144
CITY OF CHICAGO POLLUTION INCIDENTS: CASE STUDIES*
DF. Gatz and £. W. Kiappenbacht
Chicago weather phenomena and SO: pollution sources interact In a number of different ways to produce episodes of
through the eity may have caused the unusually high pollution of that dav. The two remaining cases involved winds off
sented in this paper were a first step in our study of the
than the lake surface. The other involved a shift to east
severe pollution. The three high-pollution case studies pre-
Lake Michigan. One was a lake breeze, with the land warmer
weather associated with Chieago pollution. This information
4,
%
winds aver the whole region In response to a pressure gradient
ao
a
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ass<O.
a,
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o,
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4
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Bp
“02,
On
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112
sor?
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Fie. 105.—19 January 1966 surface weather map, 1200 CST
is crucial to our efforts to build an SO: prediction model for
the city.
The first case examined was evidently a heat-island circulation. Winds converged over the axis of the city heat island
reorientation. In this case, the lake surface was warmer than
the land. In both cases. observed poliution conditions were
generally consistent with theoretical expectations.
from northwest and northeast on 2 clear, cold, nearly calm
INTRODUCTION
winter afternoon. There is evidence that recirculation of air
* This paper was prepared for presentation at the Air Pollution Control Association Annual Meeting, New York, June
24, 1969.
7 Senior Meteorologist, City of Chicago Department of Air
Pollution Controi.
Argonne National Laboratory scientists are developing an SOx pollution prediction model for Chicago.
To be useful, the model must be able to predict high
concentrations accurately. For the model to predict
high concentrations accurately we must provide it