Positive and negative influences of landfalling typhoons on tropospheric ozone over southern China

In this study, we use an ensemble of 17 landfalling typhoons over 2014–2018 to investigate the positive and negative influences of typhoons on tropospheric ozone over southern China. Referring to the proximity to typhoons and typhoon developmental stages, we found that surface ozone is enhanced when typhoons are 400–1500 km away during the initial stages of typhoons (e.g., from 1 day before and to 1 day after typhoon genesis). The positive ozone anomaly averagely reaches 10–20 ppbv at the daytime and 9 ppbv at nighttime compared with the background ozone level. Particularly, surface ozone at radial distances of 1100–1300 km is most significantly enhanced during these initial stages. As the typhoons approach and land in southern China, the influences of typhoons change from enhancing to reducing ozone. Surface ozone concentrations decrease with a negative ozone anomaly ranging between -12 % ~ -17 % relative to the background ozone level. We explore the physical linkages between typhoons, meteorological conditions and ozone variations. Results show that during typhoon initial stages, the increasing temperature and weak winds in the atmospheric boundary layer (ABL) and dominating downward motions promote ozone production and accumulation over the outskirts of typhoons. While the deteriorating weather accompanied by dropping temperature, wind gales and convective activity reduces the production and accumulation of surface ozone when typhoons are making landfalling. Variations of tropospheric ozone profiles during the differential developmental stages of landfalling typhoons are further examined to quantify the influences of typhoon-induced stratospheric intrusions on lower troposphere and surface ozone. Using temporally dense ozone vertical observations, we found two regions of high ozone concentrations separately located in the ABL and the middle-to-upper troposphere under the influences of typhoons. Averagely, the ozone enhancement maximizes around 10–12 ppbv at 1–1.5 km altitude at the typhoon initial stages. The ozone enhancement persists over a longer period in the middle-to-upper troposphere with a positive ozone anomaly of 10 ppbv at 7–8 km altitude shortly after typhoon genesis, and 30 ppbv near 12 km altitude when typhoons reach their maximum intensity. When typhoons are landing, a negative ozone anomaly appears and extends upward with a maximum ozone reduction of 14–18 ppbv at 5 km altitude and 20–25 ppbv at 11 km altitude. Though the overall tropospheric ozone is usually reduced during typhoon landfalling, we quantify that five of eight typhoon samples deduce ozone-rich air with the stratospheric origin (80 ppbv) above 4 km altitude, and in 3 typhoon cases the ozone-rich air intrusions (60 ppbv) can sink to the ABL. This suggests that the typhoon-induced stratospheric ozone-rich air intrusions play an important role in surface ozone enhancement.

Applications of ozone therapy in urology [abstract]

BACKGROUND: Ozone therapy has been successfully used in various diseases for years. But, what about urological diseases? We used ozone therapy for the treatment of several urological diseases. MATERIAL and METHODS: From November 2016 up to now, we performed ozone therapy to treat intractable urethritis in 16 patients, chronic prostatitis/chronic pelvic pain syndrome in 14 patients, chronic cystitis in 14 patients, erectile dysfunction in 21 patients. We used several criteria to test the effectiveness of the ozone therapy. RESULTS: According to the follow-up results, we obtained complete success in more than 90% of the patients, complains of almost 5% the patients relieved to tolerable degree. The remaining 5% was unresponsive to the ozone therapy. We did not experience of any complications. DISCUSSION: Our results showed that ozone can be used to treat intractable and challenging urological diseases without any complications. Determining the right patient to be treated with ozone safely, ozone application route and ozone dose are the most essential steps. Therefore, selection criteria of treatable patients must be clarified with increasing clinical experience soon. CONCLUSION: This study summarizes and showed that different modalities of ozone therapy applications in various intractable or chronic urological diseases can be used successfully and safely.

Contribution of horizontal and vertical advection to the formation of small-scale vertical structures of ozone in the lower and middle stratosphere at Fairbanks, Alaska

The contribution of vertical and horizontal advection to the production of small-scale vertical ozone structures was investigated using data from an ozonesonde observation performed at intervals of 3 h in Fairbanks (64.8N, 147.9W), Alaska. The dominant vertical scales of the ozone mixing ratio were determined to be 2–5 km, which were similar to those of horizontal winds and the temperature of the lower and middle stratosphere, using spectral analysis. Ozone fluctuations due to vertical advection were estimated from the potential temperature fluctuation and vertical gradient of the background ozone mixing ratio. Residual ozone fluctuations are attributed to horizontal advection. Fluctuations due to horizontal advection are dominant, as reported in previous studies. The cross-correlation of the effects of vertical and horizontal advection was also evaluated. The correlation is relatively larger at altitudes of 18–23 km and 32–33 km compared to those at other height regions. In contrast to previous studies, horizontal advection by gravity waves seems to play a dominant role in the production of small-scale ozone structures at altitudes of 32–35 km.

Exploring 2016–2017 surface ozone pollution over China: source contributions and meteorological influences

Severe surface ozone pollution over major Chinese cities has become an emerging air quality concern, raising a new challenge for emission control measures in China. In this study, we explore the source contributions to surface daily maximum 8 h average (MDA8) ozone over China in 2016 and 2017, the 2 years with the highest surface ozone averaged over Chinese cities in record. We estimate the contributions of anthropogenic, background, and individual natural sources to surface ozone over China using the GEOS-Chem chemical transport model at 0.25∘×0.3125∘ horizontal resolution with the most up-to-date Chinese anthropogenic emission inventory. Model results are evaluated with concurrent surface ozone measurements at 169 cities over China and show generally good agreement. We find that background ozone (defined as ozone that would be present in the absence of all Chinese anthropogenic emissions) accounts for 90 % (49.4 ppbv) of the national March–April mean surface MDA8 ozone over China and 80 % (44.5 ppbv) for May–August. It includes large contributions from natural sources (80 % in March–April and 72 % in May–August). Among them, biogenic volatile organic compound (BVOC) emissions enhance MDA8 ozone by more than 15 ppbv in eastern China during July–August, while lightning NOx emissions and ozone transport from the stratosphere both lead to ozone enhancements of over 20 ppbv in western China during March–April. Over major Chinese city clusters, domestic anthropogenic sources account for about 30 % of the May–August mean surface MDA8 ozone and reach 39–73 ppbv (38 %–69 %) for days with simulated MDA8 ozone > 100 ppbv in the North China Plain, Fenwei Plain, Yangtze River Delta, and Pearl River Delta city clusters. These high ozone episodes are usually associated with high temperatures, which induce large BVOC emissions and enhance ozone chemical production. Our results indicate that there would be no days with MDA8 ozone > 80 ppbv in these major Chinese cities in the absence of domestic anthropogenic emissions. We find that the 2017 ozone increases relative to 2016 are largely due to higher background ozone driven by hotter and drier weather conditions, while changes in domestic anthropogenic emissions alone would have led to ozone decreases in 2017. Meteorological conditions in 2017 favor natural source contributions (particularly soil NOx and BVOC ozone enhancements) and ozone chemical production, increase the thermal decomposition of peroxyacetyl nitrate (PAN), and further decrease ozone dry deposition velocity. More stringent emission control measures are thus required to offset the adverse effects of unfavorable meteorology, such as high temperature, on surface ozone air quality.

Exploring 2016–2017 surface ozone pollution over China: source contributions and meteorological influences

Severe surface ozone pollution over major Chinese cities has become an emerging air quality concern, raising a new challenge for emission control measures in China. In this study, we explore the source contributions to surface daily maximum 8-h average (MDA8) ozone over China in 2016 and 2017, the two years with the highest surface ozone averaged over Chinese cities in record. We estimate the contributions of anthropogenic, background, and individual natural sources to surface ozone over China, using the GEOS-Chem chemical transport model at 0.25° × 0.3125° horizontal resolution with the most up-to-date Chinese anthropogenic emission inventory. Model results are evaluated with concurrent surface ozone measurements at 169 cities over China and show general good agreement. We find that background ozone (defined as ozone that would be presented in the absence of all Chinese anthropogenic emissions) accounts for 90 % (49.4 ppbv) of the national March–April mean surface MDA8 ozone over China and 80 % (44.5 ppbv) for May–August. It includes large contributions from natural sources (80 % in March–April and 72 % in May–August). Among them, biogenic volatile organic compounds (BVOCs) emissions enhance MDA8 ozone by more than 15 ppbv in eastern China during July–August, while lightning NOx emissions and ozone transport from the stratosphere both lead to ozone enhancements of over 20 ppbv in western China during March–April. Over major Chinese city clusters, domestic anthropogenic sources account for about 30 % of the May–August mean surface MDA8 ozone, and reach 39–73 ppbv (38 %–69 %) for days with simulated MDA8 ozone > 100 ppbv in the Northern China Plain, Fenwei Plain, Yangtze River Delta, and Pearl River Delta city clusters. These high ozone episodes are usually associated with high temperatures, which induce large BVOCs emissions and enhance ozone chemical production. Our results indicate that there would be no days with MDA8 ozone > 80 ppbv in these major Chinese cities in the absence of domestic anthropogenic emissions. We find that the 2017 ozone increases relative to 2016 are largely due to higher background ozone driven by hotter and dryer weather conditions, while changes in domestic anthropogenic emissions alone would have led to ozone decreases in 2017. Meteorological conditions in 2017 favor natural source contributions (particularly soil NOx and BVOCs ozone enhancements) and ozone chemical production, increase thermal decomposition of peroxyacetyl nitrate (PAN), and further decrease ozone dry deposition velocity. More stringent emission control measures are thus required to offset the adverse effects of unfavorable meteorology such as high temperature on surface ozone air quality.