Detailed Spatial Analysis of Trends in Primary Productivity in the Ross Sea, Antarctica (1997-2013)

Recent studies have documented an increase in sea ice extent and the duration of the sea ice season in the Ross Sea, Antarctica. We conducted a satellite-based study to quantify changes in net primary production (NPP) and chlorophyll a (Chl a) in response to the observed changes in ice dynamics in the Ross Sea south of 60°S. Our study covers a 16-year time period (1997-2013) and incorporates both the shelf and off-shelf regions of the Ross Sea. We also looked at remotely sensed sea surface temperature (SST) and open water days (OWDs) from 1992 to 2013. We saw a significant decrease in OWDs and SST with time in the off-shelf region, consistent with reports of previous studies. We also saw significant secular changes in NPP in the off-shelf region, with NPP increasing on the eastern side and decreasing in the western side of our study area. Finally, we examined the influence of the Southern Annular Mode (SAM) and the El Niño Southern Oscillation (ENSO), on SST, OWDs, Chl a, and NPP in the Ross Sea and observed a significant relationship between the state of the SAM and ENSO and SST, OWDs, and NPP area across the study region. However, the response of OWDs, SST, and NPP to atmospheric forcing by SAM and ENSO was opposite for the shelf and off-shelf regions, such that during a positive phase of SAM or negative phase of ENSO SST, OWDs, and NPP increased on the shelf and decreased in the off-shelf region.