Atmospheric sampling of Supertyphoon Mireille with NASA ...

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NEWELL ET AL: DC-8 SAMPLING OF TYPHOON MIREILLE 1859
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Intensive sampling was carried out in three regions: the also contains the flight altitude, and Figure 4e includes
boundary layer inflow region at about 300 m between ambient air temperature. Time resolution of the data used
0241 UT and 0315 UT; the eye and surrounding wall cloud in Figure 4a is given with the Figure 4a caption. For other
region, sampling at about 11.3 and 12 km between 0457 constituents the data are collected at variable intervals and
and 0535 UT; and the outflow region (a term used here to are plotted at the midpoint of the collection interval. Each
denote the northeast quadrant) between 0550 and 0714 UT. time series set has the boundary layer and eye regions
The aircraft-reported winds are plotted in Figure 3a-3c for marked on the time axis. Constituents having their lowest
these three regions. Where available, radiosonde winds values in the boundary layer included CO, 03, SO2, C2H2,
(see, for example, Figure 3c) and winds from commercial C2H6, C3H8, C6H6, NO, NOy, and PAN. PAN is actually
aircraft flights (AIREPs) are also included (see, for below the detection limit; its concentration is very sensitive
example, Figure 2). Most of the body of this paper deals to temperature, decreasing at higher temperatures [Singh,
with the atmospheric chemistry findings in these three 1987]. Thus indications are that the air entering the
regions and their possible interpretation in terms of typhoon from the south in the southeastern sector is clean
atmospheric motions.
marine air. The marine origin of the inflow was also
indicated by the fact that the highest DMS values of the
mission occurred in the boundary layer. The higher
aerosol concentrations in the boundary layer (Figure 40 are
2. Results of Boundary Layer Sampling thought to be associated with sea salt.
In addition to the time series of constituents themselves,
time series of ratios of two pairs of constituents which can
Time series of selected constituents are examined first be interpreted in terms of air mass age are presented in
to place the boundary layer inflow region in proper Figure 4g. As discussed elsewhere [Gregory et al., this
perspective. Figure 4 includes time series for the entire issue], an acetylene/CO ratio of 1 suggests emissions only a few
(DMS), 802, C2H2, C2H6, C3H8, C6H6, NO, NOy, .days old. These values apply when acetylene is expressed
CH3C(O)OONO 2 (peroxyacetyl nitrate (PAN)), H202, in pptv and CO is in ppbv. The lifetime of acetylene
CH3OOH, OH (model calculated), and aerosol. Figure 4a (C2H2) is about 11 days, while that of carbon monoxide is