Application of Fast Fourier Transform to Ozone Data at Lagos, Nigeria
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Fast Fourier Transform (FFT) is a mathematical too l often used to represent tim e-varying real data set function /(1). In this paper, the FFT was applied to the measured stratospheric ozone data at Lagos from 1997 to 2002. The total number of data set used was 211 giving 2048. Both first order and second order derivatives of the data set were generated using FFT. The total ozone data over
Lagos was latter generated using the derivatives. The simulated ozone data was compared with the
observed ones. The mean ozone concentration value from the observed data was 270.8±0.3D U, its standard deviation was 15.3DU and its range 93.1 D U. For FFT (N - 2048) generated data, its mean was 27 1. 2±0.3DU, its standard deviation was 15.5DU and its range was 79.8D U. The re sult of the
generated data us ing FFT of (N - 2048), and that of the observed values had a correlation of 0.99
while that of (N- 1024) had a correlation value of 0.94. The rate of depletion of ozone in January
and February was also observed to have average values of -0.14DU per day with an average initial
valw: of about 250DU. Similarly the rate of increase in ozone in .July to September was about 0. 3DU
per day with an average initial value of about 28 0D U.
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QC Physics