Analysis of microphysical processes in fog

Yunlong Li, Peter Hoogeboom, Herman W.J. Russchenberg, H Klein Baltink

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

Abstract

The microphysical processes in fog are examined based on an analysis of four fog events captured by the in-situ and remote sensing synergy at the Cabauw Experimental Site for Atmospheric Research (CESAR) in the western part of the Netherlands. A 35 GHz cloud radar at CESAR has been used in "fog mode" for the first time in the campaign. In this paper, the microphysical parameterization of fog is first introduced as the basis for analyzing the microphysical processes in the lifecycle of fog. The general microphysical characteristics of the four fog events are studied and key microphysical parameters (droplet number concentration, liquid water content, mean radius, and spectral standard deviation) related to fog are found lower than those in other sites due to the low aerosol concentration at Cabauw. The dominant processes in fog are investigated from the relationships among the key microphysical parameters. The positive correlations of each two parameters in lifecycle stages of a stratus-fog case suggest the dominant scheme in fog is droplet activation with subsequent hygroscopic growth and/or droplet evaporation, which is also supported by the combined observations of visibility and radar reflectivity. The shape of fog drop size distribution regularly broadens and then narrows in the whole lifecycle. However, other mechanisms could exist, although not dominating. Collision-coalescence is a significant factor for the continued growth of big fog droplets when they have reached certain sizes in the mature stage. In the datasets, the collision-coalescence process could be distinguished from the unusual negative correlations among the key microphysical parameters in the lifecycle of another stratus-fog case, and the temporal evolutions of droplet number concentration, mean radius, spectra width, visibility and radar reflectivity show the evidence of it.

Original languageEnglish
Title of host publicationRemote Sensing of Clouds and the Atmosphere XIX; and Optics in Atmospheric Propagation and Adaptive Systems XVII
PublisherSPIE
Number of pages11
Volume9242
ISBN (Electronic)9781628413052
DOIs
Publication statusPublished - 2014
EventRemote Sensing of Clouds and the Atmosphere XIX; and Optics in Atmospheric Propagation and Adaptive Systems XVII - Amsterdam, Netherlands
Duration: 22 Sep 201425 Sep 2014

Conference

ConferenceRemote Sensing of Clouds and the Atmosphere XIX; and Optics in Atmospheric Propagation and Adaptive Systems XVII
CountryNetherlands
CityAmsterdam
Period22/09/1425/09/14

Keywords

  • collision-coalescence process
  • dominant process
  • fog
  • microphysical parameters
  • microphysical processes
  • microphysical relationships
  • radar reflectivity
  • visibility

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  • Cite this

    Li, Y., Hoogeboom, P., Russchenberg, H. W. J., & Klein Baltink, H. (2014). Analysis of microphysical processes in fog. In Remote Sensing of Clouds and the Atmosphere XIX; and Optics in Atmospheric Propagation and Adaptive Systems XVII (Vol. 9242). [924217] SPIE. https://doi.org/10.1117/12.2067175