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| Titel |
On the parameterization of turbulent fluxes over the tropical Eastern Pacific |
| VerfasserIn |
G. B. Raga, S. Abarca |
| 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 ; 7, no. 3 ; Nr. 7, no. 3 (2007-02-09), S.635-643 |
| Datensatznummer |
250004554
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| Publikation (Nr.) |
 copernicus.org/acp-7-635-2007.pdf |
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| Zusammenfassung |
| We present estimates of turbulent fluxes of heat and momentum derived from
low level (~30 m) aircraft measurements over the tropical Eastern
Pacific and provide empirical relationships that are valid under high wind
speed conditions (up to 25 ms−1). The estimates of total momentum flux
and turbulent kinetic energy can be represented very accurately
(r2=0.99, when data are binned every 1 ms−1) by empirical fits
with a linear and a cubic terms of the average horizontal wind speed. The
latent heat flux shows a strong quadratic dependence on the horizontal wind
speed and a linear relationship with the difference between the air specific
humidity and the saturated specific humidity at the sea surface, explaining
96% of the variance. The estimated values were used to evaluate the
performance of three currently used parameterizations of turbulence fluxes,
varying in complexity and computational requirements. The comparisons with
the two more complex parameterizations show good agreement between the
observed and parameterized latent heat fluxes, with less agreement in the
sensible heat fluxes, and one of them largely overestimating the momentum
fluxes. A third, very simple parameterization shows a surprisingly good
agreement of the sensible heat flux, while momentum fluxes are again
overestimated and a poor agreement was observed for the latent heat flux
(r2=0.62). The performance of all three parameterizations deteriorates
significantly in the high wind speed regime (above 10–15 ms−1). The
dataset obtained over the tropical Eastern Pacific allows us to derive
empirical functions for the turbulent fluxes that are applicable from 1 to
25 ms−1, which can be introduced in meteorological models under high
wind conditions. |
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