  We study the synchrotron flaring behaviour of the blazar 3C279 based on an
extensive dataset covering 10 years of monitoring at 19 different frequencies
in the radio-to-optical range. The properties of a typical outburst are derived
from the observations by decomposing the 19 lightcurves into a series of
self-similar events. This analysis is achieved by fitting all data
simultaneously to a succession of outbursts defined according to the
shock-in-jet model of Marscher & Gear (1985). We compare the derived properties
of the synchrotron outbursts in 3C279 to those obtained with a similar method
for the quasar 3C273. It is argued that differences in the flaring behaviour of
these two sources are intrinsic to the sources themselves rather than being due
to orientation effects. We also compare the start times and flux densities of
our modelled outbursts with those measured from radio components identified in
Very Long Baseline Interferometry (VLBI) images. We find VLBI counterparts for
most of our model outbursts, although some high-frequency peaking events are
not seen in the radio maps. Finally, we study the link between the appearance
of a new synchrotron component and the EGRET gamma-ray state of the source at
10 different epochs. We find that an early-stage shock component is always
present during high gamma-ray states, while in low gamma-ray states the time
since the onset of the last synchrotron outburst is significantly longer. This
statistically significant correlation supports the idea that gamma-ray flares
are associated with the early stages of shock components propagating in the
jet. We note, however, that the shock wave is already beyond the broad line
region during the gamma-ray flaring.
