Geomagnetic lunar analysis by least-squares

Malin, S. R. C.; Schlapp, D. M.

doi:10.1111/j.1365-246x.1980.tb04817.x

Cited by 36 publications

(27 citation statements)

References 8 publications

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“…This is closely similar to that described by Malin and Schlapp (1980). For a given observatory, each nighttime mean provides an equation of condition of the form H (t) = H 0 + a 0 t + a 1 cos t + b 1 sin t + a 2 cos 2t + b 2 sin 2t, where t increases from 0 to 2π from January 0.0 to December 31.0, H 0 represents a constant term, a 0 t the secular variation (assumed to be linear over the 2-year interval analysed), a 1 cos t +b 1 sin t the annual variation and a 2 cos 2t +b 2 sin 2t the semi-annual variation.…”

Section: Methods Of Analysissupporting

confidence: 78%

Semi-annual variation of the geomagnetic field

2014

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Nighttime hourly mean values of D, H and Z (or X , Y and Z in a few cases) from 113 observatories for the interval 1964.0 to 1966.0 have been analyzed to determine the semi-annual variation. Results from the 84 observatories with dip latitudes between ±60• have been subjected to spherical harmonic analysis to determine the coefficients of the internal and external parts. Only those coefficients that are found to be significantly different from zero at the 5 per cent level have been included.One of the main objectives is to obtain a reliable estimate, with confidence limits, of the internal/external ratio at a very low frequency for constraining estimates of the deep conductivity of the mantle. It is shown that a model that includes only the principal P 0 1 term can lead to a seriously misleading internal/external ratio.

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Section: Methods Of Analysissupporting

confidence: 78%

Semi-annual variation of the geomagnetic field

2014

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“…Stening et al (1997b) compared least- squares fitting of a sum of solar and lunar tides to geophysical time series (Malin and Schlapp, 1980) in comparison to methods based on Fourier analysis (Winch and Cunningham, 1972) and concluded that the least-squares method offers a number of advantages. In particular, each hourly data point is treated separately, so scattered and/or missing data is not a problem.…”

Section: Discussionmentioning

confidence: 99%

“…The location of Collm differs in longitude by 17 • from the UK. This difference is accounted for using the analysis method described by Malin and Schlapp (1980) (i.e. the phases, time of maximum, should be directly comparable for the migrating lunar tide).…”

Section: Discussionmentioning

confidence: 99%

Observations of lunar tides in the mesosphere and lower thermosphere at Arctic and middle latitudes

2006

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Abstract. Meteor radars have been used to measure the horizontal winds in the mesosphere and lower thermosphere over Castle Eaton (52 • N) in the UK and over Esrange (68 • N) in Arctic Sweden. We consider a 16-year data set covering the interval 1988-2004 for the UK and a 6-year data set covering the interval 1999-2005 for the Arctic. The signature of the 12.42-h (M 2 ) lunar tide has been identified at both locations. The lunar tide is observed to reach amplitudes as large as 11 ms −1 . The Arctic radar has an interferometer and so allows investigation of the vertical structure of the lunar tide. At both locations the tide has maximum amplitudes in winter with a second autumnal maximum. The amplitude is found to increase with height over the 80-100 km height range observed. Vertical wavelengths are very variable, ranging from about 15 km in summer to more than 60 km in winter. Comparisons with the Vial and Forbes (1994) model reveals generally good agreement, except in the case of the summer vertical wavelengths which are observed to be significantly shorter than predicted.

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“…In 1980, the least-squares method was originally introduced and compared with the method of Chapman-Miller by Malin and Schlapp (1980). Compared with the other lunar tidal analysis method, they found that the least-squares method has several advantages.…”

Section: Discussionmentioning

confidence: 99%

A measurement of the lunar semidiurnal tide at Wuhan (30°40′N, 114°30′E)

et al. 2007

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Upper atmospheric winds have been measured at heights from 80 to 100 km over Wuhan (30 • 40 N, 114 • 30 E), China with a meteor radar from 2002 to 2005. The variations of lunar semidiurnal tidal amplitudes and phases with both seasons and heights are studied in detail to reveal the properties of the lunar semidiurnal tide. It is shown that the lunar semidiurnal tide is stronger in January than other months, and its second peak appears near August. For most months the eastward maximum is 3 ± 1 lunar hours later than the northward maximum, as classical theory predicts for a northern hemisphere tide. The observed seasonal and height variations are also compared with the Global Scale Wave Model (GSWM). The phases do not agree well with those of the GSWM model. The maximum amplitude occurs in a different month in the model. There are about 5 lunar hours phase difference between the observed and the model at 90 and 96 km in eastward and northward components. A comparison of the lunar and solar semidiurnal tides is also shown in this paper. The behavior of these two tides in season is different, especially for the month of appearance of maximum amplitude.

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Geomagnetic lunar analysis by least-squares

Cited by 36 publications

References 8 publications

Semi-annual variation of the geomagnetic field

Semi-annual variation of the geomagnetic field

Observations of lunar tides in the mesosphere and lower thermosphere at Arctic and middle latitudes

A measurement of the lunar semidiurnal tide at Wuhan (30°40′N, 114°30′E)

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