  Protoplanetary disc systems observed at radio wavelengths often show excess
emission above that expected from a simple extrapolation of thermal dust
emission observed at short millimetre wavelengths. Monitoring the emission at
radio wavelengths can be used to help disentangle the physical mechanisms
responsible for this excess, including free-free emission from a wind or jet,
and chromospheric emission associated with stellar activity. We present new
results from a radio monitoring survey conducted with Australia Telescope
Compact Array over the course of several years with observation intervals
spanning days, months and years, where the flux variability of 11 T Tauri stars
in the Chamaeleon and Lupus star forming regions was measured at 7 and 15 mm
and 3 and 6 cm. Results show that for most sources are variable to some degree
at 7 mm, indicating the presence of emission mechanisms other than thermal dust
in some sources. Additionally, evidence of grain growth to cm-sized pebbles was
found for some sources that also have signs of variable flux at 7 mm. We
conclude that multiple processes contributing to the emission are common in T
Tauri stars at 7 mm and beyond, and that a detection at a single epoch at radio
wavelengths should not be used to determine all processes contributing to the
emission.
