RT Journal Article T1 Estimating fog-top height through near-surface micrometeorological measurements A1 Román Cascón, Carlos A1 Yagüe Anguis, Carlos A1 Steeneveld, Gert-Jan A1 Sastre Marugán, Mariano A1 Arrillaga, Jon Ander A1 Maqueda Burgos, Gregorio AB 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. PB Elsevier Science INC SN 0169-8095 YR 2016 FD 2016-03-15 LK https://hdl.handle.net/20.500.14352/24390 UL https://hdl.handle.net/20.500.14352/24390 LA eng NO © 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. NO Ministerio de Economía y Competitividad (MINECO), España NO GR3/14 program (UCM-BSCH) NO Wageningen Institute for Environment and Climate Research (WIMEK), Holanda NO NWO Funding (Netherlands Organisation for Health Research and Development), Holanda NO Universidad Complutense de Madrid (UCM) NO Banco Santander Central Hispano (BSCH) DS Docta Complutense RD 6 abr 2025