QUESTION:
Is "a decrease in the measured sol average surface pressure" on Mars the
same as a low barometic reading on Earth that is assoicated with a low
pressure?

ANSWER from Bob Haberle on October 9, 1997:
Not necessarily. Because CO2, the major atmospheric constituent, condenses
in the winter polar regions, there is a seasonal fluctuation in surface
pressure that is not associated with low and high pressure systems. To first
order, this fluctuation is generally less than 2 mbars per 300 sols, or
about 0.007 mb per sol. Thus, changes in the daily averaged pressure that
are greater than this would be due to "weather systems". It is quite common
to see such changes during the fall, winter, spring seasons. Summer, on the
other hand, is less variable.