ATMOSPHERIC TRANSPORT PROCESSES
459
35
360
300},
Louees Soon
60
500495
600 +
700 4
BOO 4 cs cesvcccece ce 7
900 =
280
aw
ALB
NYC
DCA
GSO
CHS
JAX
TPA
MIA
Fig. 8—Cross section through the atmosphere from Albany (ALB),
N. Y¥., to Miami (MIA), Fla., at 00 GCT on Nov. 23, 1962, Thin lines
indicate potential temperatures (°K, slanting numbers). Dotted lines
indicate isotachs (mps, vertical numbers). Heavy lines outline stable
regions. Heavy vertical lines over station location mark the extent of
“‘motorboating’’ humidity reports.
cesses that carry stratospheric or tropopause air down to the ground
in one sweeping motion. According to Fig. 9 the average rate of sinking
of this air is approximately 200 mb within 12 hr, or 5.1 cm/sec. This
estimate does not include the air in the northern jet-stream branch of
Figs. 3a and 3b, which may have comeout of the stratosphere but which
travels in the middle troposphere. If this air were included in considerations of stratospheric— tropospheric mass exchange, an estimate of
approximately 1.5 x 10" metric tons of air involved in the transport
process would be more appropriate.
The total amount of air above the 200-mb level (assumed to be the
mean tropopause level) is approximately 1.04 x 107! g, or 5.2 x 10? g in
one hemisphere. The amount of 1.5 x 10% g transported down through
the tropopause by one jet maximum, therefore, constitutes approximately 0.35% of the stratospheric air of one hemisphere, or approxi-
mately 1% of the stratospheric air north of 45° latitude.
So far, we have considered only the effects of one jet maximum.
Assumethat five planetary waves, each carrying a polar front jet maximum, are active around the hemisphere at the same time and that the
subtropical jet stream and the arctic front jet stream have similar