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The lunar and solar semidiurnal variations of barometric pressure at Copenhagen, 1884–1949 (66 years)
Author(s) -
Chapman S.
Publication year - 1969
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49709540410
Subject(s) - atmospheric sciences , amplitude , mean value , range (aeronautics) , seasonality , atmospheric tide , environmental science , atmospheric pressure , climatology , meteorology , physics , geology , mathematics , thermosphere , ionosphere , statistics , materials science , quantum mechanics , astronomy , composite material
Sixty‐six years of bihourly barometric data for Copenhagen (55°·7N) are used to determine the lunar atmospheric tide there, L 2 ( p ), and also the harmonic components S n of the solar daily barometric variation S ( p ), for n = 1, 2, 3, 4, For L 2 ( p ) seasonal means are given as well as the annual mean; for S 2 ( p ) monthly, seasonal and annual mean values are given. The determinations are made for groups of days with different upper limits of range, 6·0 microbars (μb) and 8·7 ph, as well as for all days. It is shown that it is advantageous to exclude the days of larger range from the determination of L 2 ( p ). Days of larger range are most frequent in winter. At that season, for days of smaller range, the mean pressure is higher than in summer. The 66‐year mean annual value of L 2 ( p ) is 10·3 sin (2 r + 87°·3) μb, with probable error 2·5 μb; for S 2 ( p ) it is 225 sin (2 t + 130°·8), with probable error 2·8 μb; here r and t denote respectively lunar and solar mean local time. Thus, in amplitude, S 2 is 21·9 times L 2 , and in phase S 2 exceeds L 2 by 43°·5; L 2 and S 2 at Copenhagen vary seasonally in different ways; in both cases these variations are similar to those observed elsewhere in northern Europe. The corresponding amplitudes for Oslo (59°·9N), found by Haurwitz and Cowley (1967), are somewhat smaller, as might be expected.