Basic HTML Version
International Journal of Marine Science 2012, Vol.2, No.1, 1
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http://ijms.sophiapublisher.com
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Figure 4 The mean monthly chlorophyll-a data plotted with the 7
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year mean
Note: X-axis shows time in months of a year beginning from January 1998 to December 2004; Left Y-axis shows chlorophyll-a in log
units, right Y-axis shows chlorophyll-a in normal units, both in mg/m
3
of any of the areas we investigated. There was no
secondary maximum observed during the NEM.
1.4 Spectral analysis of monthly mean chlorophyll-a
As seen from the above analysis, chlorophyll-a
variability is largely centered on the SWM and NEM
seasons with the SWM being dominant in most of the
regions of the Arabian Sea. However, a few locations
have shown the variability occurring on other time
scales as well. This aspect is investigated further by
subjecting the monthly mean chlorophyll-a data to
spectral analysis. The variance-preserving spectra are
shown in Figure 5. The annual, semi-annual and
90-day periods are shown at the top of Figure 5.
The chlorophyll-a showed spectral peaks at annual
Figure 5 The variance-preserving spectra of chlorophyll-a for
the selected locations
and semiannual periods off Somalia. The width of the
annual peak was larger compared to the semiannual
peak, reflecting a longer period of productivity during