Heat and moisture budget and trajectory analysis of a warming event observed in June 1997 at Dome Fuji Station, Antarctica

An abrupt warming event occurred during June 17 to June 19 at Dome Fuji Station (3810m a.s.l.) in East Antarctica, in 1997. The surface air temperature increased from -70℃ to -30℃ in two days. The warming event was associated with the intrusion of an anticyclone onto the East Antarctic plateau. European Centre for Medium-Range Weather Forecasts (ECMWF) objective analysis data and Dome Fuji Station sonde data are used to investigate this event. Comparison between the sonde data and the ECMWF data shows reasonable agreement. The temperature increase exceeded 15K at 400hPa within 1.5 days, while the temperature at 150hPa decreased 15K. The heat and moisture budget analyses reveal that this tropospheric warming was caused by strong poleward advection of high potential temperature from lower latitudes, which overcame the cooling effect of the upward motion. On the other hand, stratospheric cooling was caused by the upward motion. Five-day backward trajectory calculations from Dome Fuji Station are performed for June, 1997. Although almost all of the air parcels originated from inside of the polar vortex for the period before the warming, many parcels originated from midlatitudes during and after the warming. This suggests that mixing of air between the polar and mid-latitude regions was enhanced during and after the warming event