Download Time Series Particle Fluxes from the Iceland Sea: 1986 to...

Time Series Particle Fluxes from the Iceland Sea: 1986 to Present
Jon Olafsson ([email protected], Marine Research Institute)
Dorinda Ostermann ([email protected]), William B. Curry, Susumu Honjo, Steven J. Manganini ([email protected])(W.H.O.I., Woods Hole, MA 02543)
Labrador
Sea
Norwegian
Sea
R
RE
N
T
NEWFOUNDLAND
CU
50
˚N
W
OR
N
NO
RT
H
AT
LA
40
N T I C C U RR E N
˚N
T
E
A
GI
N
60˚N
IRELAND
Modified from McCartney et al., 1996. Oceanus, vol. 39(2).
particle fluxes in mg/m2/day, col-
99
lected by sediment traps in the Ice-
96
3
94
93
and variable fluxes collected from
92
91
1998
1987 to 1986; the highlighted 1997
bell curve flux; the large flux in400.00
70°N
95
1987-present. Note: the sporadic
90
89
crease in 1998, and the beginning
88
of the 1999 particle flux.
87
40
30
2
NB
70°
IP
1
Iceland
GBN
GBS
IP
IP
BI
LB
NS
60°
1999
20°W
A comparison of the deep ocean particle fluxes (total <1mm and C-org annual fluxes) col-
influenced areas.
Lofoton Basin and Norwegian Sea) with the Iceland Sea particle fluxes of
1986-1997 average and the 1998 flux.
Nordic Sea Component Flux
100
Note the similar fluxes in the Iceland Sea 1986-1998 average fluxes with
100.00
0.00
Feb
Mar
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
the arctic influenced Nordic Sea and the 1998 Iceland Sea flux with the At-
90
lantic influenced Nordic Sea region.
80
a.) Nordic Sea total <1mm annual fluxes g/m2/yr (histogram) and C-organic
70
annual fluxes in g/m2/yr (lines).
Dec
month
0.2
b
C-inorg.
C-org.
50
40
30
Salinity deviation
0
-1
0.1
1960
1970
1980
1990
2000
20
Iceland Sea Particle Fluxes
0.0
-0.1
10
-2
FS
-0.3
1988) to 215 mg m-2 day-1 (Aug. 1989). The annual average total particle flux of 5.6 g m-2 yr-1 ranged from 1.4 g m-2 yr-1 (1988) to 9.9 g m-2 yr-1 (1997) and was dominated by biogenic components consisting of an average
1970
1980
1990
2000
-2
-2
IP
Nordic Sea Particle Flux Mole Ratios
Corg/C-inorg.
Si-Bio/C-inorg.
3
Mole Ratio
Other explanations are required to explain the 1998 particle flux in the Iceland Sea. Continued collection of particulate fluxes are necessary to determine if this will be a reoccurring condition or a single event. As can
Nordic Sea Particle Fluxes
2
1
The annual Iceland Sea particle fluxes for the years 1987-1997 and 1998 have been compared to several time series sediment trap particle fluxes in the Nordic Sea. We find a dramatic difference between deep ocean
total particulate fluxes in areas influenced by Atlantic waters, and fluxes collected in areas influenced by polar waters. The average annual Iceland Sea particle fluxes for the years 1987-1997 are similar in amount to the
Advection of Atlantic Water through the Greenland Strait into the Iceland Sea is connected to the regional meteorologic condition as pro-
0
polar influenced fluxes of the Fram St. and Greenland Basin, whereas the Iceland Sea 1998 annual particle flux is similar to the Atlantic influenced sites of the Norwegian Sea and Bear Island and Lofoton Basin areas. This
posed by Unnsteinn Stefansson.
FS
GB
GB
IP
Global Perspective
The mid-latitude meridional atmospheric pressure gradient variations described by the NAO index, do not explain the observed hydrographic
c.) Nordic Sea annual flux moles ratios C-org./C-inorg. And Si-
tic region results in the reduced delivery of particles to the deep ocean when compared to the polar regions of the Southern Ocean and the North Pacific. The biological pump of the Arctic is also dissimilar to the polar regions
bio/C-inorg.
of the Southern Ocean and North Pacific in that the relative amount of Biogenic Si is also reduced.
Annual particle fluxes in the Iceland Sea appear to switch from low delivery of biogenic particles to the deep sea to a very high delivery of biogenic particles to the deep sea. Conditions altering the Polar regions not only
NAO winter
indices for winter (Dec.-Mar).
89
90
91
93
Year
94
97
98
the 1998
IP 86-97
years
IP 1998
n
a
n
In
dia
S
Se
S
ia
ab
S
66
SO
S
63
56
60
SO
SO
SO
PA a
C
9N
PA
C
PA eq
C
12
S
Ar
EQ
EQ
EQ
a
sk
Se
ot
Pa
p
g
kh
O
rin
Be
N
2S
AT
N
34
2N
EQ
48
E
E
AB
EQ
N
AB
n
a
ia
Se
n
ia
Ar
ab
In
d
SO S
63
S
SO
66
S
S
60
56
SO
SO
k
Pa
p
PA a
C
9N
PA
EQ C
PA eq
C
12
S
EQ
EQ
ts
a
O
kh
o
Se
g
rin
Be
S
N
48
AB N
E
3
EQ 4N
AT
EQ 2N
AT
2S
N
AB
E
BI
LB
B
IP
IP
G
Location
n
a
dia
Se
n
ia
In
S
S
63
66
SO
SO
S
60
SO
56
S
0
SO
0
87
AT
S
BI
N
IP
LB
IP
B
G
B
B
FS
C
G
N
org./C-inorg. And Si-bio/C-inorg.
elemental analysis is available, and
0.00
ab
6
Ar
4
Pa
p
PA a
C
9N
PA
C
e
q
PA
C
12
S
2
EQ
0
f.) Global Ocean annual flux moles ratios C-
bio/C-inorg. for the 7 years where
1.00
c.)Connections between salinity deviations at the Siglunes section and the NAO
-2
C-organic) =100%
moles ratios C-org./C-inorg. And Si-
EQ
Siglunes section and mean (S+SE)-(N+NW) wind frequencies.
5
inorganic)+(moles of Si-biogenic)+ (moles of
1
EQ
f) Iceland Sea average annual flux
a. and b.)Connections between temperature and salinity deviations at the
69
centration calculated as; (moles of C-
able, and the 1998
ot
sk
where elemental analysis is avail3.00
fluxes in g/m2/yr (lines).
e.) Global Ocean annual fluxes in mole% con-
10
kh
ganic) =100% for the 7 years
m2/yr (histogram) and C-organic annual
2
of Si-biogenic)+ (moles of C-or4.00
f
d.) Global Ocean total <1mm annual fluxes g/
as; (moles of C-inorganic)+(moles
5.00
a
Si/Ci
Se
68
70
f
Corg/C-inorg.
Si-Bio/C-inorg.
in mole% concentration calculated
Co/Ci
c
Global Particulate Flux
15
Corg/C-inorg.
Si-Bio/C-inorg.
g
Iceland Sea Mole Ratios
6.00
Iceland Sea Mole Ratios
3
e) Iceland Sea average annual fluxes
in
the 1998
98
O
97
Be
r
94
2S
93
Year
2N
91
2.00
-0.3
-4
Total <1mm Flux g/m2/yr
N
90
AT
65 79
89
Location
Bodungen, Geol Rundch (1995) 84:11-27
EQ
-0.2
87
IP 1998
years
AT
67
IP 86-97
S
possible.
0%
60°
N
75
0°
N
71
60°
N
77
120°
Sediment trap samples from the Parflux Lab, and GB and NS data from B.von
0%
0%
rectly due to relatively high nutri-
therefore maintain favorable mixing conditions and make a longer lasting plant production
95
180°
34
90
82
88
120°
emental analysis is available, and
tension of drift ice and consequently small or even negligible admixture of polar water to
83
98
in g/m2/yr for the 7 years where el-
the surface layers, continued inflow of Atlantic water to the North Icelandic Sea should
97
-0.1
10%
48
89
76
78
96
0.0
10%
lantic water than in the highly stratified Arctic water. During warm periods with small ex-
81
72
the North Icelandic area, both di-
20%
d) Iceland Sea average annual fluxes
E
87
58
56
an important nutrient source to
20%
ticle flux collected in 1998
E
63
20%
AB
0.1
60°
30%
40%
30%
because of much more efficient renewal in the surface layer by eddy diffusion in the At93 92
73 94
AESOPS
60°
40%
1997, compared to the annual par-
the Atlantic water inflow provides
40%
50%
AB
66
60%
N
0.2
50%
ent concentrations and indirectly
60
52
54
80
91 57
86
74
84
53
ticulate fluxes for the years 1987-
N
ished nutrients.
61
the warm years. On the contrary,
Iceland Sea average annual par-
60%
LB
Atlantic water advection onto the North Iceland
e.)In 1980 the strong Atlantic water inflow replen-
greater in the cold years than in
70%
60%
BI
20
0.4
59
85
30°
IP
10
(S+SE)-(N+NW) wind frequency %
62
30°
IP
d.)The spring of 1979 was cold and with very little
55
64
CaCO3
C-org.
e
B
ing years 1979 and 1980.
69
c
b
Si-Bio
B
80%
C-org.
Si-Bio
C-inorg.
e
90%
SiO2
80%
G
earlier than in the warmer years.
EqPac
100%
C-org
0°
B
70
0
C-inorg.
Arabian
Sea
0°
Iceland Sea Mole % Normalized
G
The surface distribution of Nitrate in two contrast-
-10
100%
years
98
Iceland Sea Particle Flux Mole concentration
90%
the annual production will be
-0.3
-0.4
-20
97
100%
have occurred about one month
This does not however imply that
68
79 65
94
Global Particulate flux
30°
B
-0.2
30°
0
IP 1998
70%
82
98
77 71 75
88
67
0
80%
97
90
95
inorg.
year
of the spring bloom appears to
83
-0.1
93
Location
H
0.0
81
91
P
1
NABE
5
FS
0.1
90
0
C
73
89
0
60°
BS
94
89
58
87
1
10
N
0.2
10
tios C-org./C-inorg. And Si-bio/C-
IP 86-97
the period 1970-1980 the onset
80
59
64
57 85
91
86 93
92
74
66
87
84
63
72 56
76
78
96
%mole flux normalized to 100%
62
60°
Bering
Sea
0
Mole Ratio
b
c) Iceland Sea annual flux moles ra-
5
face layer of the coldest years of
61
60
1
★
Sea of
Okhotsk
15
ganic) =100%
10
cause of strong stability in the sur-
0.4
0.3
(1984) has suggested that be-
20
B
★
of Si-biogenic)+ (moles of C-or15
2
25
2
20
FS
e
as; (moles of C-inorganic)+(moles
20
30
75°
C
(S+SE)-(N+NW) wind frequency %
mole% concentration calculated
25
Nordic
Sea
75°
G
20
35
b) Iceland Sea annual fluxes in
3
40
C
10
a
I0EB
2
4
50
H
0
C-org
d
60
BS
-10
60°
40
emental analysis is available.
30
warm and cold years Thordardottir
0°
N
water. On the basis of data from
95
-3
-20
60°
BS
H
67
120°
N
area and/or the admixture of Polar
71
180°
C
the influx of Atlantic water to that
CaCO3
30
120°
3
Mole % Normalized
area seems to depend largely on
82
81
75
m2/yr for the 8 years where el-
SiO2
35
Iceland Sea Particle Flux
45
Total Flux
C-org
spring in the area North of Iceland
84
Yearly flux g/m2/yr
89
68
a) Iceland Sea annual fluxes in g/
Lith
5
Mole Ratio
92 91
93
86 63
66
97
Iceland Sea Component Yearly Flux
40
C
76
58
d
70
The onset of nutrient uptake in
96
6
Total Flux
C-org Flux
80
C-org. Flux g/m2/yr
72
94
★
Mole % normalized
73
62
d
6059
64
61
56
57 80 74
87
7885
Nutrient input
North of Iceland
Mole Ratio
a
2
Global Particulate Flux
90
influence atmospheric and the surface ocean but also will influence the deep ocean.
Total Flux <1mm g/m2/yr
3
79
69
NS
as; (moles of C-inorganic)+(moles of Si-biogenic)+ (moles of
As a Global framework, annual particle deep ocean fluxes collected from the Arctic regions are the smallest of all the oceans and are comparable to the South Pacific gyre (EQPAC 12S). The biological pump in the Arc-
variations North of Iceland.
-2
LB
C-organic) =100%
local wind direction variations is short, on the order of a few months.
88
70
8390
BI
b.) Nordic Sea annual fluxes in mole% concentration calculated
tions, possibly by affecting the amount of polar water that is advected eastward from the East Greenland Current. The ocean response time to
-1
IP
Location
may indicate a possible connection of the 1998 particle fluxes with the Atlantic and Polar influence on the biogeochemical processes in the Iceland Sea.
The north-south wind regime northwest and west of Iceland, in January through May has a strong influence on the Atlantic water advection
and resultant hydrographic conditions in late May and early June. The east-west leaning of the wind additionally relates to the salinity varia-
77
98
NS
-1
been seen in the Iceland Sea Particle Flux early 1999 increased fluxes indicate that it will continue into the next year.
Hydrographic and
Meteorologic Observations North of Iceland
65
LB
conditions observed and reported from the Siglunes transect are not directly correlated to the increased fluxes.
waters north of Iceland.
0
BI
c
The hydrographic variability in the Iceland Sea results essentially from differences in the influences of relatively warm and nutrient rich Atlantic Water on one hand and cold Polar Water on the other hand. Hydrographic
Siglunes section mean temperature and salinity deviations from the 1961-1980 mean, as indicators of hydrographic indicators in the
1
IP
the increased total particle fluxes were sustained from May through September with a maximum peak in July of 526 mg m day resulting in a yearly total particle flux of 42.7 g m yr .
Year
Year
-1
GB
4
of 39.7 percent CaCO3 and 21.7 percent biogenic SiO2. In contrast to these typical annual particle fluxes in this area, we have observed greatly increased total particle fluxes during the 1998-1999 collecting period. In 1998
1960
GB
-1
N, 12.6˚ W) and collected monthly particle flux samples from 1987 to present. Prior to 1998, seasonal maximum peak particle fluxes were sporadic, of short duration and variable, fluctuating from 14.5 mg m day (Nov.
-0.4
1950
0
The Marine Research Institute (MRI), Reykjavik, Iceland, and the Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA, USA, have deployed a time series sediment trap at 1457 meters in the Iceland Sea (68.0˚
-0.2
EQ
1950
Temperature deviation ∞C
Si-Bio
60
1
-3
Salinity deviation
0°
Sea and the Polar (blue) and Atlantic (green)
Greenland Basin, South Greenland Basin) and the deep ocean particle fluxes collected in
the area of the Nordic Sea influenced by Atlantic extension waters in green (Bear Island,
-2
Salinity deviation
10°
Positions of the Sediment Traps in the Nordic
lected in the area of the Nordic Sea influenced by polar water in blue (Fram Strait, North
1997
200.00
2
-0.4
-6
60°
0
FS
Jan
0.3
LB
GB-1
10
0.3
Temperature deviation ∞C
B1
GB-2
20
0
300.00
30°E
a
50
97
land Sea at 1465m from the years
500.00
80°N
Greenland
600.00
0.4
3
20°
Norway
Greenland
Sea
LANDIC CURRENT
ICE
E.
LAB
RAD
E.
10°
FS
C-org Flux
C-org. Flux g/m2/yr
NT
GR
OR
EE
NL
AN
DC
N
UR
RE
70˚
GREENLAND
0°
Svalbard
98
Iceland Sea Particle Flux: Monthly
mole % normalized
˚N
80
The Iceland sea is an area where temperate and arctic fronts influence both atmospheric and oceanographic conditions. The Irminger Current is a branch of
the North Atlantic Current that carries
relatively warm Atlantic water northward
and west of Iceland where it splits at the
Greenland-Iceland Ridge. One branch of
the Irminger Current swings west and
south to form the cyclonic circulation of
the Irminger Sea and the other branch,
generally smaller, rounds the northwest
peninsula of Iceland and flows eastward
on the shelf as the North Iceland
Irminger Current. The Interannual hydrographic variability is much greater north
of Iceland in the Iceland Sea than south
of the Island, and it results mainly from
the input of different proportions of Atlantic Water and Polar or Arctic Water
into this area.
30°W
4
Total Flux
Total <1mm Flux g/m2/yr
30˚
E
30˚
W
E
Nordic Sea Particle Flux
60
700.00
Total Flux mg/m2/day
60˚
˚W
60
Iceland Sea Particle Flux
Area of Research:
Location of Iceland Sea Sediment Trap Mooring, 1986 – present