The mean daily march of pressure (hourly values) for each month of the
96 year period 1894-1989 in Athens, Greece is studied using Fourier a
nalysis. The annual variation of the harmonic parameters (amplitude, t
ime of maximum, x and y-components) is examined. The globally excited
2nd and 3rd harmonics show in general the same behaviour as in other p
laces of the Earth. Similar features show the corresponding parameters
of the daily solar radiation march. The first harmonic displays some
local characteristics. The long period fluctuations study revealed sta
tistically significant trends in most parameters of the 2nd harmonic,
most strikingly the 0.5 h shift in the time of its maximum during the
20th century. Power spectrum analysis showed the existence of a bienni
al oscillation in B1, the x-component of the first harmonic, but this
oscillation is mainly confined to the second half of the entire period
. A periodicity of about 6 years which could be associated to the Sout
hern Oscillation was also found in B1 while in A1, the y-component, a
periodicity close to the 11-year solar cycle and another one close to
the nutation of the Earth's axis are present. The lunar tides are too
small to be detected by the same methods. However the semilunar tide w
as revealed to be 10-20 times smaller than the semisolar.