Portal de Periódicos da CAPES

Subtropical fronts observed during the 1996 Central Australian Fronts Experiment

2000; Volume: 49; Issue: 3 Linguagem: Inglês

0004-9743

Michael J. Reeder, Roger K. Smith, Roger Deslandes, Nigel Tapper, Graham Mills,

Tropical and Extratropical Cyclones Research

The 1996 Central Australian Fronts Experiment (CAFE96) was the third in a series of field experiments designed to better understand the structure and dynamics of late dry-season subtropical cold fronts that affect central Australia. In this paper, the behaviour of three fronts observed during CAFE96 are described in detail and the four other fronts that occurred are examined in the light of previous studies. In total, fourteen fronts were documented during the three field experiments, of which twelve crossed central Australia during the evening or early hours of the morning. Only one of the fourteen crossed central Australia during the late afternoon (Event 4 in CAFE96), and only one in the mid-morning (Event 6 in CAFE96). The latter front arrived at Alice Springs during the mid-morning and, as the daytime turbulent mixing increased, it ceased advancing northeastward and retrogressed. It subsequently retreated through Alice Springs, giving way to strong northwesterly winds and blowing dust. The front reversed direction once again and was observed at a station 70 km southeast of Alice Springs during the mid-afternoon. While it is probably quite common for the position of subtropical cold fronts to oscillate back and forth as the daytime turbulent mixing waxes and wanes, Event 6 is the first example to be documented in detail. Event 3 is more typical of the fronts observed in the two previous experiments, but is discussed briefly here because it is the best example to date exhibiting near-surface warming in a strip following the passage of the cold front. This warming was detected in satellite imagery and confirmed by surface measurements.