2 times
••
MNADW probably propagated from the eastern basin. MNADW probably propagated from the eastern basin. MNADW penetrates into the western basin through MNADW penetrates into the western basin through MAR only to the south of 20 NMAR only to the south of 20 N
••
In the Southern Atlantic we observed the cooling and In the Southern Atlantic we observed the cooling and desalination tendency of water mass below the surface desalination tendency of water mass below the surface layer (especially AAIW and AABW), that is in a good layer (especially AAIW and AABW), that is in a good agreement with results of [Levitus et al., 2005]agreement with results of [Levitus et al., 2005]
Thank you for your attentionThank you for your attention