Tropospheric ozone pollution poses a major environmental challenge in China. As its primary natural source, Stratosphere-to-Troposphere Transport (STT) has been recognized as a significant contributor to tropospheric ozone in western, northeastern, and eastern China. However, the extent of STT’s influence on southeastern China has been less studied due to data limitations. Using a recently available one-year dataset of ozonesonde observations from a regional background station, we find that STT contributes significantly to tropospheric and surface ozone elevation in southeastern China. Our results show that STT plays a more substantial role in shaping tropospheric ozone during spring than previously believed, accounting for over 30% of ozone concentrations above 4 km. Without the stratospheric contribution, the spring seasonal peak almost disappears. STT can also significantly influence ozone concentrations at the surface. For example, a distinct ozone profile was observed on 4 May 2022, with a notable increase in tropospheric ozone. This tropospheric ozone increase was caused by a STT event triggered by a robust horizontal trough and subsequent southward movement of subtropical jets in the upper troposphere. According to a stratospheric tracer derived from an atmospheric chemistry model, this STT event contributed to 25%–30% of the surface ozone increase. Overall, this study highlights the important role of STT in driving tropospheric ozone variations, even in regions with comparatively lower ozone levels in southeastern China.

The northward typhoon configuration along the southeast coast of China (TCN-SEC) is one of the key circulation patterns influencing the coastal cities in southeast China (CCSE). Here, we analyzed the air quality in CCSE during the high-incidence typhoon period from 2019 to 2021. Multi-source measurements were carried out to explore the impact of super typhoon 2114 ‘Chanthu’ on the air quality in CCSE. The results showed that the TCN-SEC and its surrounding weather situation had a favorable impact on the increase in pollutant concentration in CCSE, especially on the increase in O3 concentration. From 13 September to 17 September 2021, affected by the cyclonic shear in the south of super typhoon 2114 ‘Chanthu,’ the strong wind near the ground, stable relative humidity, strong precipitation, and the significantly reduced wind speed had a substantial effect on PM10, PM2.5, SO2, and NO2 concentrations. Calm and light air near the ground, weak precipitation, high daily maximum temperatures, and minimum relative humidity may provide favorable meteorological conditions for the accumulation of O3 precursors and photochemical reactions during the day, resulting in the daily peak values of O3 exceeding 160 μg/m3. The evolution of wind, relative humidity, and boundary layer height could play an important role in the variations in PM10 and PM2.5 concentrations by influencing pollutant accumulation or diffusion. It was suggested that the atmospheric structure of horizontal stability and vertical mixing below 1500 m could play a significant role in the accumulation and vertical distribution of ozone. The results highlight the important role of typhoons in the regional environment and provide a scientific basis for further application of multi-source observation data, as well as air pollution control.

An understanding of the vertical distribution of ozone is critical to assessing the ozone variabilities both in the stratosphere and the troposphere. We collected the profiles of atmospheric ozone partial pressure and ozone volume mixing ratio (VMR) by a sounding system at the Wuyi Mountain National Meteorological Observation Station (Shaowu sounding station 58725) from November 2021 to February 2022. In this study, the vertical distribution and sub-peak phenomenon of tropospheric ozone below 12 km are investigated using mathematical statistics and synthetic analysis. The results show that the ozone partial pressure decreased from the ground to the tropopause, which is consistent with the temperature profile. However, 66.7% of cases first showed an increasing trend from the ground to about 3 km, while there were one or more temperature inversions in the corresponding temperature profiles and the atmosphere was stable and the relative humidity was high; then, in the stratosphere, the ozone partial pressure began to increase significantly, The ozone partial pressure reaches its maximum at an average height of 24.9 km, and the maximum value was 14 mPa. The ozone VMR in troposphere is the fluctuating increase from the ground to the tropopause, and 83.3% of the cases begin to rise rapidly at about 2–5 km away from the tropopause, and the ozone surge height is 2.9 km lower than the tropopause on average. Some of these tropopause ozone VMR have shown the characteristics of stratospheric ozone. The sub-peaks of tropospheric ozone below 12 km has four cases. All the sub-peaks occur between 6.7 km and 11.5 km vertically, and peak ozone VMR is 1.6–1.9 times larger than that of the average state at the same height. The maximum stratospheric ozone VMR is 8649 ppb on average, occurring at an average height of 31.3 km, and this average height of the maximum stratospheric ozone VMR is 6.4 km higher than that for the ozone partial pressure. The total ozone in the boundary layer (0–1.5 km) is 4.3 DU on average, accounting for 1.5% in total ozone column. The total ozone in the troposphere is 39.5 DU, accounting for 13.1% in total ozone column, and the total ozone in the stratosphere is 262.4 DU, accounting for 86.9% in total ozone column.

Understanding the vertical structure of ozone concentrations in different seasons and their correlations with the associated meteorological conditions is crucial for exploring atmospheric ozone variability and improving the accuracy of regional ozone prediction. In this study, an ozone-sounding experiment was carried out at the Shaowu sounding Station in Fujian from November 2021 to May 2022 in order to obtain vertical profiles of ozone concentrations and synoptic variables. Based on these observations, we examined the characteristics of tropospheric ozone profiles in spring over the Wuyishan region and their comparison with wintertime ozone. The results show that compared with winter, the total ozone column (TOC) in spring has increased by 64.4%, with an enhancement of 23.8% for the troposphere and a greater increment of 69.1% for the stratosphere. The sub-peaks of tropospheric ozone below 12 km are found in both spring and winter of 2022, which are accompanied by lower relative humidity (<10% in winter and <15% in spring), temperature inversions in some cases, and intensive westerly winds. Furthermore, we investigated the relationship between ozone volume mixing ratio (OVMR) and synoptic conditions in the Wuyishan region and concluded that OVMR above 1.5 km is negatively correlated with temperature and relative humidity but positively correlated with wind speed. Additionally, springtime OVMR in the middle and upper troposphere exhibits a "funnel" distribution, showing a higher OVMR on the day of sounding observations and one day before and after that on adjacent days with low-level southwesterly winds and updrafts. While in winter, the strong downdrafts dominate on the sounding observation day.

Based on the visibility,relative humidity,precipitation,synoptic situations and the concentration of PM10 from 2006 to 2010 in Fujian province,the characteristics of lowvisibility weather and its impacting factors were analyzed,and the coastal cities were divided into three city groups,i. e. the north,the middle and the south. The results indicate that the annual haze days are from 8 to 26 days in the north city group and the lowvisibility is caused by( light) fog,while it is caused by haze in other two city groups. The( light) fog and haze weather usually occur in December to June and seldom in other months. The mean visibility is higher in summer and autumn than in winter and spring. The short duration for the lowvisibility weather,light fog and haze is prevailing,and then is half a day; the least is the whole day in three city groups. The light fog usually occurs under lowvortex shear condition,and then under upper trough and warm zone convergence condition,the third is under transformed surface cold high condition,while haze is often under warm zone convergence,upper trough and transformed surface cold high conditions. The mass concentrations of PM10 are 0. 068-0. 109 mg·m- 3,0. 044-0. 064 mg·m- 3 and 0. 041-0. 072 mg·m-3 under haze,( light) fog and non-lowvisibility weather conditions.

福州为福建省霾天气高发区之一.文章利用2006-2010年历史探空数据以及福州站地面观测资料中常规数据,结合天气形势,开展基于V-3θ方法的福州霾低能见度天气预报研究,研究结果表明:当福州处于暖区辐合内部时霾发生率最高,其次是变性冷高压和高空槽,而低涡切变及台风和热带辐合带则不易出现霾;V-3θ结构图上判断霾天气发生的主要要素为厚度超过25 hPa的逆温层及其上下的滚流特征、中低层非均匀结构以及暖层云;预判霾天气消散的大气结构特征主要为风场的变化,分别为整层顺滚流结构和整层逆滚流结构;根据上述要素的特征及变化趋势对2011年针对福州市霾天气进行预报检验,取得一定的预报效果,霾日的预报准确率达77％.

Based on the routine meteorologic data and air sounding data from 2003 to 2007 in Northwest Fujian,the characteristics of the leading weather systems influencing on local precipitation were analyzed.The result shows that,low-vortex shear is the chief precipitation weather system in Northwest Fujian,and then are continental-high base and warm sector convergence.There are visible differences in the precipitation distribution of each grade for the 10 kinds of weather systems.The opportunity of storm rain is largest when the weather is controlled by low-pressure inverted trough.Northwest Fujian is affected most by the southern part of low-vortex shear,of which the southern,middle and northern parts are the positions relatively suitable for local artificial precipitation operation.The occurrence rate of storm rain is great when the weather is controlled by low-vortex shear in spring,so it should be circumspect when carrying out artificial precipitation operation.The height of 0℃ layer is below 4200 meter on average,and the monthly distribution changes as unimodal shape,for which January is the lowest while July the highest.