Fogwater deposition modeling for terrestrial ecosystems: A review of developments and measurements

Katata, Genki

doi:10.1002/2014jd021669

Cited by 52 publications

(56 citation statements)

References 155 publications

(390 reference statements)

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“…By analogy with dry deposition, it would also be better to take droplet diameter into account. Other studies have also shown that fog water deposition is strongly enhanced at the forest edge, becoming up to 1.5-4 times larger than that in closed forest canopies (Katata, 2014), so it could be interesting to simulate the edge effect of fog water deposition. It is also crucial to perform measurements of fog water deposition and dewfall during field experiments (Price and Clark, 2014).…”

Section: Resultsmentioning

confidence: 99%

“…In a review based on measurements and parameterization, Katata (2014) showed that V DEP values ranged from 2.1 to 8.0 cm s −1 for short vegetation. Here V DEP is assumed to be constant, equal to 2 cm s −1 .…”

Section: Presentation Of the Modelmentioning

confidence: 99%

“…The second one, called NDG, removed deposition altogether. The third one, noted DE8, considered a deposition velocity V DEP of 8 cm s −1 over grass and trees, which is the upper bound given by Katata (2014) instead of 2 cm s −1 as in REF.…”

Section: Impact Of Depositionmentioning

confidence: 99%

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Large eddy simulation of radiation fog: impact of dynamics on the fog life cycle

et al. 2017

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Abstract. Large eddy simulations (LESs) of a radiation fog event occurring during the ParisFog experiment are studied with a view to analyse the impact of the dynamics of the boundary layer on the fog life cycle. The LES, performed with the Meso-NH model at 5 m resolution horizontally and 1 m vertically, and with a 2-moment microphysical scheme, includes the drag effect of a tree barrier and the deposition of droplets on vegetation. The model shows good agreement with measurements of near-surface dynamic and thermodynamic parameters and liquid water path. The blocking effect of the trees induces elevated fog formation, as actually observed, and horizontal heterogeneities during the formation. It also limits cooling and cloud water production. Deposition is found to exert the most significant impact on fog prediction as it not only erodes the fog near the surface but also modifies the fog life cycle and induces vertical heterogeneities. A comparison with the 2 m horizontal resolution simulation reveals small differences, meaning that grid convergence is achieved. Conversely, increasing numerical diffusion through a wind advection operator of lower order leads to an increase in the liquid water path and has a very similar effect to removing the tree barrier. This study allows us to establish the major dynamical ingredients needed to accurately represent the fog life cycle at very high-resolution.

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Section: Resultsmentioning

confidence: 99%

Section: Presentation Of the Modelmentioning

confidence: 99%

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Large eddy simulation of radiation fog: impact of dynamics on the fog life cycle

et al. 2017

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“…Entrainment of warmer, unsaturated air from above the fog is therefore enabled, which will cause evaporation as it mixes with the fog (Gultepe et al, 2007). At the same time, turbulent eddies near the surface can deposit droplets onto the vegetation (Katata, 2014), and droplets transported downwards can evaporate when approaching the warmer surface (Nakanishi, 2000). In addition to vertical destabilisation, the wind shear can contribute significantly to the generation of turbulence in fog (Mason, 1982;Nakanishi, 2000;Bergot, 2013).…”

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confidence: 99%

Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing

Wærsted¹,

Haeffelin

Dupont

et al. 2017

Atmos. Chem. Phys.

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Abstract. Radiative cooling and heating impact the liquid water balance of fog and therefore play an important role in determining their persistence or dissipation. We demonstrate that a quantitative analysis of the radiation-driven condensation and evaporation is possible in real time using groundbased remote sensing observations (cloud radar, ceilometer, microwave radiometer). Seven continental fog events in midlatitude winter are studied, and the radiative processes are further explored through sensitivity studies. The longwave (LW) radiative cooling of the fog is able to produce 40-70 g m −2 h −1 of liquid water by condensation when the fog liquid water path exceeds 30 g m −2 and there are no clouds above the fog, which corresponds to renewing the fog water in 0.5-2 h. The variability is related to fog temperature and atmospheric humidity, with warmer fog below a drier atmosphere producing more liquid water. The appearance of a cloud layer above the fog strongly reduces the LW cooling relative to a situation with no cloud above; the effect is strongest for a low cloud, when the reduction can reach 100 %. Consequently, the appearance of clouds above will perturb the liquid water balance in the fog and may therefore induce fog dissipation. Shortwave (SW) radiative heating by absorption by fog droplets is smaller than the LW cooling, but it can contribute significantly, inducing 10-15 g m −2 h −1 of evaporation in thick fog at (winter) midday. The absorption of SW radiation by unactivated aerosols inside the fog is likely less than 30 % of the SW absorption by the water droplets, in most cases. However, the aerosols may contribute more significantly if the air mass contains a high concentration of absorbing aerosols. The absorbed radiation at the surface can reach 40-120 W m −2 during the daytime depending on the fog thickness. As in situ measurements indicate that 20-40 % of this energy is transferred to the fog as sensible heat, this surface absorption can contribute significantly to heating and evaporation of the fog, up to 30 g m −2 h −1 for thin fog, even without correcting for the typical underestimation of turbulent heat fluxes by the eddy covariance method. Since the radiative processes depend mainly on the profiles of temperature, humidity and clouds, the results of this paper are not site specific and can be generalised to fog under different dynamic conditions and formation mechanisms, and the methodology should be applicable to warmer and moister climates as well. The retrieval of approximate emissivity of clouds above fog from cloud radar should be further developed.

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“…Besides, acidic fogs are directly related to forest decline (Schemenauer, 1986;Pandis et al, 1990;Barker and Ashenden, 1992;Cape, 1993;Igawa et al, 2002). Fog water deposition could also explain some of the differences in soil contamination between deposition models and fields observations after the Fukushima accident (Katata, 2014;Hososhima and Kaneyasu, 2015). Deposition rate and deposition velocity values can be directly incorporated in operational models used in emergency situations.…”

Section: Introductionmentioning

confidence: 99%

Determination of Fog-Droplet Deposition Velocity from a Simple Weighing Method

Tav

Burnet

Paulat

et al. 2018

Aerosol Air Qual. Res.

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Fog water deposition can represent an important part of the atmospheric water, nutrient and pollutant inputs in specific areas such as mountainous or coastal regions (Shimadera et al., 2011). In order to determine the potential of fog water deposition on plants, a field experiment has been performed in the northeast of France to determine fog droplet deposition velocity on different types of plants. The main objective is to improve deposition models by enabling them to accurately account for water inputs from fog or low clouds at ground level.The flux of deposited fog water was estimated by exposing plants to fog and weighing them with a precision balance. Contrary to other flux measurement methods, the weighing method is simple to set up. Three plant types (small conifers, grass and cabbages) plus bare soil were used as impaction and deposition surfaces. A Particulate Volume Monitor (PVM-100) provided the liquid water content (LWC) to calculate fog droplet deposition velocities, and a Fog Monitor (FM-120), the characterization of the droplet size distribution.Two fog events with different features (visibility, LWC and droplet number) were compared with regard to deposition velocity.When wind speed was below 4 m s -1 , mean fog droplet deposition velocities ranged from less than 2.2 cm s -1 on bare soil to 40 cm s -1 on cypress. Thus, the impaction of fog droplets can be an important part of fog water deposition on plants.

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Fogwater deposition modeling for terrestrial ecosystems: A review of developments and measurements

Cited by 52 publications

References 155 publications

Large eddy simulation of radiation fog: impact of dynamics on the fog life cycle

Large eddy simulation of radiation fog: impact of dynamics on the fog life cycle

Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing

Determination of Fog-Droplet Deposition Velocity from a Simple Weighing Method

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