Near-ground Ozone Research Articles

A Deep Forest Algorithm Based on TropOMI Satellite Data to Estimate Near-Ground Ozone Concentration

A Deep Forest Algorithm Based on TropOMI Satellite Data to Estimate Near-Ground Ozone Concentration

Evaluating WRF-GC v2.0 predictions of boundary layer height and vertical ozone profile during the 2021 TRACER-AQ campaign in Houston, Texas

Abstract. The TRacking Aerosol Convection ExpeRiment – Air Quality (TRACER-AQ) campaign probed Houston air quality with a comprehensive suite of ground-based and airborne remote sensing measurements during the intensive operating period in September 2021. Two post-frontal high-ozone episodes (6–11 and 23–26 September) were recorded during the aforementioned period. In this study, we evaluated the simulation of the planetary boundary layer (PBL) height and the vertical ozone profile by a high-resolution (1.33 km) 3-D photochemical model, the Weather Research and Forecasting (WRF)-driven GEOS-Chem (WRF-GC). We evaluated the PBL heights with a ceilometer at the coastal site La Porte and the airborne High Spectral Resolution Lidar 2 (HSRL-2) flying over urban Houston and adjacent waters. Compared with the ceilometer at La Porte, the model captures the diurnal variations in the PBL heights with a very strong temporal correlation (R>0.7) and ±20 % biases. Compared with the airborne HSRL-2, the model exhibits a moderate to strong spatial correlation (R=0.26–0.68), with ±20 % biases during the noon and afternoon hours during ozone episodes. For land–water differences in PBL heights, the water has shallower PBL heights compared to land. The model predicts larger land–water differences than the observations because the model consistently underestimates the PBL heights over land compared to water. We evaluated vertical ozone distributions by comparing the model against vertical measurements from the TROPospheric OZone lidar (TROPOZ), the HSRL-2, and ozonesondes, as well as surface measurements at La Porte from a model 49i ozone analyzer and one Continuous Ambient Monitoring Station (CAMS). The model underestimates free-tropospheric ozone (2–3 km aloft) by 9 %–22 % but overestimates near-ground ozone (<50 m aloft) by 6 %-39 % during the two ozone episodes. Boundary layer ozone (0.5–1 km aloft) is underestimated by 1 %–11 % during 8–11 September but overestimated by 0 %–7 % during 23–26 September. Based on these evaluations, we identified two model limitations, namely the single-layer PBL representation and the free-tropospheric ozone underestimation. These limitations have implications for the predictivity of ozone's vertical mixing and distribution in other models.

Transmission paths and source areas of near-surface ozone pollution in the Yangtze River delta region, China from 2015 to 2021

Near-ground ozone in the Yangtze River Delta (YRD) region has become one of the main air pollutants that threaten the health of residents. However, to date, the transport behavior and source areas of ozone in the YRD region have not been systematically analyzed. In this study, by combining the ozone observational record with a HYSPLIT (hybrid single-particle Lagrangian integrated trajectory) model, we tried to reveal the spatiotemporal regularity of the airflow transport trajectory of ozone. Spatially, high ozone concentrations mainly clustered in industrial cities and resource-based cities. Temporally, the center of the ozone pollution shifted westward of Nanjing from 2015 to 2021. With the passage of time, the influence of meteorological elements on the ozone concentration in the YRD region gradually weakened. Marine atmosphere had the most significant impact on the transmission path of ozone in Shanghai, of which the trajectory frequency in 2021 accounted for 64.21% of the total frequency. The transmission trajectory of ozone in summer was different from that in other seasons, and its transmission trajectory was mainly composed of four medium-distance transmission paths: North China-Bohai Sea, East China Sea-West Pacific Ocean, Philippine Sea, and South China Sea-South China. The contribution source areas mainly shifted to the southeast, and the emission of pollutants from the Shandong Peninsula, the Korean Peninsula-Japan, and the Philippine Sea-Taiwan area increased the impact of ozone pollution in the Shanghai area from 2019 to 2021. This study identified the regional transport path of ozone in the YRD region and provided a scientific reference for the joint prevention and control of ozone pollution in this area.

Estimation of Near-Ground Ozone With High Spatio-Temporal Resolution in the Yangtze River Delta Region of China Based on a Temporally Ensemble Model

Estimation of Near-Ground Ozone With High Spatio-Temporal Resolution in the Yangtze River Delta Region of China Based on a Temporally Ensemble Model

Analysis of Ozone Pollution Characteristics and Transport Paths in Xi’an City

Xi’an is a key city for air-pollution prevention and control in China, and its near-ground ozone (O3) pollution has become a key issue whose resolution is urgent. The spatial and temporal variations in ozone pollution and their relationship with meteorological factors, transport pathways, and potential source distribution in Xi’an City were investigated in this study using the backward trajectory clustering analysis, potential source contribution function (PSCF), and concentration weight trajectory (CWT) methods coupled with the hourly ozone-mass concentration observations and meteorological data from 2014 to 2020. The results indicate that Xi’an City has suffered from increasingly severe ozone pollution in recent years. Overall, the annual average mass concentration of O3_8h_max presented an upward trend, exhibiting a 34.94% increase from 2014 to 2020. A seasonal variation peak occurred in summer, and the monthly variations featured an inverted “V” shape. Furthermore, the diurnal variation was significantly affected by the near-surface atmospheric photochemical process, showing a discernible single-peak and single-valley distribution with a peak between 15:00 and 17:00. The O3 concentration demonstrated a significant linear positive correlation with surface temperature and sunshine duration. When the relative humidity was 30~50%, the temperature was above 30 °C, and the wind speed was ≤4 m/s, high-concentration O3 pollution was liable to occur. The transmission mainly relied on short-distance airflow during periods of heavy O3-polluted weather. In this context, in addition to local O3 generation, high O3 concentrations were also affected by the large NOx and VOC emissions from heavy industries in neighboring cities in Shaanxi Province, southwest Shanxi Province, and northern Henan Province. Therefore, joint prevention and control measures on the O3 pollution in Xi’an City must be adopted throughout the Fenwei Plain area with the aim of strictly controlling the emissions from regional pollution sources.

Insight into ozone profile climatology over northeast China from aircraft measurement and numerical simulation

Tropospheric ozone is a major pollutant that can harm human health, animals and plants. With a rapid development in Northeast China, ozone pollution has become an increasingly serious environmental challenge. To study the ozone distribution and the potential sources of ozone precursors in Northeast China, we analyzed vertical ozone profiles from the In-service Aircraft for a Global Observing System (IAGOS) in 2012–2014 and provided the climatological vertical structure of tropospheric ozone over Shenyang. The tropospheric ozone generally presents high in hot months, mainly due to the combined effects of the strong solar radiation and high volatile organic compounds emission in summer. While in cold months, the ozone is low because of weak solar radiation and high nitrogen oxides emission. Besides, a low-ozone center exists within lower troposphere in August, which is mainly caused by the East Asian summer monsoon prevailing in summer. To analyze the sources of ozone, typical ozone pollution episodes were studied and the results revealed the different pathways for the enhancement of ozone pollution in Shenyang: regional transport of anthropogenic emissions from North China Plain (NCP), long-range transport from Siberian biomass burning and local photochemical production. Modeling results show that the largest contribution to the surface ozone in Northeast China is local anthropogenic emissions (exceed 90%); the regional transport of NCP anthropogenic emissions contribute more to the pollutants around 2 km, and account for more than 50% pollutants during highly ozone polluted days; through long-range transport, Siberian biomass burning in the spring also have a nonnegligible effect on the near-ground ozone in Northeast China. Overall, this study provides tropospheric ozone climatology and its source attribution in Northeast China, and highlight the great importance of regional transport of anthropogenic and biomass burning emissions in ozone pollution.

Upgrade and automation of the JPL Table Mountain Facility tropospheric ozone lidar (TMTOL) for near-ground ozone profiling and satellite validation

Abstract. As part of international efforts to monitor air quality, several satellite missions such as the Tropospheric Monitoring Instrument (TROPOMI) were deployed and others, like Tropospheric Emissions: Monitoring Pollution (TEMPO), are planned for the near future. In support of the validation of these missions, major upgrades to the tropospheric ozone lidar located at the Jet Propulsion Laboratory Table Mountain Facility (TMF) were recently performed. These modifications include the full automation of the system, which now allows unattended measurements during frequent satellite overpasses, and a new receiver that extends the measurement capabilities of the system down to 100 m above surface. The automation led to the systematic operation of the lidar during daily TROPOMI overpasses, providing more than 139 reference profiles since January 2018. Ozone profiles retrieved using the new lidar receiver were compared to ozonesonde profiles obtained from a co-located tethered balloon. An agreement of about 5 % with the ozonesonde down to an altitude range of 100 m a.g.l. was observed. Furthermore, the stability of the receiver configuration was investigated. Comparisons between the lowest point retrieved by the lidar and a co-located surface ozone photometer showed no sign of drift over a 2-month test period and an agreement better than 10 %. Finally, measurements from a 24 h intensive measurement period during a stratospheric intrusion event showed good agreement with two free-flying ozonesondes. These comparisons revealed localized differences between sonde and lidar, possibly owing to the differing vertical resolutions (between 52 and 380 m for lidar and about 100 m for the sonde).

Long-Term Dynamics of Ozone in Surface Atmosphere at Remote Mountain, Rural and Urban Sites of South-East Siberia, Russia

Long-term monitoring of near-ground ozone concentration was performed in the remote mountain area as well as at rural and urban sites of South-East Siberia. Ozone concentrations at all three sites had similar seasonal dynamics with its maximum in spring and minimum in autumn. Such seasonal trends were characteristic of many areas of the Northern Hemisphere. Diurnal fluctuations of ozone concentrations were caused by photochemical generation of ozone at daytime and its partial depletion at night. Diurnal fluctuations were maximal in spring and summer and minimal in December and January in accordance with solar radiation intensity. At the urban site, mean ozone concentrations were significantly lower (about 2 times) than those in the rural and background areas. This was likely attributed to the increased consumption of ozone for oxidation of air pollutants in the urbanized area. A tendency to the decrease of mean annual ozone concentrations was recorded during long-term observations at the mountain site Mondy.

城区森林与乡村森林近地层臭氧浓度变化规律的对比研究

PDF HTML阅读 XML下载 导出引用 引用提醒 城区森林与乡村森林近地层臭氧浓度的变化规律对比 DOI: 10.5846/stxb201301150104 作者: 作者单位: 南京大学 生命科学学院,南京大学 生命科学学院,南京大学 生命科学学院,南京大学 生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31000226） Comparison of near-ground ozone concentrations between urban and rural forests Author: Affiliation: School of Life Science, Nanjing University,,,School of Life Science, Nanjing University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在基于城乡间环境梯度而发展的以“空间代替时间”研究陆地生态系统对全球气候变化响应的方法中，近地层臭氧的干扰是决定“城市自然大实验场”是否可行的最重要因素之一，但是城、乡近地层大气臭氧变化规律的研究却非常薄弱。以位于南京市中心的城区森林和镇江市下蜀的乡村森林为例，于2011年6月至2013年1月间，监测了近地层大气臭氧浓度，以及光照、温度、湿度等的变化动态，比较了两地臭氧浓度的日变化、季节变化规律。结果表明，城区样点与乡村样点相比，年平均气温高0.93℃，而相对湿度和光照强度最大值分别低3.37%和13108.77 lx。说明选择的样点有很好的代表性，反映了城、乡间典型的温湿度差异。而臭氧浓度的监测结果表明，乡村样点年平均臭氧浓度高于城区样点，但是生长季节（夏季）两样点间的差异不显著；城区和乡村样点一年中大于40 nL/L的时间分别是14%和13.9%；两样点AOT40的差异不显著。结果表明，虽然大部分时间乡村样点的近地层臭氧浓度高于城区样点，但是对研究陆地生态系统对全球气候变化响应的“城市自然大实验场”干扰较小。 Abstract:Numerous studies have shown that ecological factor changes along the spatial gradient of urban and rural sites have a strong similarity to the temporal gradient of global change. Therefore, based on environmental gradients between urban and rural areas, a space-for-time substitution experiment called the "urban nature experimental field" method is developed to research the response of the terrestrial ecosystem to global climatic change. In recent related studies, the characteristics of ecological factors in urban and rural areas were observed in many cities around the world, most of which were focused on temperature and carbon dioxide. However, some reports showed that the disturbance from near-ground ozone was one of the most influential factors in determining the effectiveness and applicability of the method. To date, little research has been carried out to monitor and identify the spatial variation of near-ground ozone concentrations along the urban-rural gradient. Therefore, we selected the following urban and rural forest sites: the urban site in Qingliangshan Park near the urban center of Nanjing, and the rural site in Xiashu at 41.7 km distance from the Nanjing city center. We monitored near-ground ozone concentrations, as well as light intensity, air temperature and humidity, from June 2011 to January 2013. We also compared diurnal and seasonal variation of ozone concentration. The results suggest that there were significant differences of temperature, humidity and maximum light intensity between the two observation sites (P < 0.001). Compared to the rural forest site, the urban site had an average 0.93℃ higher temperature, 3.37% lower humidity, and 13108.77 lx lower maximum light intensity. This shows typical differences of temperature and humidity between urban and rural sites, and implies the representativeness and appropriateness of the selection of the two monitoring sites. At the urban site, an annual average of 19.95 nL/L in near-gound ozone concentration was observed, slightly less than that at the rural site (23.24 nL/L). The difference pattern of ozone concentration between the two sites varied seasonally. In autumn, winter and spring, significantly higher seasonal average ozone concentrations were observed at the rural forest site, relative to the urban site (P < 0.01). In summer, there was no difference between the two sites (P > 0.05). Relative frequencies of ozone concentrations in excess of 40 nL/L were 14.0% and 13.9% at the urban and rural sites, respectively. AOT40 (accumulated ozone exposure over a threshold of 40 nL/L) values at the urban and rural forest sites were 0.968×10 h and 1.259×10 h, respectively. There was no significant difference in AOT40 values between the two sites.Our study demonstrated that near-ground ozone concentration in the rural forest was generally higher than that in the urban forest. However, there was no significant difference during summer in the city of Nanjing, the season when plants grow vigorously and are susceptible to damage from near-ground ozone concentrations. We conclude that the disturbance of plant growth from variation of near-ground ozone concentrations between the urban and rural sites was negligible in the urban space-for-time substitution experiments. 参考文献 相似文献 引证文献

Control of the dynamics of tropospheric ozone through the stratosphere

We consider two possible mechanisms of stratospheric control of the ozone concentration and dynamics in the troposphere. The first mechanism is implemented through the total-ozone-caused modulation of the ultraviolet radiative flux, incoming to the troposphere and initiating therein the photochemical processes. The second mechanism acts through direct transport of stratospheric ozone, which will “trigger” the photolysis and initiate these same processes of ozone generation, but now in the troposphere. Both of these mechanisms of stratospheric ozone control of the near-ground ozone concentration are shown to be apparent near Tomsk. It is noteworthy that the control via ultraviolet flux determines the amplitude modulation, and the transport from the stratosphere to the troposphere drives the temporal modulation.

Optimal structure of a network for near-ground ozone measurements in large industrial zones

Optimal structure of a network for near-ground ozone measurements in large industrial zones

Near-ground ozone source attributions and outflow in central eastern China during MTX2006

Abstract. A 3-D regional chemical transport model, the Nested Air Quality Prediction Model System (NAQPMS), with an on-line tracer tagging module was used to study the source of the near-ground (&lt;1.5 km above ground level) ozone at Mt. Tai (36.25° N, 117.10° E, 1534 m a.s.l.) in Central Eastern China (CEC) during the Mount Tai eXperiment 2006 (MTX2006). The model reproduced the temporal and spatial variations of near-ground ozone and other pollutants, and it captured highly polluted and clean cases well. The simulated near-ground ozone level over CEC was 60–85 ppbv (parts per billion by volume), which was higher than values in Japan and over the North Pacific (20–50 ppbv). The simulated tagged tracer data indicated that the regional-scale transport of chemically produced ozone over other areas in CEC contributed to the greatest fraction (49%) of the near-ground mean ozone at Mt. Tai in June; in situ photochemistry contributed only 12%. Due to high anthropogenic and biomass burning emissions that occurred in the southern part of the CEC, the contribution to ground ozone levels from this area played the most important role (32.4 ppbv, 37.9% of total ozone) in the monthly mean ozone concentration at Mt. Tai; values reached 59 ppbv (62%) on 6–7 June 2006. The monthly mean horizontal distribution of chemically produced ozone from various ozone production regions indicated that photochemical reactions controlled the spatial distribution of O3 over CEC. The regional-scale transport of pollutants also played an important role in the spatial and temporal distribution of ozone over CEC. Chemically produced ozone from the southern part of the study region can be transported northeastwardly to the northern rim of CEC; the mean contribution was 5–10 ppbv, and it reached 25 ppbv during high ozone events. Studies of the outflow of CEC ozone and its precursors, as well as their influences and contributions to the ozone level over adjacent regions/countries, revealed that the contribution of CEC ozone to mean ozone mixing ratios over the Korean Peninsula and Japan was 5–15 ppbv, of which about half was due to the direct transport of ozone from CEC and half was produced locally by ozone precursors transported from CEC.

Multiwavelength procedure for determining the concentration of near-ground ozone by an optical open-path measurement system

We present a theoretical basis and develop a convenient mathematical formalism for carrying out a multiwavelength procedure for measuring the concentration of near-ground ozone by the differential optical absorption spectroscopy (DOAS) open-path method. We have analyzed the effect on the measurement results from the difference between the spectra of the probing radiation traveling on the measurement path and the reference path.

Field surveys for potential ozone bioindicator plant species in Argentina

In Argentina no historical or present programs exist specifically assessing ecosystem health with respect to photochemical air pollution, although phytotoxic concentrations of near-ground ozone have been documented in recent years. Here we report our preliminary findings on field observations of ozone-like injury found in natural plant populations and agroecosystems late in the 2005 growing season in the Southern Hemisphere. Several possible ozone bioindicator plants which have not been previously documented were observed to exhibit foliar symptoms consistent with ozone-induced injury. Based on these results we intend to expand field surveys and complete the screening process for injury confirmation of the plant species described here. For this and future research we will be using controlled chamber studies based in the US. Continuous monitoring of tropospheric ozone does not currently take place in the region of central Argentina. The combined evidence provided by intermittent air quality sampling and the presence of ozone-like injury to vegetation indicates the need to establish air quality and ozone biomonitoring networks in this region.

Investigation on the spatial scales of the variability in measured near‐ground ozone mixing ratios

A quantitative measure for the spatial representativeness of ground level ozone concentrations is described and discussed as a means to compare modeled and measured data. It is derived from the analysis of the routinely measured diurnal variations of more than 300 German sites using principal component analysis. From the number of principal components (six) needed to explain the representative part of the time series (95%, up to the estimated error of the measurements) and the smallest correlation distance of these principal components we infer a radius of representativeness of about 4 km. This is a limit for the resolution of Eulerian models in order to simulate the representative part of the observations.

Variability of Near-Ground Ozone Concentrations During Cold Front Passages - a Possible Effect of Tropopause Folding Events

The analysis of surface ozone variability requires besides chemicalstudies the consideration of meteorological conditions and dynamicprocesses. Our research focuses on the mechanisms in connection with coldfront passages. A statistical study and case studies of cold front passageswere carried out at six German ground-based sites during the year 1990.After the passage of cold fronts three typical developments of thenear-ground ozone concentrations could be identified. Usually the ozoneconcentrations decrease due to advection of clean air masses or due toenhanced cloudiness preventing the photochemical production of ozone,chemical destruction by nitrogenoxides, and heterogeneous chemistry. In somecases the concentrations increased by reason of downward mixing of ozoneenriched air intruded from the stratosphere into the troposphere bytropopause foldings. For a few cases no modification set in. The decreasewas mostly twice as strong as the increase. The latter was between 4 and 8ppb on the average. Special emphasis is given to the transport ofstratospheric ozone down to the ground. There is no direct evidence forstratospheric ozone at ground level, because it can‘t be distinguished fromthe tropospheric one, but from case studies circumstantial evidence is foundin favour of it. As an example of increasing ozone behind the passage ofcold fronts one case study typical of all other case studies is presented.It shows the characteristic properties of the corresponding fronts, whichare fast movement, a vertical split structure and strong convection.