SIBER SPIS sept 2011.pdf - IMBER

SIBER
Science Plan and Implementation Strategy
The site off SW Indonesia (5°S 95°E) would be the flux site most strongly impacted by the
IOD, with the eastern tropical IO undergoing significant biogeochemical alteration during these
events. A recent analysis of satellite-observed interannual chlorophyll variability, combined
with ocean color based estimates of net primary production (NPP), reveals that the eastern IO
from the equator down to ~ 8°S realizes significant enhancement of phytoplankton biomass
(Wiggert et al., 2009). The NPP estimates show that local production rates can attain up to a
100% increase, with an overall regional increase of >40% recorded during the 1997/98 IOD.
The time series of climatological chlorophyll is plotted for each of the eight Flux Reference Sites
in Fig. A4.2 (note that the y scale on the two plots is different). The upper panel shows the four
western sites and the lower panel is the four eastern sites. The western sites are of general
interest due to their high biological variability. By contrast, the eastern sites have much lower
variability but are interesting for the reasons discussed above. In addition, while productivity
appears low and invariant at the eastern sites in the monthly climatological maps, model
results (Jerry Wiggert, personal communication) suggest that these sites should experience
short-term pulses of physical and biological variability that are not revealed by these coarse
resolution (monthly) climatologies. Higher temporal resolution measurements are required to
validate these results.
In addition, one interesting aspect of the 26°S 97°E mooring is that numerous eddies come off
the Leeuwin Current and the mooring might be able to capture the biogeochemical impact of
these. Research is currently being carried out at Oregon State University (USA) focusing on
these features, i.e. satellite analyses of the sea surface temperature and chlorophyll anomalies
associated with these eddies (see animation provided by Pete Gaube and Dudley Chelton at
http://www.imber.info/SIBER_downloads.html).
Given the preceding discussion, it is difficult to prioritize the RAMA Flux Reference Sites for
chl (mg m-3)
1
0.8
0.6
0.4
0.2
0
0,2
16°S 55°E
EQ 55°E
15°N 65°E
8°S 67°E
J F M A M J J A S O N D
chl (mg m-3)
0,1
0
EQ 80°E
15N 90°E
5°S 95°E
26°S 97°E
Fi g u r e A4.2 Time series of climatological chlorophyll plotted for each of the eight Flux Reference
Sites. Note that the y scale on the two plots is different. The upper panel shows the four western sites
and the lower panel the four eastern sites.
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