关键词: 辐射雾, 气象要素, 空气污染物

Abstract:

Based on the surface and upper air meteorological data and air quality data in the Beijing-Tianjin-Hebei region, the climatic characteristics of radiation fog and the variations of influence factors and particle pollutants of various scales before and after the occurrence of radiation fog from 2000 to 2020 were analyzed.The results show that the radiation fog occurs frequently in the central and southern plains of the Beijing-Tianjin-Hebei region, whereas such a fog rarely occurs in the Bashang plateau and the mountainous area in the northwest of Beijing.The minimum visibility of radiation fog generally decreases to 0.1~0.6 km and increases significantly with the sunrise.The high-low temperature differences, i.e.the differences between the maximum temperature on the day before the occurrence of radiation fog and the minimum temperature of the radiation fog day are concentrated between 6.0 ℃ and 10.4 ℃, with the maximum up to 20.3 ℃, and the minimum is 0 ℃ and the value varies significantly in different regions.The high-low temperature differences in spring appear larger than those in other seasons, but the maximum and minimum differences appear in winter.At 14:00 on the day before the occurrence of radiation fog, the surface wind speed is mostly varying from 1.0~2.4 m·s^-1, whereas at 20:00 and 08:00 on the fog day, the wind speed decreases to around 1.0 m·s^-1, with the wind direction of north and south.Vertical inverses tend to start at ground level and usually appear shallow, with wind direction shifting counterclockwise from north to west with height.On the day when the fog breaks out, the temperature and wind speed increase whereas the humidity decreases with sunrise, and PM_2.5 and PM₁₀ level decrease, resulting in the air pollution level gradually decreasing.

Key words: Radiation fog, Meteorological elements, Air pollutants