Publication Date:
2016-05-30
Description:
The northern Arabian Sea hosts a winter chlorophyll bloom, triggered by convective overturning in response to cold and dry northeasterly monsoon winds. There is currently no consensus about the processes responsible for the interannual variations of the magnitude of this bloom. The current study aims at identifying these processes using both observations (including remotely sensed chlorophyll data and physical parameters derived from Argo data) and a coupled biophysical ocean model simulation. Six different remotely sensed chlorophyll products are compared and they show a good phase agreement at seasonal and interannual timescales, but significant discrepancies in bloom amplitude. Both model and observations indicate that the interannual fluctuations of the winter bloom amplitude are strongly tied to mixed layer depth interannual anomalies (correlation ~ 0.6 to 0.7), which are themselves controlled by the net heat flux at the air-sea interface. Our results suggest that mixed layer depth control of the bloom amplitude ensues from the modulation of nutrient entrainment into the mixed layer. In contrast, our results show insignificant correlations between the bloom amplitude and thermocline depth, which precludes a control of the bloom amplitude by daily dilution down to the thermocline depth, as suggested in a previous study.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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