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| Titel |
Estimating the atmospheric boundary layer height over sloped, forested terrain from surface spectral analysis during BEARPEX |
| VerfasserIn |
W. Choi, I. C. Faloona, M. McKay, A. H. Goldstein, B. Baker |
| 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 ; 11, no. 14 ; Nr. 11, no. 14 (2011-07-18), S.6837-6853 |
| Datensatznummer |
250009918
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| Publikation (Nr.) |
 copernicus.org/acp-11-6837-2011.pdf |
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| Zusammenfassung |
| The atmospheric boundary layer (ABL) height (zi) over complex, forested
terrain is estimated based on the power spectra and the integral length
scale of cross-stream winds obtained from a three-axis sonic anemometer
during the two summers of the BEARPEX (Biosphere Effects on Aerosol and
Photochemistry) Experiment. The zi values estimated with this technique
show very good agreement with observations obtained from balloon tether
sondes (2007) and rawinsondes (2009) under unstable conditions (z/L < 0) at
the coniferous forest in the California Sierra Nevada. On the other hand,
the low frequency behavior of the streamwise upslope winds did not exhibit
significant variations and was therefore not useful in predicting boundary
layer height. The behavior of the nocturnal boundary layer height (h) with
respect to the power spectra of the v-wind component and temperature under
stable conditions (z/L > 0) is also presented. The nocturnal boundary layer
height is found to be fairly well predicted by a recent interpolation
formula proposed by Zilitinkevich et al. (2007), although it was observed to
only vary from 60–80 m during the 2009 experiment in which it was measured.
Finally, significant directional wind shear was observed during both day and
night soundings. The winds were found to be consistently backing from the
prevailing west-southwesterlies within the ABL (the anabatic cross-valley
circulation) to southerlies in a layer ~1–2 km thick just above the
ABL before veering to the prevailing westerlies further aloft. This shear
pattern is shown to be consistent with the forcing of a thermal wind driven
by the regional temperature gradient directed east-southeast in the lower
troposphere. |
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