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| Titel |
A new method for measuring the imaginary part of the atmospheric refractive index structure parameter in the urban surface layer |
| VerfasserIn |
R. Yuan, T. Luo, J. Sun, Z. Zeng, C. Ge, Y. Fu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 5 ; Nr. 15, no. 5 (2015-03-06), S.2521-2531 |
| Datensatznummer |
250119498
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| Publikation (Nr.) |
 copernicus.org/acp-15-2521-2015.pdf |
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| Zusammenfassung |
| The atmospheric refractive index consists of both real and imaginary parts.
The intensity of refractive index fluctuations is generally expressed as the
refractive index structure parameter, with the real part reflecting the
strength of atmospheric turbulence and the imaginary part reflecting
absorption in the light path. A large aperture scintillometer (LAS) is often
used to measure the structure parameter of the real part of the atmospheric
refractive index, from which the sensible and latent heat fluxes can further
be obtained, whereas the influence of the imaginary part is ignored or
considered noise. In this theoretical analysis study, the relationship
between logarithmic light intensity variance and the atmospheric refractive
index structure parameter (ARISP), as well as that between the logarithmic
light intensity structure function and the ARISP, is derived. Additionally,
a simple expression for the imaginary part of the ARISP is obtained which
can be conveniently used to determine the imaginary part of the ARISP from
LAS measurements. Moreover, these relationships provide a new method for
estimating the outer scale of turbulence. Light propagation experiments were
performed in the urban surface layer, from which the imaginary part of the
ARISP was calculated. The experimental results showed good agreement with
the presented theory. The results also suggest that the imaginary part of
the ARISP exhibits a different diurnal variation from that of the real part.
For the wavelength of light used (0.62 μm), the variation of the imaginary
part of the ARISP is related to both the turbulent transport process and the
spatial distribution characteristics of aerosols. |
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