European Time-series Station ESTOC in the Eastern ...European Time-series Station ESTOC in the...
Transcript of European Time-series Station ESTOC in the Eastern ...European Time-series Station ESTOC in the...
European TimeEuropean Time--series Station series Station ESTOC in the Eastern ESTOC in the Eastern
Subtropical North Atlantic GyreSubtropical North Atlantic Gyre
Susanne Susanne NeuerNeuerArizona State UniversityArizona State University
OCCC Woods Hole 1-4 August, 2005
NASTNAST--WW NASTNAST--EEBATS
The North Atlantic The North Atlantic Subtropical Subtropical GyralGyralProvince (NAST)Province (NAST)
ESTOC
ICCM, ICCM, TeldeTelde, , GranGran CanariaCanaria
BuqueBuque oceanograficooceanografico‘‘TALIARTETALIARTE’’
ICCM, ICCM, TeldeTelde : : Group of Group of OctavioOctavio LlinasLlinasMariaMaria--Jose Jose RuedaRuedaAndres Andres CiancaCiancaFrancisco Francisco LuzardoLuzardoJuana Juana GodoyGodoyMarimarMarimar VillagarciaVillagarciaJavier MarreroJavier MarreroLleireLleire MorotoMorotoRosa MontanaRosa Montana
Univ. Las Palmas:Univ. Las Palmas:Group of Group of MelchorMelchor GonzalezGonzalez--DavilaDavilaMagdalena Magdalena CasianoCasianoLluisLluis LagleraLaglera
Group of Group of Joaquin HernandezJoaquin Hernandez--BritoBrito
IfMIfM Kiel:Kiel:Group of Group of GeroldGerold SiedlerSiedler
Thomas Thomas MMüüllerllerMichaela KnollMichaela KnollUweUwe KoyKoyMarkus Markus BusseBusseJJöörgrg ReppinReppinChristian HaagChristian Haag
Univ. Bremen:Univ. Bremen:Group of Group of GeroldGerold WeferWeferPeer Peer HelmkeHelmkeTim Tim FreudenthalFreudenthalHelgeHelge MeggersMeggersChristina Christina HaynHaynJens LangerJens LangerGGöötztz RuhlandRuhlandVolkerVolker RatmeyerRatmeyer
Support:
German ministry for Research and Education [BMBF]
EU (CANIGO, ANIMATE, MERSEA)Gobierno de CanariasRCOM (DFG), Germany
NASA (EOS) Co-PIs, R. Najjar, D. McGillicuddy
GeoB-Geosciences, University of Bremen; IfM-Institute for Marine Sciences, Kiel; ICCM-Canarian Institute for Marine Sciences, Gran Canaria;IEO-Spanish Institute of Oceanography, Tenerife; ULPGC-University of Las Palmas; UOL-University of Oldenburg; UBOZ-University of Bremen, Tracer Oceanography; UBCH-University of Bremen, Marine Chemistry; AWI-Alfred Wegener Institute, Bremerhaven; ETHZ: Swiss Technical University, Zürich; UHH: University of Hamburg.
Primary Production Upwelling
ESTOCSatellite StudiesICCMGeoB
- a Spanish-Germantime-series station northof the Canary Islands -
Saharan Dust
M o d e l i n g (G
eoB)
Monthly samplingMonthly samplingICCMICCMULPGCULPGC
Process studiesProcess studiesIfMIfM: : HydrographyHydrographyGeoBGeoB: Drifting traps, : Drifting traps, production rates, stableproduction rates, stableisotopes, Foraminiferaisotopes, ForaminiferaUOL: BioUOL: Bio--OpticsOpticsUHH: DOMUHH: DOMETHZ:CoccolithophoridsETHZ:CoccolithophoridsUBOZ: Tracer gasesUBOZ: Tracer gases
Moored particle studiesMoored particle studiesGeoBGeoB: Traps, Camera: Traps, CameraAWI: InfluxAWI: InfluxUBMCH: PumpsUBMCH: Pumps
ExportExportProductionProduction
Moored currentMoored currentmeasurementsmeasurementsIfMIfM
‘‘ExploringExploring--inin--spacespace’…’…..has been the has been the traditional way of ocean exploration sincetraditional way of ocean exploration sincethe first oceanographic expeditions.the first oceanographic expeditions.
But...But...
‘‘ExplorationExploration--inin--timetime’’
Few characteristics of the ocean and the seafloor Few characteristics of the ocean and the seafloor are in steady state, therefore the need is paramount are in steady state, therefore the need is paramount for sustained timefor sustained time--series investigationsseries investigations
Ideally in the combination of hypothesis-testing and development of measurement strategies and new observational tools…in the time domain, not space domain…..
oceanic carbon cycle
Silicifiers N2fixers
DMS producers
CalcifiersNano
phytoplankton
Fe NO3Si
CaCO3
DMSPO4 NH4
DOM
biological carbon pump
4944
4.5
CO2
CO2 + H2O (H2CO) +O2
Photosynthesis
90 1.8
0.5
5
PgC/yPgC/y
ExportExport
Modified after Corinne Le Queré
ESTOC
Hypothesis 1: Dust input influences primary Hypothesis 1: Dust input influences primary and export productionand export production
Hypothesis 2: Export ratio scales with input Hypothesis 2: Export ratio scales with input of of ‘‘newnew’’ nutrientsnutrients
ESTOC
The physical context and biogeochemistryThe physical context and biogeochemistry
ESTOC is located in the eastern boundary current region of ESTOC is located in the eastern boundary current region of the subtropical NA Gyrethe subtropical NA Gyre
a b
c d
Seasonal geostrophic transports for upper few hundreds meters along 29° NMichaela Knoll in John et al., 2004
Typical of a subtropical gyre station
Winter mixed layer from around 20 m in summer to up to 150 m in winter
Nitrate not measurable in upper mixed layer with standard methods
Phytoplankton biomass maximum in winter follows the break-up of the seasonal thermocline in late fall
Chlorophyll levels in winter are usually around 0.4 mg l-1, and in summer around 0.05 mg l-1 in the surface
Seasonal cycle at ESTOC TT
NONO33
ChlChl
Neuer et al, in prep.
-200
-150
-100
-50
0P
ress
ure
(dba
r)
0 0.1 0.2 0.3 0.4 0.5
1994 1995 1996 1997 1998 1999 2000
Chlorophyl a (µg/l)
Chlorophyll peaks during time of deepest mixing in winter.
Neuer et al, in prep.
Chlorophyll peaks during time of deepest mixing in winter.
Neuer et al, in prep.
Particle flux maxima in late winter following the maxima of chlorophyll and primary productivity
Strong interannualvariability concomitant with the variability in mixing depth
Yearly integrated primary production at ESTOC = 12 mol C m-2
yr-1 and integrated particulate C-export = 0.2 mol C m-2 yr-1
Particle flux and its relationship to surface water processes
Jan Jul Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec
0
40
80
120
Tota
l Flu
x
( mg
m-2
d-1 )
0.5 km1 km
Jan Jul Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec
18
22S
ST
(C)
Jan Jul Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec
0
0.2
0.4
0.6
0.8
Sur
face
chl
orop
hyll
(mg
m-3
)
Prim
ary
Prod
uctio
n (m
g m
-2d-1
)
ChlPP
1994 1995 1996 1997 1998 1999 2000
Jan Jul Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec Jun Dec
-1.6-1.2-0.8-0.4
00.40.8
Biol
C u
ptak
e (m
mol
m-2d-1
)
Neuer et al. in prepNeuer et al., in prep.
Seasonal and interannual variability in the carbon dioxide species
CT biol. calculated as difference between total NCtchange and contribution from air sea exchange and mixing.
1. Jan-March Increase of CT due to winter convection2. March-October:
CT decrease due to biol. productivity + outgassing
CT(biol) ranges between 2-4 mol/m2/yr Gonzalez-Davila et al., GBC, 2003
∆CT (total inorganic carbon) variation as difference between 2 months
Gonzalez-Davila et al. , GBC, 2003
Net CO2 fluxes at ESTOC are positive with an average value of 0.05 mol CO2 m-2 yr –1
p CO2 increases at a rate of 1.2 ± 0.3 µatm/yr
pH decreases 0.001 units/yr
CT increases at 0.9 ±0.2 µmol/kg/yr
Gonzalez-Davila et al. , GBC, 2003Neuer et al. in prep.
Seasonal and interannual variability in the carbon dioxide species
ESTOC
Hypothesis 1: Dust input influences export Hypothesis 1: Dust input influences export productionproduction
ESTOC
Hypothesis 1: Hypothesis 1: Dust input influences export productionDust input influences export production
ESTOC
Jan Apr Jul Oct Jan Apr Jul Oct Jan
0
20
40
60
80
100
Tota
l flu
x (m
g m
-2d-1
)1997 1998
0
200
400
600
800
Dust conc (µg m
-3 )
C
D
Particle fluxes at ESTOC and dust deposition determined at Gran Canaria
Neuer et al., GBC, 2004
Dust
Flux
SST MLD
ChlN-input
Neuer et al (in press, GBC)
Jan Apr Jul Oct Jan Apr Jul Oct Jan
0
40
80
120
160
200
Dus
t con
c (µ
g m
-3 )
Tota
l Flu
x (m
g m
-2d-1
)
Jan Apr Jul Oct Jan Apr Jul Oct Jan
0
40
80
120
160
200
Dus
t con
c (µ
g m
-3 )
Tota
l Flu
x (m
g m
-2d-1
)
+14 days
Do peaks in dust fluxes and traps coincide?
At ESTOC winter particle fluxes coincide with(or follow with a short lag) dust deposition
Neuer et al., GBC, 2004
OK, there is a coupling, but does that imply a causal relationship?
Rates (g m-2, Jan-March)
1997 1998
Aeolian deposition1… 3.3 8.1
Primary production2 38 33
0.76Export production3
(C org, 150 m)
1assuming mean deposition rate of 1 cm s-1 (Torres-Padrón et al. 2002); 2 Neuer et al., 2002; 3normalized to 150m (Martin et al., 1987, open ocean composite).
0.73
Dust derived N deposition (wet and dry) amounts to 4-6% of new nitrogen need at ESTOC (on an annual basis).
So, what about iron?So, what about iron?
1Torres-Padrón et al. 2002, 2 assuming Fe-content of 3.5% WT (Duce 1986); 3assuming a solubility index range of 1-10% (Fung et al. 2000); 4primary production of 12 mol C m-2 yr-1(Neuer et al. 2002) and Fe:C ratio of 10 µmol/mol (Sunda and Huntsman 1995, 1997)
Fluxes 1997 1998
Dust deposition 1
(g m-2 yr-1 )11 29
Total Fe-deposition2
(g m-2 yr-1 ) 0.38 1.03
Soluble Fe-deposition3
(mmol m-2 yr-1 )0.07-0.7 0.18-1.8
Total Fe-assimilation4
(µmol m-2 yr-1 )
Supplied/Assimilated
113 116
0.6 1.6
Iron:Highly episodic nature of dust deposition might impose feast-famine situation on the phytoplankton and eolic iron deposition may relief iron stress in winter when phytoplankton biomass is high (which might explain some of the observed temporal coupling in winter).
But: What about N2-fixation?
DIN/DIP is at Redfield ratio at ESTOC, but elevated at BATS. There is no indication of significant N2 fixation at ESTOC, i.e., stimulation by iron not relevant.
0.0 0.2 0.4 0.6 0.8Phosphate (µM)
0
2
4
6
8
10
Nitr
ate-
N (µ
M)
ESTOCBATS
Neuer et al., GRL, 2002
Winter
Summer
Jan Apr Jul Oct Jan Apr Jul Oct Jan
0
200
400
600
800
1000
Dus
t con
c (µ
g m
-3 )
Jan Apr Jul Oct Jan Apr Jul Oct Jan
0
1
2
3
Opa
l flu
x ( m
g m
-2 d-1
)
0
10
20
30
40
50
Carbonate flux ( m
g m-2 d
-1)
OK, no (major) enhancement of (new) production, what about a response on the organisms level?
Opal
Carbonate
Dust
Carbonate sedimentation is higher by a factor of Carbonate sedimentation is higher by a factor of 1.4, similar to the enhancement of 1.4, similar to the enhancement of lithogeniclithogenic
matter, in winter 1998matter, in winter 1998
Rates (g m-2, Jan-March)
1997 1998
Aeolian deposition 1… 3.3 8.1
Primary production2 38 33
Trap fluxes3
Lithogenic matter 0.94 1.4
Corg 3 0.73 0.76
Opal 0.08 0.07
Carbonate 1.6 2.3
1assuming mean deposition rate of 1 ms-1 (Torres-Padrón et al. 2002); 2 Neuer et al., 2002; 3 Corg: normalized to 150m (Martin et al., 1987, open ocean composite).
LithogenicCorgOpalCarbonate
LithogenicCorgOpalCarbonate
0.97
0.73
1.6
0.08
lithogenics15
Ballast: Despite the high lithogenic matter loading of sinking particles, carbonate is the main ballasting agent
2.65 g cm-32.71 g cm-3Density?
ESTOC
Hypothesis 1: Dust input influences Hypothesis 1: Dust input influences primary and export productionprimary and export production(nutrients, ballasting).(nutrients, ballasting).
Little influence on primary and export Little influence on primary and export production production
Feast/famine situation imposed by Feast/famine situation imposed by highly episodic iron highly episodic iron
Ballasting effect: rather smallBallasting effect: rather small
ESTOC
Hypothesis 2: Export ratio scales Hypothesis 2: Export ratio scales with input of with input of ‘‘newnew’’ nutrientsnutrients
0.2
0.4
0.6
0.8
1.0
Prim
ary
Prod
uctio
n
( g m
-2 d-1
)0.0
0.2
0.4
Surf
ace
chlo
roph
yll
( mg
m-3
)
A
B
1996 1997 1998
Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct0
20
40
60
E-PO
C
(mg
m-2d-1
)
ESTOC MTESTOC STBATS
Seasonality of surface chlorophyll, integrated primary productionand export production at ESTOC and BATS
Chl a
PP
Epoc
Neuer et al., GRL, 2002
Yearly integrated PP, E POC and ER (EPoc /PP) for ESTOC and BATS
PPmol C m-2 yr-1
E POCmol C m-2 yr-1
ER
BATS ESTOC BATS ESTOCa BATS ESTOCb
1996 16.3 11.9 1.4 0.24 / 0.16 0.086 0.017
1997 13.3 12.0 1.3 0.16 / 0.16 0.098 0.013
1998 13.9 11.7 0.7 -- / 0.20 0.050 0.017
AVG 14.5 11.9 1.1 0.2 0.08 0.016aShallow moored/surface tethered trap. Surface tethered trap value of 1996 and 1997composite of both years b Mean of moored and surface tethered traps.
Neuer et al., GRL, 2002
What we would expect…
When averaged over appropriate spatial When averaged over appropriate spatial and temporal scales, new production is and temporal scales, new production is equal to export production.equal to export production.
Thus, under steadyThus, under steady--state conditions, one state conditions, one would expect the ratio of new to total would expect the ratio of new to total production (production (ff--ratio) to be equivalent to the ratio) to be equivalent to the export ratio (ER)export ratio (ER)
What does that mean…
Does a lower ER at ESTOC also imply lower Does a lower ER at ESTOC also imply lower input of new nutrients into the mixed layer input of new nutrients into the mixed layer compared to BATS?compared to BATS?
Three main sources of new nutrients: Three main sources of new nutrients: Wintertime convective mixingWintertime convective mixingMesoscaleMesoscale eddieseddiesNitrogen fixationNitrogen fixation
Mixed layer depth and Nitrate-N input at ESTOC and BATS
Cianca et al., in prep.
0
100
200
300
400
Nitr
ate-
N (m
mol
m-2
)
250
200
150
100
50
0
Mix
ed la
yer d
epth
(m)
1994 1995 1996 1997 1998 1999 2000
--- Mixed layer___ Nitrate-N
0
100
200
300
400
Nitr
ate-
N (m
mol
m-2
)
400
300
200
100
0
Mix
ed la
yer d
epth
(m)
1994 1995 1996 1997 1998 1999 2000
--- Mixed layer___ Nitrate-N
ESTOC
BATS
New Production based on nitrate draw down and mesoscale eddy
Activity at ESTOC and BATS
0.12 0.12 0.070.07-- 0.20.2BATSBATS
0.02 0.02 0.03 0.03 -- 0.20.2ESTOCESTOC
EddyEddy--inducedinducednitrate nitrate inputinputaa
(mol N/m2/yr)(mol N/m2/yr)
NitrateNitratedraw downdraw down(mol N/m2/yr)(mol N/m2/yr)
What does that mean…
Does a lower ER at ESTOC also imply lower Does a lower ER at ESTOC also imply lower input of new nutrients into the mixed layer input of new nutrients into the mixed layer compared to BATS?compared to BATS?
Three main sources of new nutrients: Three main sources of new nutrients: Wintertime convective mixingWintertime convective mixingMesoscaleMesoscale eddieseddiesNitrogen fixationNitrogen fixation
Snapshots of temperature and new production in a 0.1 degree resolution simulation of the North Atlantic (McGillicuddy et al., GBC, 2004)
New Production based on nitrate draw down and mesoscale eddy
Activity at ESTOC and BATS
0.12 0.12 0.070.07-- 0.20.2BATSBATS
0.020.020.03 0.03 -- 0.20.2ESTOCESTOC
EddyEddy--inducedinducednitrate nitrate inputinputaa
(mol N/m2/yr)(mol N/m2/yr)
NitrateNitratedraw downdraw down(mol N/m2/yr)(mol N/m2/yr)
ESTOCHypothesis 2: Export ratio scales Hypothesis 2: Export ratio scales with input of with input of ‘‘newnew’’ nutrientsnutrients
Yes, low export production at ESTOC is accompanied by a lower input of new nutrients compared to BATS (by mesoscalemesoscale eddy activity and nitrogen eddy activity and nitrogen fixationfixation)
AND: Lower input of new nutrients does not Lower input of new nutrients does not necessarily result in lower PP (or biomass) but necessarily result in lower PP (or biomass) but influences the removal efficiency (export influences the removal efficiency (export ratio) of biologically produced carbon into the ratio) of biologically produced carbon into the oceanocean’’s interior.s interior.
Conclusions
Especially by inter site comparisons can we learn Especially by inter site comparisons can we learn and test hypotheses on biogeochemical processes and test hypotheses on biogeochemical processes on a global scale and on multion a global scale and on multi--year time scales.year time scales.
TimeTime--series station ESTOC enables a view into series station ESTOC enables a view into ““the other sidethe other side”” of the subtropical of the subtropical NAtlanticNAtlanticgyre (which is different)gyre (which is different)
Andrés Cianca:
BATS and ESTOC: A comparison between Western and Eastern parts of the Subtropical
Atlantic Ocean
Peer Helmke:
Vanished without a trace: sedimentation pulses in the deep sea, can we
determine their origin?
NASA-EOS