The areas and ice production of the western and central Ross Sea polynyas, 1992–2002, and their relation to the B-15 and C-19 iceberg events of 2000 and 2002

For 1992–2002, the paper investigates the heat loss and area of three polynyas in the western and central Ross Sea. These are the Ross Sea Polynya (RSP) and the much smaller Terra Nova Bay and McMurdo Sound polynyas. The importance of these polynyas is that their associated salt rejection contributes to the formation of the High Salinity Shelf Water (HSSW) that is crucial to the Antarctic Bottom Water formation. The study divides into two parts, 1992–1999, when there was negligible iceberg activity, and 2000–2002, when major icebergs calved and interacted with the polynyas. To retrieve the ice thicknesses and heat fluxes within the polynyas, the paper uses an algorithm based on the ratio of the vertically and horizontally polarized Special Sensor Microwave/Imager (SSM/I) 25-km resolution 37-GHz channels, combined with meteorological data. Because of sidelobe contamination, the ice shelf and icebergs are masked. Our results show that for the polynyas, and consistent with other observations, their mean winter area is about 30,000 km2 and their combined ice production is about 500 km3y− 1. We also find that the polynya ice production approximately equals the ice export. This is in contrast to the Weddell Sea, where the polynya ice production equals about 6% of the ice export. For the years 2000 and 2002, the calving of large icebergs directly affect the ice production by inhibiting the ice production off the shelf due to piling up of first year ice upwind of the bergs and by generating new polynyas downwind of the bergs. The period 1992–2001 exhibits an upward trend in polynya productivity. The decadal increase in the ice production suggests that the observed HSSW salinity decrease in the western Ross Sea is not due to the polynyas, but is rather due to a change in the properties of the water flowing into the Ross.