Meteorological Controls on Giant Tabular Iceberg Calving From the Antarctic Ice Sheet: A case study of C19 and the “herbie” of May 2002

One of the unsolved mysteries in study of Earth's climate system is the identification of the environmental triggers that lead to the calving of large tabular icebergs from Antarctic tidewater glacial systems. Prevailing thought holds that calving events are not related to meteorological conditions (i.e., only slow glaciological evolution of the ice flow determines when and how large icebergs break off the seaward margins of the ice sheet). Here we present evidence that suggests the contrary: that calving of large 100's to 1000's of km² sized tabular icebergs can be triggered by severe events in Antarctic weather. In our case study of the calving of the 1000 km² iceberg C19 in May 2002, we document a severe “herbie” (hurricane/blizzard) that coincided with the break-off of the iceberg from the Ross Ice Shelf. We combine automatic weather station observations of the weather regime (using stations located on both the Ross Ice Shelf and a nearby iceberg B15A) with satellite imagery of iceberg position and sea ice conditions and seismological observations of iceberg tremor to pin down a timeline of calving. The results, and fundamental modeling considerations, suggest that meteorological conditions can have an important influence on iceberg calving and thus on the mass balance of the Antarctic ice sheet.