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| Titel |
Functional derivatives applied to error propagation of uncertainties in topography to large-aperture scintillometer-derived heat fluxes |
| VerfasserIn |
M. A. Gruber, G. J. Fochesatto, O. K. Hartogensis, M. Lysy |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 7 ; Nr. 7, no. 7 (2014-07-31), S.2361-2371 |
| Datensatznummer |
250115862
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| Publikation (Nr.) |
 copernicus.org/amt-7-2361-2014.pdf |
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| Zusammenfassung |
| Scintillometer measurements
allow for estimations of the refractive index structure parameter Cn2
over large areas in the atmospheric surface layer. Turbulent fluxes of heat
and momentum are inferred through coupled sets of equations derived from the
Monin–Obukhov similarity hypothesis. One-dimensional sensitivity functions
have been produced that relate the sensitivity of heat fluxes to
uncertainties in single values of beam height over flat terrain. However,
real field sites include variable topography. We develop here, using
functional derivatives, the first analysis of the sensitivity of
scintillometer-derived sensible heat fluxes to uncertainties in spatially
distributed topographic measurements. Sensitivity is shown to be concentrated
in areas near the center of the beam path and where the underlying topography
is closest to the beam height. Relative uncertainty contributions to the
sensible heat flux from uncertainties in topography can reach 20% of the
heat flux in some cases. Uncertainty may be greatly reduced by focusing
accurate topographic measurements in these specific areas. A new
two-dimensional variable terrain sensitivity function is developed for
quantitative error analysis. This function is compared with the previous
one-dimensional sensitivity function for the same measurement strategy over
flat terrain. Additionally, a new method of solution to the set of coupled
equations is produced that eliminates computational error. |
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