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Estimating fog-top height through near-surface micrometeorological measurements

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Román Cascón, Carlos and Yagüe Anguis, Carlos and Steeneveld, Gert-Jan and Sastre Marugán, Mariano and Arrillaga, Jon Ander and Maqueda Burgos, Gregorio (2016) Estimating fog-top height through near-surface micrometeorological measurements. Atmospheric research, 170 . pp. 76-86. ISSN 0169-8095

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Official URL: http://dx.doi.org/10.1016/j.atmosres.2015.11.016




Abstract

Fog-top height (fog thickness) is very useful information for aircraft maneuvers, data assimilation/validation of Numerical Weather Prediction models or nowcasting of fog dissipation. This variable is usually difficult to determine, since the fog-layer top cannot be observed from the surface. In some cases, satellite data, ground remote sensing instruments or atmospheric soundings are used to provide approximations of fog-top height. These instruments are expensive and their data not always available. In this work, two different methods for the estimation of fog-top height from field measurements are evaluated from the statistical analysis of several radiation-fog events at two research facilities. Firstly, surface friction velocity and buoyancy flux are here presented as potential indicators of fog thickness, since a linear correlation between fog thickness and surface turbulence is found at both sites. An operational application of this method can provide a continuous estimation of fog-top height with the deployment of a unique sonic anemometer at surface. Secondly, the fog-top height estimation based on the turbulent homogenisation within well-mixed fog (an adiabatic temperature profile) is evaluated. The latter method provides a high percentage of correctly-estimated fog-top heights for well-mixed radiation fog, considering the temperature difference between different levels of the fog. However, it is not valid for shallow fog (~ less than 50 m depth), since in this case, the weaker turbulence within the fog is not able to erode the surface-based temperature inversion and to homogenise the fog layer.


Item Type:Article
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© 2015 Elsevier B.V.
This research has been funded by the Spanish Government (MINECO project CGL2012-37416-C04-02 and grant BES-2013 064585). The GR3/14 program (supported by UCM and Banco Santander) has also partially financed this work through the Research Group Micrometeorology and Climate Variability (No. 910437). Part of this work has been completed during a scientific stay of Carlos Román Cascón in Wageningen University through a WIMEK Research Fellowship. The contribution by G.J. Steeneveld has partly been sponsored by the NWO contract 863.10.010 (Lifting the fog). We would like to thank KNMI, especially Dr. Fred Bosveld for making CESAR observations available and Dr. Peláez and Prof. Casanova for allowing us access to CIBA facilities. The authors would like to thank the two anonymous reviewers for their helpful comments, which have improved the quality and clarity of the paper.

Uncontrolled Keywords:Radiation fog; Ground fog; Layer; Stratus; Event; Feasibility; Simulation; Prediction; Airport; Models
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:36451
Deposited On:30 Mar 2016 14:53
Last Modified:10 Dec 2018 15:04

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