Phytoplankton Bloom Dynamics in the Southern Ocean Marginal Ice Zone

Analysis of satellite ocean color and wind speeds within the seasonal ice zone (SIZ) of the Southern Ocean sheds new light on the physical processes that influence phytoplankton biomass distributions. A compilation of monthly averaged chlorophyll and percent sea ice cover data within the SIZ from 1997-2005 has been compared to monthly average wind speed data from 1999-2005. Along with the analysis of chlorophyll and wind speed data, some significant statistics on the temporal and spatial dynamics of the marginal ice zone (MIZ, areas of recent ice melt) have been recorded including monthly MIZ areal extent, phytoplankton bloom area within the MIZ, and variances of these. MIZ areal extent was fairly consistent from year to year, always peaking in December, with a mean area of 6,033,253 km2 and a mean area within the MIZ with phytoplankton blooms (chlorophyll exceeding 0.8 mg/m3) of 350,509 km2. While the bloom areal extent seems very small compared to the MIZ, in reality, because of gaps in the chlorophyll data, bloom regions comprise a much larger percentage of the MIZ. The bloom area percentage ranges from 2% in September and October to 23% in February. December always has the largest sea ice retreat, but MIZ mean chlorophyll concentrations usually do not peak until February. Scatter plots of wind speed vs. chlorophyll concentrations suggest a wind threshold of around 10 m/sec, above which it is less likely to see phytoplankton blooms within the MIZ. This threshold doesn't seem to hold for all months, primarily only November - January.