Quantifying dissolution rates of Antarctic icebergs in open water

At any one time 130 000 icebergs are afloat in the Southern Ocean; 97% of these are too small to be registered in current satellite-based databases, yet the melting of these small icebergs provides a major input to the Southern Ocean. We use a unique set of visual size observations of 53 000 icebergs in the South Atlantic Ocean, the SCAR International Iceberg Database, to derive average iceberg dissolution rates. Fracture into two parts is the dominant dissolution process for tabular icebergs, with an average half-life of 30 days for icebergs < 4 km length and 60 days for larger icebergs. Complete shatter producing many icebergs < 1 km length is rare. A side attrition rate of 0.23 m d(-1) combined with drift speed of 6 km d(-1), or any proportional change in both numbers fits the observed changes in iceberg distribution. The largest injection into the Southern Ocean of fresh water and any iceberg-transported material takes place in a similar to 2.3 x 10(6); km(2) zone extending east-northeast from the Antarctic Peninsula to the Greenwich meridian. The iceberg contribution to salinities and temperatures, with maximum contribution north of the Weddell Sea, differs in some regions, from those indicated by tracking large icebergs.

Automated summary

At any one time 130,000 icebergs are afloat in the Southern Ocean, with 97% of them too small to be registered in current satellite databases. We derive average iceberg dissolution rates using visual size observations from the SCAR International Iceberg Database, finding that fracture into two parts is the dominant dissolution process. The largest injection of fresh water and iceberg-transported material into the Southern Ocean occurs in a specific zone extending from the Antarctic Peninsula to the Greenwich meridian.