Abstract. Productivity in the Southern Ocean (SO) is iron-limited, and supply of iron dissolved from aeolian dust is believed to be the main source from outside the marine environment. However, recent studies show that icebergs could provide comparable amount of bioavailable iron to the SO as aeolian dust. In addition, small scale areal studies suggest increased concentrations of chlorophyll, krill, and seabirds surrounding icebergs. Based on previous research, this study aims to examine whether iceberg occurrence has a significant impact on marine productivity for the entire SO (south of 40° S), using remote sensing data of monthly iceberg amount and monthly ocean net primary productivity (NPP) covering the period 2002–2014. Using global and geographically weighted multiple linear regression models, and controlling for temperature, our analyses show that iceberg presence has a small, yet statistically significant, positive impact on the SO NPP. NPP in the SO is largely influenced by temperature, which could explain 43 % of the total variance in NPP with the standardized coefficient of 0.68. However, in places with iceberg presence, temperature influence weakens, indicated by lower partial temperature R2 (0.19) and standardized coefficient (0.45). Meanwhile, iceberg probability could independently explain 2 % of the NPP variance with a standardized coefficient of 0.15. Although small, this influence is statistically significant at 0.01 level. The geographically weighted regression model reveals spatial variation of these relationships. The results suggest that as iceberg quantity increases, their positive influence on NPP also increases, as indicated by increasing iceberg partial R2 and standardized coefficient in the models.
Wu, S.-Y. and Hou, S.: Impact of Icebergs on Net Primary Productivity in the Southern
Ocean, The Cryosphere Discuss., doi:10.5194/tc-2016-166, in review, 2016.