Climatic Influences on Southern Hemisphere Oceanic Primary Production Derived From Satellite Remote Sensing Observations

• Main Authors: Couto, AB, Maharaj, AM, Holbrook, NJ
• Format: Conference Object
• Language: English
• Published: American Meteorological Society & AMOS 2009
• Subjects: Earth Sciences; Oceanography; Physical Oceanography; Indian; Pacific; Southern Ocean
• Online Access: http://ecite.utas.edu.au/61418

Oceanic phytoplankton growth is essential tothe sustainability of ocean biota (Field et al. 1998).Oceans primary productivity varies in response toenvironmental conditions, such as sunlight and nutrientavailability. These factors restrain the reproduction andgrowth of drifting algae. In the southern hemisphereseveral climate signals exist which may modulate oceanprimary productivity such as the El Nio SouthernOscillation (ENSO), the Indian Ocean Dipole (IOD) inthe tropical Indo-Pacific region (Saji et al. 1999; Wolter;Timlin 1998) and the Southern Annular Mode (SAM) inthe polar and sub-polar regions (Mo 2000a). Oceanprimary productivity is thought to response indirectly tothese climate modes of variability, by the circulationchanges that these induce (Behrenfeld et al. 2006).Changing circulation patterns may origin an anomalousupwelling (or downwelling), leaving anomalous nutrientsignatures in the euphotic layer, where primaryproductivity will anomaly correspond (Lovenduski;Gruber 2005). Additionally, the southern hemispherealso includes the unique region of the Southern Ocean,which is a critical component of the global circulationand the biogeochemical cycles of nutrients and carbon(Arrigo et al. 2008). Phytoplankton growth patternsadapt to different regions depending on the intrinsicconditions of each region.As vast and rapidly changing as the ocean is,satellite imagery provides an ideal tool to observe andillustrate, at a high sampling rate, several oceaniccharacteristics, including its colour (McClain et al. 2004).Using the appropriate algorithm, one is able to retrievenot only chlorophyll concentrations, from satelliteobservations but also phytoplankton estimates (Morel;Berthon 1989).In this study we use Empirical OrthogonalFunctions (EOF) to evaluate satellite derived chlorophyllconcentrations. The use of EOF is an ideal tool toobserve cyclical patterns within continuous observations(Bjornsson; Venegas 1997).This paper explores the relationship betweenlarge-scale climate modes of variability (ENSO, IOD andSAM) and phytoplankton distribution patterns across thesouthern hemisphere oceans.