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- Sjöblom, Anna, et al.
(författare)
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Comparison Between Eddy-Correlation and Inertial Dissipation Methods in the Marine Atmospheric Surface Layer
- 2004
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Ingår i: Boundary-layer Meteorology. - 0006-8314 .- 1573-1472. ; 110:2, s. 141-164
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Tidskriftsartikel (refereegranskat)abstract
- A comparison of momentum fluxes determined by the eddy-correlation method(ECM) and the inertial dissipation method (IDM) has been performed using longterm measurements over the sea. The measurements were made on the island ofÖstergarnsholm in the middle of the Baltic Sea. The results show that a`classical' form of the inertial dissipation method, i.e., assuming that the transportterms are negligible, and using an effective value for the Kolmogorov constant of0.55, can be used with a mean relative difference between the two methods of about15% for -1 < z/L < 0.5 (z being height and L the Obukhov length). The IDMmethod works best for high wind speeds and neutral conditions. For low windspeeds (U < 6 m s-1) the relation between the two methods is morecomplex. IDM then gives higher values than ECM on the average (about 20%),especially for swell conditions, indicating the need for an imbalance function inthe turbulent kinetic energy budget. Calculations of the effective Kolmogorovconstant, αa, suggest a dependence upon the wave age, αa increasing with increasing wave age, where the value 0.59 fits the data well for saturated waves.
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| 2. |
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| 3. |
- Sjöblom, Anna, et al.
(författare)
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Vertical Structure in the Marine Atmospheric Boundary Layer and its Implication for the Inertial Dissipation Method
- 2003
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Ingår i: Boundary-layer Meteorology. - 0006-8314 .- 1573-1472. ; 109:1, s. 1-25
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the marine atmospheric boundarylayer and the validity ofMonin–Obukhov similarity theory over the seahave been investigated using longterm measurements. Three levels of turbulencemeasurements (at 10 m, 18 mand 26 m) at Östergarnsholm in themiddle of the Baltic Sea have beenanalysed. The results show that turbulentparameters have a strong dependenceon the actual height due to wave influence.The wind profile and thus thenormalised wind gradient are very sensitiveto wave state. The lower part of theboundary layer can be divided into three heightlayers, a wave influenced layerclose to the surface, a transition layer andan undisturbed ‘ordinary’ surfacelayer; the depth of the layers is determinedby the wave state. This heightstructure can, however, not be found for thenormalised dissipation, which is onlya function of the stability, except duringpronounced swell where the actualheight also has to be accounted for. Theresults have implications for the heightvariation of the turbulent kinetic energy(TKE) budget. Thus, the imbalancebetween production and dissipation willalso vary with height according to thevariation of wave state. This, in turn,will of course have strong implicationsfor the inertial dissipation method, inwhich a parameterisation of the TKEbudget is used.
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| 7. |
- Källstrand, Birgitta, et al.
(författare)
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Mesoscale wind field modifications over the Baltic Sea
- 2000
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Ingår i: BOUNDARY-LAYER METEOROLOGY. - 0006-8314. ; 95:2, s. 161-188
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Tidskriftsartikel (refereegranskat)abstract
- For two consecutive days during spring 1997, the wind field over the Baltic Sea has been studied. The strength of the geostrophic wind speed is the major difference in synoptic conditions between these two days. During both days, the mesoscale wind field
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