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YUE Yanyu, NIU Shengjie, ZHAO Lijuan, ZHANG Yu, XU Feng. 2013: Study on the Synoptic System and Macro-Micro Characteristicsof Sea Fog along the Zhanjiang Coastal Area. Chinese Journal of Atmospheric Sciences, 37(3): 609-622. DOI: 10.3878/j.issn.1006-9895.2012.12009
Citation: YUE Yanyu, NIU Shengjie, ZHAO Lijuan, ZHANG Yu, XU Feng. 2013: Study on the Synoptic System and Macro-Micro Characteristicsof Sea Fog along the Zhanjiang Coastal Area. Chinese Journal of Atmospheric Sciences, 37(3): 609-622. DOI: 10.3878/j.issn.1006-9895.2012.12009

Study on the Synoptic System and Macro-Micro Characteristicsof Sea Fog along the Zhanjiang Coastal Area

  • Based on data of droplet spectra, visibility, temperature field, wind field, and meteorological elements for twelve cases from a comprehensive fog experiment carried out at the radar station on Donghai Island of Guangdong from February to March 2011, we classified the weather synoptic system for fog occurrence and analyzed the meteorological elements, boudary layer structures, and microphysical properties. Furthermore, a typical case was studied. It is summarized that when Zhanjiang is located at forepart of depression, cold front and rearward of high pressure, the frequency of fog occurrence was high. During the fog events, the wind direction was mainly easterly near the surface, and southerly and easterly in the upper air. The range of fog droplets number concentration (N), liquid water content (LWC), and average radius was 170-372 cm-3, 0.018-0.170 g m-3, and 1.71-3.28 μm, respectively. The initial stage of the development of Case 11 was dominated by droplet activation and condensational growth. N increased with a slight variation of radius when the water vapor was not sufficient for the growth of fog condensation nuclei. In the mature stage, according to the auto conversion threshold functions, the collision-coalescence efficiency and the number density of large droplets increased, and the drop-size distribution expanded. Combined with the meteorological elements in the boundary layer, we demonstrated that the wind jets were significant at night, inhibiting the growth of the fog droplets, and the LWC was low. The reasons for the sharp increase in average radius might be the strong inversion of the virtual temperature and the low wind speed. Statistical analysis showed that the droplets spectrum had a bimodal distribution and could be described by the Gamma distribution.The relationships between LWC and the extinction coefficient and the effective radius were positive with a correlation coefficient 0.95 and 0.97, respectively.
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