Geoscience Reference
In-Depth Information
Nino event occurred, T
av
and DO were lower, and that the S
av
, nutrients (PO
4
-P
av
, SiO
3
-
Si
av
, and DIN), SS Chl-a were higher (Table 5, Figure 10). During a La Nina event,
contrary, T
av
and DO were higher, and that the S
av
, nutrients (PO
4
-P
av
, SiO
3
-Si
av
, and
DIN), SS Chl-a were lower (Table 5, Figure 10). The fl uctuations of environmental
parameters evident corresponded to El Nino/La Nina events. Furthermore, in com-
parison of the average values of the environmental parameters in summer of El Nino
years with those of La Nina years, T
av
and DO
av
were lower by 1.89°C and 20.2 μmol
l
−1
, respectively; while S
av
was higher by 0.31 psu; PO
4
-P
av
, SiO
3
-Si
av
, and DIN
av
were
higher by 0.15, 6.41, and 3.42 μmol l
−1
, respectively. Surface Chl-a concentration was
higher by 0.14 mg m
−3
, that is higher by 1.8 times (Table 5), even higher by 0.83 times
than the average value of normal years (1980, 1990, 2000, 2001, and 2003, for which
mean Chl-a = 0.12 ± 0.05 mg m−3).
Table 4.
Annual mean of SST and T
av
along transect N in the nSCS in El Nino and La Nina years
during 1976-2004 (unit: C).
El Nino Year
1976
1982 (1983)
1986 (1987)
1991
1993
1994
1997
2002
2004
Mean±SD
a
SST
23.87
25.82 (25.09)
25.60 (25 .73)
25.08
25.89
26.24
25.77
26.66
26.25
25.64±0.75
T
a
υ
21.13
21.40 (23.40)
23.09 (23.32)
21.46
21.65
21.79
22.25
22.98
22.62
22.27±0.83
La Nina Year
1981
1988
1995
1998
1999
SST
25.09
25.68
25.74
26.61
26.21
25.87±0.58
T
a
υ
23.28
23.72
24.00
24.07
24.51
23.92±0.46
Table 5.
The mean of the ecological parameter for the water column (0-200 m) and sea surface Chl-a
concentration at Station 4 in summer of El Nino/La Nina years during the study period (units: °C for
temperature, psu for salinity, μmol l
−
1
for DO and nutrients and mg m
−
3
for Chl-a).
El Nino Year
1976
1982 (1983)
1986 (1987)
1991
1993
1994
1997
2002
2004
Mean±SD
a
T
a
υ
21.13
21.40 (23.40)
23.09 (23.32)
21.46
21.65
21.79
22.25
22.98
22.62
22.26±0.80
S
a
υ
34.18
34.14 (34.16)
34.13 (34.2)
34.45
34.82
34.41
34.19
33.85
34.17
34.25±0.25
DO
a
υ
365.6
380.1 (387.3)
355.1 (364.9)
379.2
337.3
368.5
339.0
354.2
357.8
362.6±16.0
P0
4
-P
a
υ
0.23
0.71
0.36
0.56
0.44
0.56
0.48±0.17
Si0
3
-Si
a
υ
25.36
16.22
13.38
8.96
11 .65
10.56
14.36±5.94
DIN
a
υ
3.20
3.85
6.19
4.29
12.51
8.12
6.36±3.50
Chl-a
b
0.31
0.17
0.18
0.22±0.08
La Nina year
1981
1984
1988
1995
1998
1999
T
a
υ
23.28
25.30
23.72
24.00
24.07
24.51
24.15±0.70
S
a
υ
33.89
34.06
34.01
33.60
34.18
33.90
33.94±0.20
DO
a
υ
391.7
431 .0
388.2
380.8
308.7
396.2
382.8±40.3
P0
4
-P
a
υ
0.20
0.23
0.56
0.33±0.20
Si0
3
-Si
a
υ
10.00
5.20
22.32
7.95±12.45
DIN
a
υ
3.50
3.00
2.31
2.94±5.98
Chl-a
b
0.08,0.06
0.08
0.09
0.08±0.01
a
Mean±SD is the multi-year mean value ± standard deviation for the El Nino/La Nina years.
b
The Chi-a data were derived from SeaWiFS during 1998-2004, from Nimbus-7 CZCS in 1980 and 1984, provided by X.
Chen, from The Third Institute of Oceanography, SOA, China for 1982, Fan (1985) and Huang (1992) for 1990, respectively.
