Cumulative light exposure

Ben Raymond (AAD/ACE-CRC), Klaus Meiners (ACE-CRC), Charles Fowler (University of Colorado), Benedicte Pasquer (ACE-CRC), Guy Williams (Hokkaido University/ACE-CRC)

The model

We have developed a computational model of the large-scale cumulative light exposure of sea ice in the Southern Ocean off east Antarctica (30°E—150°E). The model uses remotely-sensed or modelled sea ice concentration, snow depth over sea ice, and solar irradiance data, and tracks sea ice motion over the season of interest in order to calculate the cumulative exposure of the ice field to photosynthetically active radiation (PAR). Light is the limiting factor to sea ice algal growth over winter and early spring, and so the results have implications for the estimation of algal biomass in East Antarctica.

Figure 1. Estimated cumulative PAR exposure of sea ice in east Antarctica. (a) Mean, and (b) SD across the 1979—2004 autumn-spring seasons. Units are W.days/m^2.

The model results (Figure 1) indicate that highly light-exposed ice is restricted to within a few degrees of the coast in the eastern part of the study region, but extends much further north in the 30°E—100°E sector. In this sector, there is a northward transport of winter sea ice, which advects ice from coastal areas.

The model estimates of cumulative PAR were found to correlate with satellite estimates of subsequent open-water chlorophyll-a concentration, consistent with the notion that sea ice algae can provide inocula for phytoplankton blooms.

References

• Raymond, B., Meiners, K., Fowler, C., Pasquer, B., Williams, G.D., and Nicol, S. (2008) Cumulative solar irradiance and potential large-scale sea ice algae distribution off east Antarctica (30°E—150°E). Polar Biology DOI 10.1007/s00300-008-0538-5.
• Raymond, B., Meiners, K., Curran, M., and van Ommen, T. (2006) A conceptual model of the large-scale distribution of sea ice algae off East Antarctica. Abstracts of the SCAR Open Science Conference, Hobart, 12-14 July 2006.
• Meiners, K., Raymond, B., Williams, G., Massom, R., Nicol, S. (2005) A conceptual model of the large-scale distribution of sea ice algae off East Antarctica during the autumn-winter transition. Dynamic Planet Conference, Cairns, August 22-26 2005

Related resources

• Metadata record including link to data