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| Titel |
Momentum flux determination using the multi-beam Poker Flat Incoherent Scatter Radar |
| VerfasserIn |
M. J. Nicolls, D. C. Fritts, D. Janches, C. J. Heinselman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 30, no. 6 ; Nr. 30, no. 6 (2012-06-11), S.945-962 |
| Datensatznummer |
250017234
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| Publikation (Nr.) |
 copernicus.org/angeo-30-945-2012.pdf |
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| Zusammenfassung |
| In this paper, we develop an estimator for the vertical flux of horizontal
momentum with arbitrary beam pointing, applicable to the case of arbitrary
but fixed beam pointing with systems such as the Poker Flat Incoherent
Scatter Radar (PFISR). This method uses information from all available beams
to resolve the variances of the wind field in addition to the vertical flux
of both meridional and zonal momentum, targeted for high-frequency wave
motions. The estimator utilises the full covariance of the distributed
measurements, which provides a significant reduction in errors over the
direct extension of previously developed techniques and allows for the
calculation of an error covariance matrix of the estimated quantities. We
find that for the PFISR experiment, we can construct an unbiased and robust
estimator of the momentum flux if sufficient and proper beam orientations are
chosen, which can in the future be optimized for the expected frequency
distribution of momentum-containing scales. However, there is a potential
trade-off between biases and standard errors introduced with the new
approach, which must be taken into account when assessing the momentum
fluxes. We apply the estimator to PFISR measurements on 23 April 2008 and 21
December 2007, from 60–85 km altitude, and show expected results as compared
to mean winds and in relation to the measured vertical velocity variances. |
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