In addition, during days near the peak of the burning
period, the PAR/K↓ ratio tended to be lower in
the morning period and higher in the afternoon for
a given zenith angle. This can be accounted for by
an increase in the dispersion of aerosols associated
with an increase in the ventilation factor throughout
the day. During the morning hours, when windspeeds
are low, resulting in a stable atmosphere and a shallow
mixed layer, aerosol dispersion is inhibited, increasing
the turbidity. Thus, the effect of pyrogenic
aerosols on the PAR/K↓ ratio would also tend to be
greater. During the afternoon, intense surface heating
increases surface turbulence and convective activity
in the boundary layer. This results in an increase in
the ventilation factor as both windspeed and the depth
of the mixed layer become greater. The dispersion
of aerosols becomes greater and leads to an overall
decrease in turbidity. Such linkages to and implications
of regional airflow remain a topic for further
study.