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| Titel |
A new method to measure Bowen ratios using high-resolution vertical dry and wet bulb temperature profiles |
| VerfasserIn |
T. Euser, W. M. J. Luxemburg, C. S. Everson, M. G. Mengistu, A. D. Clulow, W. G. M. Bastiaanssen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 6 ; Nr. 18, no. 6 (2014-06-03), S.2021-2032 |
| Datensatznummer |
250120372
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| Publikation (Nr.) |
 copernicus.org/hess-18-2021-2014.pdf |
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| Zusammenfassung |
| The Bowen ratio surface energy balance method is a relatively simple method
to determine the latent heat flux and the actual land surface evaporation.
The Bowen ratio method is based on the measurement of air temperature and
vapour pressure gradients. If these measurements are performed at only two
heights, correctness of data becomes critical. In this paper we present the
concept of a new measurement method to estimate the Bowen ratio based on
vertical dry and wet bulb temperature profiles with high spatial resolution.
A short field experiment with distributed temperature sensing (DTS) in a
fibre optic cable with 13 measurement points in the vertical was undertaken.
A dry and a wetted section of a fibre optic cable were suspended on a 6 m
high tower installed over a sugar beet trial plot near Pietermaritzburg
(South Africa). Using the DTS cable as a psychrometer, a near continuous
observation of vapour pressure and air temperature at 0.20 m intervals was
established. These data allowed the computation of the Bowen ratio with a
high spatial and temporal precision. The daytime latent and sensible heat
fluxes were estimated by combining the Bowen ratio values from the DTS-based
system with independent measurements of net radiation and soil heat flux. The
sensible heat flux, which is the relevant term to evaluate, derived from the
DTS-based Bowen ratio (BR-DTS) was compared with that derived from co-located
eddy covariance (R2 = 0.91), surface layer scintillometer
(R2 = 0.81) and surface renewal (R2 = 0.86) systems. By using
multiple measurement points instead of two, more confidence in the derived Bowen
ratio values is obtained. |
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