The Life Cycle of Valley Fog. Part I: Micrometeorological Characteristics

Pilié, R. J.; Mack, E. J.; Kocmond, W. C.; Rogers, C. W.; Eadie, W. J.

doi:10.1175/1520-0450(1975)014<0347:tlcovf>2.0.co;2

Cited by 77 publications

(48 citation statements)

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“…There are many observations of physical properties of radiation fogs such as Fleagle et al (1952), Toyooka Observatory of Osaka Branch, Japan Meteorological Agency (JMA) (1954), Okita (1962), Pilie et at. (1975), and Roach et al (1976).…”

Section: Introductionsupporting

confidence: 92%

A Numerical Study of the Formation and the Dissipation of Radiation Fogs

Ohta

Tanaka

1986

Journal of the Meteorological Society of Japan

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The evolution of radiation fog has been investigated by numerical simulations. A onedimensional boundary layer model was adopted for the atmosphere.No moisture transport in the soil layer was assumed; the dew and falling droplets are assumed to be stored at the ground surface.The P3-approximation method was employed to incorporate the effect of radiative transfer into the boundary layer model.With the development of radiation fog, the radiative cooling rate increases greatly and temperature decreases rapidly just below the fog top. This effect accelerates the condensation of water vapor near the fog top and, consequently, increases the height and liquid water content of the fog. The sudden increase of downward radiative flux from the fog layer enhances the rise of surface temperature, and the temperature profile in the fog layer turns from stable into unstable.With the increase of instability of temperature stratification in the fog layer, eddy diffusivities also increase rapidly. This effect enhances the transport of water vapor from the surface to the fog layer, and the development of the fog is again accelerated.In contrast to that within the fog layer, the temperature profile above the fog layer remains stable; consequently a sharp temperature inversion appears near the fog top. The height of this inversion rises gradually as the height of the fog top increases. When the moisture stored on the ground surface is exhausted and the transport of water vapor from the surface to the fog layer vanishes, the surface temperature rises suddenly and fog begins to disappear from the lowest layer near the ground.

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Section: Introductionsupporting

confidence: 92%

A Numerical Study of the Formation and the Dissipation of Radiation Fogs

Ohta

Tanaka

1986

Journal of the Meteorological Society of Japan

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“…With the beginning of the dissipation stage all three parameters decrease again. If one expands the three-stage classification by another phase that takes place right before the actual fog event, one gets the PFM (Pilie´et al, 1972(Pilie´et al, , 1975a(Pilie´et al, , 1975b. The so-called ground fog or prefog phase in the PFM starts when VIS B4 km and lasts until VIS B1 km for the first time.…”

Section: Discussionmentioning

confidence: 89%

“…Even though the separation of the investigated fog events in three evolutionary stages seems to be appropriate, featuring the same main trends in the microphysics as the GFM and the PFM; Pilie´'s criteria (Pilie´et al, 1972(Pilie´et al, , 1975a(Pilie´et al, , 1975b for stage classification as minimum VIS or maximum values of microphysical properties did not match with the statistical based CPs of the three observed fog events.…”

Section: Differentiation Of Fog Life Cycle Phasesmentioning

confidence: 99%

“…The balance between radiative cooling and turbulent mixing seems to be a primary factor in the development of radiation fog Nakanishi, 2000;Terradellas and Bergot, 2008). Beside radiative cooling as a main mechanism the upward soil heat flux, as well as the warming effects and moisture losses through dew deposition from turbulent mixing, strongly influence the formation, structure and life cycle of radiation fog (Lala et al, 1975;Pilie´et al, 1975b;Brown and Roach, 1976;Findlater, 1985;Turton and Brown, 1987;Fitzjarrald and Lala, 1989;Bergot and Gue´dalia, 1994;Duynkerke, 1999).…”

Section: Introductionmentioning

confidence: 99%

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Development and application of a method for the objective differentiation of fog life cycle phases

Maier

Bendix

Thies

2013

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T An objective classification of radiation fog in distinct evolutionary stages during its life cycle based on reliable criteria is essential for various applications, for example for numerical fog modelling and fog forecasting. However, there have been Á up to now Á merely qualitative approaches for the distinction of different evolutionary stages in radiation fog. Measurements of the microphysical fog properties with an optical particle counter obtained from droplet measurement technologies together with recordings of the horizontal visibility (VIS) are statistically analyzed to determine individual evolutionary stages of radiation fog with consistent microphysical properties. The developed three-stage approach is based on a statistical change point analysis of the double sum curves of the VIS, the liquid water content, the droplet concentration and the mean radius of the drop size distributions. It could be shown that each of the three recorded radiation fog occurrences could be split into three consecutive phases from formation to dissipation, regardless whether the VIS or the microphysical properties were considered. Having featured consistent microphysical patterns, it could be assumed that the three separated phases of the single fog occurrence could be aggregated for radiation fog. Although this classification is statistically reliable, the dataset still has to be extended for a generalization concerning the separated evolutionary stages.

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“…This suggests that the processes involved in the reduction of the CDNC in a radiative fog are as efficient as the entrainment-mixing occurring in cumulus clouds. Note that many studies (Pilié et al, 1975;Choularton et al, 1981;Gerber, 13 Atmos. Chem.…”

Section: Impact Of Ccn Concentration On Fog Microstructurementioning

confidence: 99%

Experimental study of the aerosol impact on fog microphysics

Mazoyer

Burnet

Roberts

et al. 2016

Preprint

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Abstract.Comprehensive field campaigns dedicated to fog life cycle observation were conducted during the winters of [2010][2011][2012][2013] at the SIRTA observatory in the suburb of Paris. In order to document their properties, in situ microphysical measurements collected during 23 fog events are examined here. They reveal large variability in number, concentration and size of both aerosol background before the fog onset and fog droplets according to the different cases. The objective of this paper is to 5 evaluate the impact of aerosol particles on the fog microphysics.To derive an accurate estimation of the actual activated fog droplet number concentration N act, we determine the hygroscopicity parameter κ, the dry and the wet critical diameter and the critical supersaturation for each case by using an iterative procedure based on the κ-Köhler theory that combines cloud condensation nuclei (CCN), dry particle and droplet size distribution measurements. Resulting values of κ = 0.17 ± 0.05 were found typical of continental aerosols. Our study reveals No detectable trend between the concentration of aerosol particles with diameter > 200 nm and N act was observed. In contrast the CCN data at 0.1 % supersaturation exhibits a strong correlation with these aerosol concentrations. We therefore 15 conclude that the actual supersaturations reached during these fog episodes are too low and no simultaneous increase of aerosols > 200 nm and droplet concentrations can be observed. Moreover our analysis suggests that a high aerosol loading limits the supersaturation values. It is also found that the activated fraction mainly depends on the aerosol size while the hygroscopicity appears to be of a secondary importance.Although radiative fogs are usually associated with higher aerosol loading rather than to stratus lowering events, our analysis 20 reveals that the activated particle concentrations at the beginning of the event are similar for both types of fog. However the evolution of the droplet concentration during the fog life cycle shows significant differences between both types of fog.

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The Life Cycle of Valley Fog. Part I: Micrometeorological Characteristics

Cited by 77 publications

References 0 publications

A Numerical Study of the Formation and the Dissipation of Radiation Fogs

A Numerical Study of the Formation and the Dissipation of Radiation Fogs

Development and application of a method for the objective differentiation of fog life cycle phases

Experimental study of the aerosol impact on fog microphysics

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