Abstract
In unstable conditions, the set of equations defining the aerodynamic resistance to sensible heat transfer, r a , cannot be solved analytically. An iterative technique must be used to obtain r a exactly, but this is cumbersome and time consuming. In this paper, a new, empirical equation is presented relating the ratio, Q, of the aerodynamic resistances in neutral and unstable conditions, to the bulk Richardson number, Ri B . The equation takes the form Q = a + b(−Riβ)c, where a, b and c are empirical functions of (z − d)/z om . This model is shown to predict r awith a mean absolute error of 0.06 s m−1 over the ranges -15 < Ri B < 0 and 10 < (z − d)/z om < 2300. Statistical comparison with other equations that have been proposed for r a in unstable conditions indicates the superior precision of the model presented here.
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Viney, N.R. An empirical expression for aerodynamic resistance in the unstable boundary layer. Boundary-Layer Meteorol 56, 381–393 (1991). https://doi.org/10.1007/BF00119213
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DOI: https://doi.org/10.1007/BF00119213