SULFUR HEXAFLUORIDE AT CAPE GRIM: LONG TERM TRENDS AND REGIONAL EMISSIONS

Sulfur hexafluoride (SF6) has been measured at Cape Grim since 1978 via a combination of in situ and flask measurements, including measurements on the Cape Grim air archive. The long-term growth rate of SF6 as observed at Cape Grim has increased from 0.1 ppt yr -1 in the late 1970s to 0.24 ppt yr -1 in the mid-1990s. Since then the growth rate has remained relatively constant at 0.23±0.02 ppt yr -1 , indicating relatively constant global emissions (±10 %) since 1995. Pollution episodes at Cape Grim have been used to estimate regional (Melbourne and environs) and Australian emissions of SF6 at 3±1.5 and 15±7.5 tonnes yr -1 during 2001-2003.