> Why are 850 and 700 mb trajectories significant for previous aerosol studies?
Many previous aerosol studies have used 850 and 750 mb pressure levels in back
trajectory calculations. Why is this significant? Are surface
back trajectory calculations (at 1000 mb) more accurate, due to
presumably greater spatial resolution of meteorological data?
Traditionally, 850 mb and 700 mb trajectories have been used because they
were manually calculated using data on 850 mb and 700 mb charts. In other
words, wind data were available at those levels. 1000 mb trajectories
would generally not be better, even though there are more surface
observations, because 1000 mb can be below ground, and because boundary
layer transport is usually better represented by mid-layer winds rather
than near-surface winds.
