From: zaphiri@watson.ibm.com (Zaphiris Christidis)
Subject: Re: ENVIRONMENT: Greeks buying ''cleane
Date: Tue, 21 Jul 1992 15:10:47 GMT
Reply-To: zaphiri@watson.ibm.com  (Zaphiris Christidis)
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
Organization: IBM T.J. Watson Research Center.

In article <92Jul21.014448edt.47915@neat.cs.toronto.edu>, ccc@cs.toronto.edu ("Christina C. Christara") writes:
>
> I wouldn't say more industrialized, but certainly enough to get smogged.
> But Thessaloniki has 2 features different than Athens.
> 1) Open valley/prairies from the north, where river Axios runs,
> and where strong North winds are coming (known as Borias).
> 2) A direct seashore. Athens is not so close to the sea.
> Thessaloniki, having the sea from the south, has a free space
> to let the smog go.

In a nutshell, the Athens pollution problem is a lot more complicated than
it originally appears. I am not sure about the accuracy of numbers like
'tenfold' etc. I suppose they were obtained by some method. However, I
believe, no extensive study was done yet, to assert with a reasonable degree
of certainty the pollution numbers quoted.  The main problem is that we do
not have enough observation stations in the Athens bay area, to report
concentrations of the various pollutants.  These observations, can be used
as initial conditions to weather models, as well as photochemical models.
So if you don't have accurate initial data, everything else is just an
educated guess.

It is well established (studies in the LA area) that this type of pollution
is to a large degree due to automobile emissions. The cars emit most of
their pollutants when they idle or when they accellerate. This is the
characteristic of the stop-and-go traffic experienced in the center of
Athens. The emitted nitric oxides, hyrdocarbons, etc, are dispersed in
the atmosphere, and in the absence of strong winds are very well 'baked' by
the sun, where ozon is produced. The entire by-product of the complex
photochemistry, appears as smog (nefos). Athens is unlucky to have
obstructions from the north, so the smog is really trapped above Athens.
The local weather effect known as sea-breeze, moves the smog towards south
at the end of the day, but brings it back in in the early morning hours
where the emissions are high (people driving to their work). The see-breeze
has the tendency to push the smog towards noth, but due to the mountain
ranges, it remains stagnent. This is a very characteristic scenario during
the summer months.

Thessalokiki, has a similar problem, but much less traffic. Sea-breeze
can move pollutants back and forth, but an occational strong wind will
disperse them towards south (dominant direction).  There is no
trapping of the pollutants towards north, so their local concentrations
are relatively low, and their average lifetime over the city is small,
to give them the opportunity to 'bake', thus forming smog.  However,
many times lately, as I drove from Panorama to Thessaloniki, I noticed
a distict smog layer over the city, though much less in extend and magnitude
of the smog in Athens.


> C. Christara

--
Zaphiris Christidis
zaphiri(@watson.ibm.com @yktvmh.bitnet)