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Wind and Temperature Profiles in the Radix Layer: The Bottom Fifth of the Convective Boundary Layer.

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Title: Wind and Temperature Profiles in the Radix Layer: The Bottom Fifth of the Convective Boundary Layer.
Author: Santoso, Edi; Stull, Roland B.
Issue Date: 1998-06
Publicly Available in cIRcle 2011-04-11
Publisher American Meteorological Society
Citation: Santoso, Edi, Stull,Roland B. 1998. Wind and Temperature Profiles in the Radix Layer: The Bottom Fifth of the Convective Boundary Layer. Journal of Applied Meteorology. 37(6) 545-558. http://journals.ametsoc.org/doi/pdf/10.1175/1520-0450%281998%29037%3C0545%3AWATPIT%3E2.0.CO%3B2
Abstract: In the middle of the convective atmospheric boundary layer is often a deep layer of vertically uniform wind speed (MUL), wind direction, and potential temperature (θUL). A radix layer is identified as the whole region below this uniform layer, which includes the classic surface layer as a shallower subdomain. An empirical wind speed (M) equation with an apparently universal shape exponent (A) is shown to cause observations from the 1973 Minnesota field experiment to collapse into a single similarity profile, with a correlation coefficient of roughly 0.99. This relationship is M/MUL = F(z/zR), where F is the profile function, z is height above ground, and zR is depth of the radix layer. The profile function is F = (z/zR)A exp[A(1 − z/zR)] in the radix layer (z/zR 1), and F = 1 in the uniform layer (zR < z < 0.7zi). The radix-layer equations might be of value for calculation of wind power generation, wind loading on buildings and bridges, and air pollutant transport. The same similarity function F with a different radix-layer depth and shape exponent is shown to describe the potential temperature (θ) profile: (θ − θUL)/(θ0 − θUL) = 1 − F(z/zR), where θ0 is the potential temperature of the air near the surface. These profile equations are applicable from 1 m above ground level to the midmixed layer and include the little-studied region above the surface layer but below the uniform layer. It is recommended that similarity profiles be formulated as mean wind or potential temperature versus height, rather than as shears or gradients versus height because shear expressions disguise errors that are revealed when the shear is integrated to get the speed profile. Copyright [date of publication] American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or copyright@ametsoc.org.
Affiliation: Science, Faculty ofEarth and Ocean Sciences, Department of
URI: http://hdl.handle.net/2429/33512
Peer Review Status: Reviewed
Scholarly Level: Faculty

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