| Polar regions have been disproportionately affected by recent changes in climate, including the dramatic reduction in sea ice thickness and extent, increased air temperature, and an increase in river discharge. In light of these recent environmental changes, three key aspects of the carbon biogeochemistry in both polar oceans have been assessed as part of this dissertation.;Second, changes in sea ice and primary production in the Arctic Ocean were quantified for the period 1998-2006. For this purpose, multi-platform satellite data were used to derive best estimates of open water (ice free water) area, sea surface temperature (SST) and Chl in conjunction with a primary production algorithm. Interannual variability in primary production over the entire Arctic Ocean, as well as in the various geographical and ecological sectors, was assessed. Results show that, since 1998, open water area in the Arctic has increased at a rate of 0.07 x 106 km2 yr-1, with the greatest increases in the Barents, Kara, and Siberian sectors, particularly over the continental shelf. Between 1998 and 2006, mean annual open water area in the Arctic Ocean increased by 19%. The pan-Arctic primary production averaged 419+/-33 Tg C yr-1 during 1998-2006 reaching a nine-year peak in 2006.;Finally, air-sea flux of CO2 (FCO2) was quantified in the Arctic Ocean for the period 1998-2003. For this purpose, dissolved inorganic carbon and total alkalinity were estimated from in-situ measurements of salinity, sea surface temperature (SST), and Chl. This allowed computation of the partial pressure of CO2 and the quantification of air-sea flux of CO2 using salinity, SST and, wind speed. Pan-Arctic application of this algorithm was accomplished using a combination of remotely sensed chlorophyll and modeled derived SST and salinity. The results show that Arctic Ocean is a net sink of atmospheric CO2, with an annual flux of 169+/-9 Tg C yr-1 from the air to the ocean. This is about 8% of the world's uptake of CO2. Increasing annual FCO2 with time was observed only in Siberian sector which was due to a significant increase in open water area.;Thus, this study contributes towards better understanding of the carbon biogeochemistry in the polar oceans and facilitates future assessment of the same in these regions.;First, a new satellite remote sensing algorithm was developed to measure particulate organic carbon in the surface ocean directly from space. This approach was a departure from the conventional method of converting satellite-baased estimates of chlorophyll (Chl) to carbon (C) using an empirically-derived C to Chl ratio. Application of this algorithm to the Ross Sea, Antarctica helped to quantify concentrations of particulate organic carbon in waters dominated by two dominant bloom-forming phytoplankton taxa that differ markedly in their ability to draw down carbon dioxide (CO2). |
