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DOI | 10.5194/acp-17-10811-2017 |
Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing | |
Waersted, Eivind G.1; Haeffelin, Martial2; Dupont, Jean-Charles3; Delanoe, Julien4; Dubuisson, Philippe5 | |
2017-09-14 | |
发表期刊 | ATMOSPHERIC CHEMISTRY AND PHYSICS |
ISSN | 1680-7316 |
EISSN | 1680-7324 |
出版年 | 2017 |
卷号 | 17期号:17 |
文章类型 | Article |
语种 | 英语 |
国家 | France |
英文摘要 | 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 ground-based remote sensing observations (cloud radar, ceilometer, microwave radiometer). Seven continental fog events in mid-latitude winter are studied, and the radiative processes are further explored through sensitivity studies. The long-wave (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 gm(-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. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000410638400001 |
WOS关键词 | LARGE-EDDY SIMULATION ; SOLAR-RADIATION ; CLOUD RADAR ; STRATOCUMULUS CLOUDS ; ABSORPTION ; MODELS ; TEMPERATURE ; RETRIEVAL ; REFLECTIVITY ; CEILOMETERS |
WOS类目 | Environmental Sciences ; Meteorology & Atmospheric Sciences |
WOS研究方向 | Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/30924 |
专题 | 地球科学 |
作者单位 | 1.Univ Paris Saclay, Ecole Polytech, Lab Meteorol Dynam, F-91128 Palaiseau, France; 2.Univ Paris Saclay, Ecole Polytech, CNRS, Inst Pierre Simon Laplace, F-91128 Palaiseau, France; 3.Univ Paris Saclay, Ecole Polytech, UVSQ, Inst Pierre Simon Laplace, F-91128 Palaiseau, France; 4.UPMC, CNRS, UVSQ, Lab Atmospheres,Milieux,Observat Spatiales, F-78280 Guyancourt, France; 5.Univ Lille, UMR CNRS 8518, Lab Opt Atmospher, F-59000 Lille, France |
推荐引用方式 GB/T 7714 | Waersted, Eivind G.,Haeffelin, Martial,Dupont, Jean-Charles,et al. Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing[J]. ATMOSPHERIC CHEMISTRY AND PHYSICS,2017,17(17). |
APA | Waersted, Eivind G.,Haeffelin, Martial,Dupont, Jean-Charles,Delanoe, Julien,&Dubuisson, Philippe.(2017).Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing.ATMOSPHERIC CHEMISTRY AND PHYSICS,17(17). |
MLA | Waersted, Eivind G.,et al."Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing".ATMOSPHERIC CHEMISTRY AND PHYSICS 17.17(2017). |
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