We report on the physical properties of solar sequential chromospheric
brightenings (SCBs) observed in conjunction with moderate-sized chromospheric
flares with associated CMEs. To characterize these ephemeral events, we
developed automated procedures to identify and track subsections (kernels) of
solar flares and associated SCBs using high resolution H-alpha images.
Following the algorithmic identification and a statistical analysis, we compare
and find the following: SCBs are distinctly different from flare kernels in
their temporal characteristics of intensity, Doppler structure, duration, and
location properties. We demonstrate that flare ribbons are themselves made up
of subsections exhibiting differing characteristics. Flare kernels are measured
to have a mean propagation speed of 0.2 km/s and a maximum speed of 2.3 km/s
over a mean distance of 5 x 10^3 km. Within the studied population of SCBs,
different classes of characteristics are observed with coincident negative,
positive, or both negative and positive Doppler shifts of a few km/s. The
appearance of SCBs precede peak flare intensity by ~12 minutes and decay ~1
hour later. They are also found to propagate laterally away from flare center
in clusters at 41 km/s or 89 km/s. Given SCBs distinctive nature compared to
flares, we suggest a different physical mechanism relating to their origin than
the associated flare. We present a heuristic model of the origin of SCBs.Comment: 24 pages, 17 figure
