A bio-optical aproach to understanding long term changes in the Southern Ocean biological carbon pump

Abstract

Climate models and decadal data sets predict changes in the earth's climate that will influence the effectiveness of the Southern Ocean CO2 sink. The sensitivity of the biological carbon pump to climate change is however unknown. Part of the reason for this lies in our inability to accurately resolve the response of the biology to variability in physical drivers at inter-annual, seasonal and intra-seasonal time scales. This is partially due to operational limitations that have influenced the drive for autonomous and remotely sensed techniques that are able to address the temporal and spatial scale gaps in a hitherto under sampled ocean. It is thus important to maximise the value of these observations by developing ecosystem-appropriate, well characterised product s. This SANAP funded research aims to derive optimized and regionally robust information from ocean colour and autonomous platforms in the Southern Ocean to provide new insight into ecosystem function. This is achieved through gathering large amounts of bio-optical, biogeochemical and physiological data to parameterise the particle field {which is dominated by the phytoplankton community) through empirical relationships between Inherent Optical Properties, size, pigment and carbon content. These relationships can then be applied to autonomous data sets to derive important biogeochemical parameters from in situ optical sensors. Furthermore, in conjunction with radiative transfer models and reflectance inversion algorithms these relationships can be applied to satellite derived ocean colour data to investigate biological responses {in community structure, production and export potential) to physical forcing mechanisms at the time and space scales required for answering climate response questions.