In this study, we measured the droplet size distribution(DSD) and visibility of sea fog using a fog droplet spectrometer and visibility meter, respectively, during the July 23-August 3 and August 22-September 13 perio...In this study, we measured the droplet size distribution(DSD) and visibility of sea fog using a fog droplet spectrometer and visibility meter, respectively, during the July 23-August 3 and August 22-September 13 periods of the 2016 Chinese National Arctic Research Expedition. We calculated the visibility using the Mie theory and the DSD data and then compared the calculated with the observed visibility. The comparison shows that the deviations in the calculated visibility caused by DSD data sampling errors cannot be ignored. During navigation, wind and ship speeds tended to push or pull the sampled air and cause turbulence pulsation, which influenced the sampling of the fog droplet spectrometer. This influence is weak when the liquid water content(LWC) is high but becomes stronger as the LWC decreases. Taking the sailing speed and heading into consideration, the wind speed component parallel and perpendicular to the air inlet of the fog droplet spectrometer exhibit different laws in the deviation. By performing a fitting analysis of the calculated and observed visibilities under different wind speeds and wind directions, here, we present two sets of correction coefficients for the two wind-speed components and a method for correcting the calculated visibility. This correction method shows excellent results.展开更多
In fog, visibility is reduced. This reduction in visibility is measured by the meteorological optical range (MOR), which is important for studying human perception and various sensors in foggy conditions. The Cerema P...In fog, visibility is reduced. This reduction in visibility is measured by the meteorological optical range (MOR), which is important for studying human perception and various sensors in foggy conditions. The Cerema PAVIN Fog & Rain platform is capable of producing calibrated fog in order to better analyses it and understand its consequences. The problem is that the droplets produced by the platform are not large enough to resemble real fog. This can have a major impact on measurements since the interaction between electromagnetic waves and fog depends on the wavelength and diameter of the droplets. To remedy this, Cerema is building a new platform with new equipment capable of generating fog. This study analyses different nozzles and associated usage parameters such as the type of water used and the pressure used. The aim is to select the best nozzle with the associated parameters for producing large-diameter droplets and therefore more realistic fog.展开更多
Microphysical properties of sea fog and correlations of these properties were analyzed based on the measurements from a comprehensive field campaign carried out from 15 March to 18 April 2010 on Donghai Island （21...Microphysical properties of sea fog and correlations of these properties were analyzed based on the measurements from a comprehensive field campaign carried out from 15 March to 18 April 2010 on Donghai Island （21°35″N, 110°32″5′E） in Zhanjiang, Guangdong Province, China. There were four types of circula- tion pattern in favor of sea fog events in this area identified, and the synoptic weather pattern was found to influence the microphysical properties of the sea fogs. Those influenced by a warm sector in front of a cold front or the anterior part of low pressure were found to usually have a much longer duration, lower visibility, greater liquid water content, and bigger fog droplet sizes. A fog droplet number concentration of N≥1 cm-a and liquid water content of L≥0.001 g m-a can be used to define sea fogs in this area. The type of fog droplet size distribution of the sea fog events was mostly monotonically-decreasing, with the spectrum width always being 〉20 μm. The significant temporal variation of N was due in large part to the number concentration variation of fog droplets with radius 〈3 μm. A strong collection process appeared when droplet spectrum width was 〉10 μm, which subsequently led to the sudden increase of droplet spectrmn width. The doln- inant physical process during the sea fog events was activation with subsequent condensational growth or reversible evaporation processes, but turbulent mixing also played an important role. The collection process occurred, but was not vital.展开更多
针对一种先进的新型喷药机具DYNA-FOGR MAX I-PROTM 2P 2743型超低量喷雾机,应用雾滴谱显微镜测定方法在实验室测量了该喷雾机的雾滴粒谱及喷雾量与粒谱的关系。试验表明该机喷射雾滴直径NMD为25μm,VMD为50μm,适用合于大型仓库、车站...针对一种先进的新型喷药机具DYNA-FOGR MAX I-PROTM 2P 2743型超低量喷雾机,应用雾滴谱显微镜测定方法在实验室测量了该喷雾机的雾滴粒谱及喷雾量与粒谱的关系。试验表明该机喷射雾滴直径NMD为25μm,VMD为50μm,适用合于大型仓库、车站、码头、垃圾场等大面积区域的灭虫、灭菌防治作业。展开更多
基金supported by the National Natural Science Foundation of China (No. 41330960)the National Major Science Project of China for Global Change Research (No. 2015CB953900)the Major State Basic Research Development Program (No. 2016YFC1402702)
文摘In this study, we measured the droplet size distribution(DSD) and visibility of sea fog using a fog droplet spectrometer and visibility meter, respectively, during the July 23-August 3 and August 22-September 13 periods of the 2016 Chinese National Arctic Research Expedition. We calculated the visibility using the Mie theory and the DSD data and then compared the calculated with the observed visibility. The comparison shows that the deviations in the calculated visibility caused by DSD data sampling errors cannot be ignored. During navigation, wind and ship speeds tended to push or pull the sampled air and cause turbulence pulsation, which influenced the sampling of the fog droplet spectrometer. This influence is weak when the liquid water content(LWC) is high but becomes stronger as the LWC decreases. Taking the sailing speed and heading into consideration, the wind speed component parallel and perpendicular to the air inlet of the fog droplet spectrometer exhibit different laws in the deviation. By performing a fitting analysis of the calculated and observed visibilities under different wind speeds and wind directions, here, we present two sets of correction coefficients for the two wind-speed components and a method for correcting the calculated visibility. This correction method shows excellent results.
文摘In fog, visibility is reduced. This reduction in visibility is measured by the meteorological optical range (MOR), which is important for studying human perception and various sensors in foggy conditions. The Cerema PAVIN Fog & Rain platform is capable of producing calibrated fog in order to better analyses it and understand its consequences. The problem is that the droplets produced by the platform are not large enough to resemble real fog. This can have a major impact on measurements since the interaction between electromagnetic waves and fog depends on the wavelength and diameter of the droplets. To remedy this, Cerema is building a new platform with new equipment capable of generating fog. This study analyses different nozzles and associated usage parameters such as the type of water used and the pressure used. The aim is to select the best nozzle with the associated parameters for producing large-diameter droplets and therefore more realistic fog.
基金mainly provided by the Meteorology Fund of the Ministry of Science and Technology (Grant No. GYHY[QX] 2007-6-26)the National Natural Science Foundation of China (Grant No. 41275151)+1 种基金the Qing-Lan Project for Cloud-Fog-Precipitation-Aerosol Study in Jiangsu Province, the Graduate Student Innovation Plan for the Universities of Jiangsu Province (Grant No. CX10B 292Z)a project funded by the Priority Academic Development of Jiangsu Higher Education Institutions
文摘Microphysical properties of sea fog and correlations of these properties were analyzed based on the measurements from a comprehensive field campaign carried out from 15 March to 18 April 2010 on Donghai Island （21°35″N, 110°32″5′E） in Zhanjiang, Guangdong Province, China. There were four types of circula- tion pattern in favor of sea fog events in this area identified, and the synoptic weather pattern was found to influence the microphysical properties of the sea fogs. Those influenced by a warm sector in front of a cold front or the anterior part of low pressure were found to usually have a much longer duration, lower visibility, greater liquid water content, and bigger fog droplet sizes. A fog droplet number concentration of N≥1 cm-a and liquid water content of L≥0.001 g m-a can be used to define sea fogs in this area. The type of fog droplet size distribution of the sea fog events was mostly monotonically-decreasing, with the spectrum width always being 〉20 μm. The significant temporal variation of N was due in large part to the number concentration variation of fog droplets with radius 〈3 μm. A strong collection process appeared when droplet spectrum width was 〉10 μm, which subsequently led to the sudden increase of droplet spectrmn width. The doln- inant physical process during the sea fog events was activation with subsequent condensational growth or reversible evaporation processes, but turbulent mixing also played an important role. The collection process occurred, but was not vital.
文摘针对一种先进的新型喷药机具DYNA-FOGR MAX I-PROTM 2P 2743型超低量喷雾机,应用雾滴谱显微镜测定方法在实验室测量了该喷雾机的雾滴粒谱及喷雾量与粒谱的关系。试验表明该机喷射雾滴直径NMD为25μm,VMD为50μm,适用合于大型仓库、车站、码头、垃圾场等大面积区域的灭虫、灭菌防治作业。
