The correlation implies that the same synopticscale
transport mechanisms govern pollution episodes in
both regions. Daily mean maximum mixing depths, which
average 1.1 km (northeast) and 1.3 km (midwest) in the
present-day, increase significantly in the future by 100 –
240 m (p < 0.05), consistent with higher surface temperatures
and greater vertical mixing [Rind et al., 2001]. The
change in future mixing depths is of the wrong sign to
explain the increase in severity of future pollution events