Pacific Trade Winds Biome
373
0
20
40
60
80
100
0
5
10
15
Climatology (years)
Depth (m)
Production at DCM (%)
Zm (sigma)
Zeu
Pt (at DCM)
0.25
0.30
0.35
0.40
0.45
0.50
0.00
0.10
0.20
0.30
0.40
0.50
SeaWiFS (PEQD): September 1997 - January 2002
Surface Chl (mg m -3
)
Pt d
-1
Chl m
-3
Pt (gC m
-2
d
-1
)
1998
1999
2000
2001
Fig. 11.12 PEQD: seasonal cycles of monthly surface chlorophyll and depth-integrated autotrophic production
for the years 1997–2002 from SeaWiFS data together with characteristic seasonal cycles of mixed-layer depths
from Levitus climatological data and photic depths computed from characteristic irradiance and the archive
of chlorophyll profiles discussed in Chapter 1.
Synopsis
Case 4—Small-amplitude response to trade-wind seasonality—Mixed-layer depth has only
a weak geostrophically forced seasonality when meaned over the whole area of the
province with slight shoaling twice annually, in April–May and (weaker) in October–
November. Photic depth is consistently deeper, so the thermocline is illuminated in all
months (Fig. 11.12). Seasonal changes in P rate that follow the changes in Z m are so
small (025–035 mg C m
−2 d
−1 ) as to be insignificant when averaged across the whole
province, and chlorophyll biomass is seasonally almost invariant (012–015 mg m
−3 );
interannual differences are, however, significant and respond to the value of the SOI.
Western Pacific Warm Pool Province (WARM)
Extent of the Province
This province lies under the low-pressure region of the atmospheric Walker circulation—
that is, from the date line to the western boundary current that flows NE-SW along the
shelf edge on the eastern side of the Indo-Pacific archipelago. WARM therefore has a
maximum meridional extent (at about 160
E) from 10
N to about 12
S. The southern
boundary of the province passes along the northern coast of New Guinea and then around
the arc of the Solomon Islands. These limits will be found to correspond approximately
with the regional 29
C isotherm at the surface.
373
0
20
40
60
80
100
0
5
10
15
Climatology (years)
Depth (m)
Production at DCM (%)
Zm (sigma)
Zeu
Pt (at DCM)
0.25
0.30
0.35
0.40
0.45
0.50
0.00
0.10
0.20
0.30
0.40
0.50
SeaWiFS (PEQD): September 1997 - January 2002
Surface Chl (mg m -3
)
Pt d
-1
Chl m
-3
Pt (gC m
-2
d
-1
)
1998
1999
2000
2001
Fig. 11.12 PEQD: seasonal cycles of monthly surface chlorophyll and depth-integrated autotrophic production
for the years 1997–2002 from SeaWiFS data together with characteristic seasonal cycles of mixed-layer depths
from Levitus climatological data and photic depths computed from characteristic irradiance and the archive
of chlorophyll profiles discussed in Chapter 1.
Synopsis
Case 4—Small-amplitude response to trade-wind seasonality—Mixed-layer depth has only
a weak geostrophically forced seasonality when meaned over the whole area of the
province with slight shoaling twice annually, in April–May and (weaker) in October–
November. Photic depth is consistently deeper, so the thermocline is illuminated in all
months (Fig. 11.12). Seasonal changes in P rate that follow the changes in Z m are so
small (025–035 mg C m
−2 d
−1 ) as to be insignificant when averaged across the whole
province, and chlorophyll biomass is seasonally almost invariant (012–015 mg m
−3 );
interannual differences are, however, significant and respond to the value of the SOI.
Western Pacific Warm Pool Province (WARM)
Extent of the Province
This province lies under the low-pressure region of the atmospheric Walker circulation—
that is, from the date line to the western boundary current that flows NE-SW along the
shelf edge on the eastern side of the Indo-Pacific archipelago. WARM therefore has a
maximum meridional extent (at about 160
E) from 10
N to about 12
S. The southern
boundary of the province passes along the northern coast of New Guinea and then around
the arc of the Solomon Islands. These limits will be found to correspond approximately
with the regional 29
C isotherm at the surface.