Drag coefficient and roughness length determinations on an Alaskan Arctic Coast during summer

1975 ◽  
Vol 8 (2) ◽  
pp. 235-237 ◽  
Author(s):  
C. D. Walters
Keyword(s):  
Drag Coefficient ◽  
Roughness Length ◽  
Arctic Coast ◽  
Alaskan Arctic

Offshore Bars along the Alaskan Arctic Coast

1975 ◽  
Vol 83 (2) ◽  
pp. 209-221 ◽  
Author(s):  
A. D. Short
Keyword(s):  
Arctic Coast ◽  
Alaskan Arctic

scholarly journals Form drag on pressure ridges and drag coefficient in the northwestern Weddell Sea, Antarctica, in winter

2013 ◽  
Vol 54 (62) ◽  
pp. 133-138
Author(s):  
Tan Bing ◽  
Lu Peng ◽  
Li Zhijun ◽  
Li Runling
Keyword(s):  
Sea Ice ◽  
Drag Coefficient ◽  
Roughness Length ◽  
Weddell Sea ◽  
Neutral Stability ◽  
Form Drag ◽  
Laser Altimeter ◽  
Dominant Component ◽  
Elevation Data ◽  
Ice Surfaces

AbstractSurface elevation data for sea ice in the northwesternty - Weddell Sea, Antarctica, collected by a helicopter-borne laser altimeter during the Winter Weddell Outflow Study 2006, were used to estimate the form drag on pressure ridges and its contribution to the total wind drag, and the air-ice drag coefficient at a reference height of 10 m under neutral stability conditions (Cdn(10)). This was achieved by partitioning the total wind drag into two components: form drag on pressure ridges and skin drag over rough sea-ice surfaces. The results reveal that for the compacted ice field, the contribution of form drag on pressure ridges to the total wind drag increases with increasing ridging intensity Ri (where Ri is the ratio of mean ridge height to spacing), while the contribution decreases with increasing roughness length. There is also an increasing trend in the air-ice drag coefficient Cdn(10) as ridging intensity Ri increases. However, as roughness length increases, Cdn(10) increases at lower ridging intensities (Ri < 0.023) but decreases at lower ridging intensities (0.023 < Ri < 0.05). These opposing trends are mainly caused by the dominance of the form drag on pressure ridges and skin drag over rough ice surfaces. Generally, the form drag becomes dominant only when the ridging intensity is sufficiently large, while the skin drag is the dominant component at relatively larger ridging intensities. These results imply that a large value of Cdn(10) is caused not only by the form drag on pressure ridges, but also by the skin drag over rough ice surfaces. Additionally, the estimated drag coefficients are consistent with reported measurements in the northwestern Weddell Sea, further demonstrating the feasibility of the drag partition model.

scholarly journals Relating the Drag Coefficient and the Roughness Length over the Sea to the Wavelength of the Peak Waves

2009 ◽  
Vol 39 (11) ◽  
pp. 3011-3020 ◽  
Author(s):  
Edgar L. Andreas
Keyword(s):  
Dispersion Relation ◽  
Drag Coefficient ◽  
Friction Velocity ◽  
Roughness Length ◽  
Wind Wave ◽  
Wave Spectrum ◽  
Wave Dispersion ◽  
Wave Parameter ◽  
Independent Variables ◽  
Acceleration Of Gravity

Abstract The standard 10-m reference height for computing the drag coefficient over the sea is admittedly arbitrary. The literature contains occasional suggestions that a scaling length based on the wavelength of the peak waves λp is a more natural reference height. Attempts to confirm this hypothesis must be done carefully, however, because of the potential for fictitious correlation between nondimensional dependent and independent variables. With the DMAJ dataset as an example, this study reviews the issue of fictitious correlation in analyses that use λp/2 as the reference height for evaluating the drag coefficient and that use kp (=2π/λp) as a scale for the roughness length z0. (The DMAJ dataset is a compilation of four individual datasets; D, M, A, and J, respectively, identify the lead authors of the four studies: Donelan, Merzi, Anctil, and Janssen.) This dataset has been used in several previous studies to evaluate the dependence of kpz0 and the drag coefficient evaluated at λp/2 on the nondimensional wave parameter ω* = ωpu*/g. Here ωp is the radian frequency of the peak in the wind–wave spectrum, u* is the friction velocity, and g is the acceleration of gravity. Because the DMAJ dataset does not, however, include independent measurements of λp and ωp, λp had to be inferred from measurements of ωp through the wave dispersion relation. The presence of ωp in both the dependent and independent variables, therefore, exacerbates the fictitious correlation. One conclusion, thus, is that using λp to formulate the drag coefficient and the nondimensional roughness length as functions of a nondimensional variable that includes ωp requires a dataset with independent measurements of λp and ωp.

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