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| Sodemann, H; Foken, T: Empirical evaluation of an extended similarity theory for the stably stratified atmospheric surface layer, Quarterly Journal of the Royal Meteorological Society, 130, 2665-2671 (2004) | |
| Key words: Antarctica,Brunt-Väisälä frequency,Monin-Obokhov similarity theory,surface layer parameterization |
Abstract:
The theory of the atmospheric stable boundary layer (SBL) has recently been extended by a distinction between nocturnal and long-lived SBLs. The latter SBL type, which includes influences from the free atmosphere on fluxes in the surface layer, requires a modification of the traditional Monin-Obukhov similarity theory. In the present study the applicability of this extended theory for long-lived SBLs is evaluated and the required coefficients are estimated using data from Antarctica.
Changes in wind and temperature gradients due to different weather conditions are shown to exert a strong influence on the estimation of the new coefficients CuN and CΘN. Using the wind gradient as classification criterion, the momentum flux coefficient CuN is estimated to range between 0:51 ± 0:03 and 2:26 ± 0:08. Using the temperature gradient as classification criterion, the heat flux coefficient CΘN is estimated to range between 0:022 ± 0:002 and 0:040 ± 0:001.
At present, the proposed new scaling theory is still in a preliminary stage. Possible future improvement should take into account factors influencing the wind and temperature gradients, such as weather conditions. An artificial background correlation strongly imprints upon the parameter estimation, suggesting that the both the methodology for estimating the new coefficients CuN and CΘN and the choice of the nondimensional variables for this extended scaling theory may require some revision. |
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