scholarly journals Integrated impacts of synoptic forcing and aerosol radiative effect on boundary layer and pollution in the Beijing–Tianjin–Hebei region, China

2020 ◽  
Vol 20 (10) ◽  
pp. 5899-5909 ◽  
Author(s):  
Yucong Miao ◽  
Huizheng Che ◽  
Xiaoye Zhang ◽  
Shuhua Liu
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Large Scale ◽  
Eastern China ◽  
Radiative Effect ◽  
Synoptic Pattern ◽  
Rapid Urbanization ◽  
Synoptic Conditions ◽  
Aerosol Pollution ◽  
Aerosol Radiative

Abstract. Rapid urbanization and industrialization have led to deterioration of air quality in the Beijing–Tianjin–Hebei (BTH) region due to high loadings of PM2.5. Heavy aerosol pollution frequently occurs in winter, in close relation to the planetary boundary layer (PBL) meteorology. To unravel the physical processes that influence PBL structure and aerosol pollution in BTH, this study combined long-term observational data analyses, synoptic pattern classification, and meteorology–chemistry coupled simulations. During the winter of 2017 and 2018, Beijing and Tangshan often experienced heavy PM2.5 pollution simultaneously, accompanied by strong thermal inversion aloft. These concurrences of pollution in different cities were primarily regulated by the large-scale synoptic conditions. Using principal component analysis with geopotential height fields at the 850 hPa level during winter, two typical synoptic patterns associated with heavy pollution in BTH were identified. One pattern is characterized by a southeast-to-north pressure gradient across BTH, and the other is associated with high pressure in eastern China. Both synoptic types feature warmer air temperature at 1000 m a.g.l., which could suppress the development of the PBL. Under these unfavorable synoptic conditions, aerosols can modulate PBL structure through the radiative effect, which was examined using numerical simulations. The aerosol radiative effect can significantly lower the daytime boundary layer height through cooling the surface layer and heating the upper part of the PBL, leading to the deterioration of air quality. This PBL–aerosol feedback is sensitive to the aerosol vertical structure, which is more effective when the synoptic pattern can distribute more aerosols to the upper PBL.

scholarly journals Integrated impacts of synoptic forcing and aerosol radiative effect on boundary layer and pollution in the Beijing-Tianjin-Hebei region, China

2019 ◽  
Author(s):  
Yucong Miao ◽  
Huizheng Che ◽  
Xiaoye Zhang ◽  
Shuhua Liu
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Large Scale ◽  
Radiative Effect ◽  
Synoptic Pattern ◽  
Rapid Urbanization ◽  
Near Surface ◽  
Thermal Inversion ◽  
Mountainous Regions ◽  
Aerosol Radiative

Abstract. Rapid urbanization and industrialization have led to deterioration of air quality in the Beijing-Tianjin-Hebei (BTH) region with high loadings of PM2.5. The heavy aerosol pollutions frequently occur in winter, closely in relation to the meteorological conditions. To unravel the complicated impacts of large-scale atmospheric forcing and the local-scale planetary boundary layer (PBL) characteristics on the pollution there, this study combined long-term observational data analyses, synoptic pattern classification, and meteorology-chemistry coupled simulations. During the winter of 2017 and 2018, Beijing, Langfang, Tianjin, and Tangshan often simultaneously experienced heavy PM2.5 pollution, accompanying with strong thermal inversion aloft. These concurrences of pollution in different cities were primarily regulated by the large-scale atmospheric processes. Using the principal component analysis with the geopotential height fields at the 850-hPa level during winter, the typical polluted synoptic pattern in BTH was identified. The pattern was featured by westerly winds from upstream mountainous regions. By inducing warm advections from the west, the thermal inversion aloft in the BTH could be enhanced, leading to shallow daytime PBLs and high near-surface PM2.5 concentrations. In addition, the aerosol may also modulate the PBL structure through its radiative effect, which was examined using numerical simulations. The aerosol radiative effect can significantly lower the boundary layer height in the afternoon through cooling the surface layer and heating the upper part of PBL. Thus, more aerosols could be accumulated in the lower portion of PBL, bringing about heavy pollution in the BTH. This study has revealed the important roles played by the meteorology-aerosol interaction on the air quality.

scholarly journals Classification of summertime synoptic patterns in Beijing and their associations with boundary layer structure affecting aerosol pollution

2017 ◽  
Vol 17 (4) ◽  
pp. 3097-3110 ◽  
Author(s):  
Yucong Miao ◽  
Jianping Guo ◽  
Shuhua Liu ◽  
Huan Liu ◽  
Zhanqing Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Large Scale ◽  
Layer Structure ◽  
Inversion Layer ◽  
Near Surface ◽  
Synoptic Patterns ◽  
Synoptic Conditions ◽  
Aerosol Pollution ◽  
Fine Resolution

Abstract. Meteorological conditions within the planetary boundary layer (PBL) are closely governed by large-scale synoptic patterns and play important roles in air quality by directly and indirectly affecting the emission, transport, formation, and deposition of air pollutants. Partly due to the lack of long-term fine-resolution observations of the PBL, the relationships between synoptic patterns, PBL structure, and aerosol pollution in Beijing have not been well understood. This study applied the obliquely rotated principal component analysis in T-mode to classify the summertime synoptic conditions over Beijing using the National Centers for Environmental Prediction reanalysis from 2011 to 2014, and investigated their relationships with PBL structure and aerosol pollution by combining numerical simulations, measurements of surface meteorological variables, fine-resolution soundings, the concentration of particles with diameters less than or equal to 2.5 µm, total cloud cover (CLD), and reanalysis data. Among the seven identified synoptic patterns, three types accounted for 67 % of the total number of cases studied and were associated with heavy aerosol pollution events. These particular synoptic patterns were characterized by high-pressure systems located to the east or southeast of Beijing at the 925 hPa level, which blocked the air flow seaward, and southerly PBL winds that brought in polluted air from the southern industrial zone. The horizontal transport of pollutants induced by the synoptic forcings may be the most important factor affecting the air quality of Beijing in summer. In the vertical dimension, these three synoptic patterns featured a relatively low boundary layer height (BLH) in the afternoon, accompanied by high CLD and southerly cold advection from the seas within the PBL. The high CLD reduced the solar radiation reaching the surface, and suppressed the thermal turbulence, leading to lower BLH. Besides, the numerical sensitive experiments show that cold advection induced by the large-scale synoptic forcing may have cooled the PBL, leading to an increase in near-surface stability and a decrease in the BLH in the afternoon. Moreover, when warm advection appeared simultaneously above the top level of the PBL, the thermal inversion layer capping the PBL may have been strengthened, resulting in the further suppression of PBL and thus the deterioration of aerosol pollution levels. This study has important implications for understanding the crucial roles that meteorological factors (at both synoptic and local scales) play in modulating and forecasting aerosol pollution in Beijing and its surrounding area.

scholarly journals Classification of summertime synoptic patterns in Beijing and their association with boundary layer structure affecting aerosol pollution

2016 ◽  
Author(s):  
Yucong Miao ◽  
Jianping Guo ◽  
Shuhua Liu ◽  
Huan Liu ◽  
Zhanqing Liu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Layer Structure ◽  
Inversion Layer ◽  
Principal Component ◽  
Near Surface ◽  
Synoptic Patterns ◽  
Synoptic Conditions ◽  
Aerosol Pollution ◽  
Fine Resolution

Abstract. Meteorological conditions within the planetary boundary layer (PBL) are closely governed by large-scale synoptic patterns and play important roles in air quality by directly and indirectly affecting the emission, transport, formation, and deposition of air pollutants. Partly due to the lack of long-term fine-resolution observations of the PBL, the relationships between synoptic patterns, PBL structure, and aerosol pollution in Beijing have not been well understood. This study applied the obliquely rotated principal component analysis in T-mode to classify the summertime synoptic conditions over Beijing using the National Centers for Environmental Prediction reanalysis from 2011 to 2014, and investigated their relationships with PBL structure and aerosol pollution by combining measurements of surface meteorological variables, fine-resolution soundings, the concentration of particles with diameters less than or equal to 2.5 μm, total cloud cover (CLD), and reanalysis data. Among the seven identified synoptic patterns, three types accounted for 67 % of the total number of cases studied and were associated with heavy aerosol pollution events. These particular synoptic patterns were characterized by high-pressure systems located to the east or southeast of Beijing at the 925-hPa level, which blocked the air flow seaward, and southerly PBL winds that brought in polluted air from the southern industrial zone. In the vertical dimension, these three synoptic patterns featured a relatively low boundary layer height (BLH) in the afternoon, accompanied by high CLD and southerly cold advection from the seas within the PBL. The cold advection induced by the large-scale synoptic forcing may have cooled the PBL, leading to an increase in near-surface stability and a decrease in the BLH in the afternoon. Moreover, when warm advection appeared simultaneously above the top level of the PBL, the thermal inversion layer capping the PBL may have been strengthened, resulting in further suppression of the PBL and deteriorating aerosol pollution levels. This study has important implications for understanding the crucial roles that meteorological factors (at both synoptic and local scales) play in modulating and forecasting aerosol pollution in Beijing and its surrounding area.

scholarly journals A Study on Parameterization of the Beijing Winter Heavy Haze Events Associated with Height of Pollution Mixing Layer

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Tao Niu ◽  
Jizhi Wang ◽  
Yuanqin Yang ◽  
Yaqiang Wang ◽  
Cheng Chen
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Large Scale ◽  
North China Plain ◽  
North China ◽  
Eastern China ◽  
Mixing Layer ◽  
Vertical Diffusion ◽  
Raising Awareness ◽  
Heavy Pollution

North China Plain, Beijing, Tianjin, and Hebei province are the major areas facing the decreasing air quality and frequent pollution events in the recent years. Identifying the effect of meteorological conditions on changes in aerosol concentration and the mechanism for forming such heavy pollution in North China Plain has become the focus of scientific research. The influence of atmospheric boundary layer characteristics on air quality has become the focus of attention and research. However, the boundary layer describes that the influences of air pollution have sometimes been duplicated and confused with each other in some of the studies. It is necessary to pay attention to some extent, raising awareness of related pollution mixing layer. The conclusions of the study include the following:(1)The lowered height of pollution mixing layer (H_PML) was favorable for the increase of the PM2.5density. The lowered height of pollution mixing layer had significant impacts on formation of severe haze.(2)A statistical analysis of large-scale heavy pollution cases in eastern China shows that the H_PML parameters have significant contributions.(3)The feedback effect of the high value of the convection inhibition (CIN), which is unfavorable to vertical diffusion of pollution, causes further reduction of H_PML, resulting in cumulative pollution again.

scholarly journals Spatial and Temporal Characteristics of Environmental Air Quality and Its Relationship with Seasonal Climatic Conditions in Eastern China during 2015–2018

2021 ◽  
Vol 18 (9) ◽  
pp. 4524
Author(s):  
Zhiyuan Wang ◽  
Xiaoyi Shi ◽  
Chunhua Pan ◽  
Sisi Wang
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Air Pollutants ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Eastern China ◽  
Climatic Conditions ◽  
Uniform Structure ◽  
Concentration Limit ◽  
Environmental Air

Exploring the relationship between environmental air quality (EAQ) and climatic conditions on a large scale can help better understand the main distribution characteristics and the mechanisms of EAQ in China, which is significant for the implementation of policies of joint prevention and control of regional air pollution. In this study, we used the concentrations of six conventional air pollutants, i.e., carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), fine particulate matter (PM2.5), coarse particulate matter (PM10), and ozone (O3), derived from about 1300 monitoring sites in eastern China (EC) from January 2015 to December 2018. Exploiting the grading concentration limit (GB3095-2012) of various pollutants in China, we also calculated the monthly average air quality index (AQI) in EC. The results show that, generally, the EAQ has improved in all seasons in EC from 2015 to 2018. In particular, the concentrations of conventional air pollutants, such as CO, SO2, and NO2, have been decreasing year by year. However, the concentrations of particulate matter, such as PM2.5 and PM10, have changed little, and the O3 concentration increased from 2015 to 2018. Empirical mode decomposition (EOF) was used to analyze the major patterns of AQI in EC. The first mode (EOF1) was characterized by a uniform structure in AQI over EC. These phenomena are due to the precipitation variability associated with the East Asian summer monsoon (EASM), referred to as the “summer–winter” pattern. The second EOF mode (EOF2) showed that the AQI over EC is a north–south dipole pattern, which is bound by the Qinling Mountains and Huaihe River (about 35° N). The EOF2 is mainly caused by seasonal variations of the mixed concentration of PM2.5 and O3. Associated with EOF2, the Mongolia–Siberian High influences the AQI variation over northern EC by dominating the low-level winds (10 m and 850 hPa) in autumn and winter, and precipitation affects the AQI variation over southern EC in spring and summer.

Regional Downscaling for Air Quality Assessment

2007 ◽  
Vol 88 (8) ◽  
pp. 1215-1228 ◽  
Author(s):  
William I. Gustafson ◽  
L. Ruby Leung
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Quality Assessment ◽  
Large Scale ◽  
Dynamical Downscaling ◽  
Circulation Model ◽  
The United States ◽  
Climate Simulation ◽  
Large Scale Circulation ◽  
Air Quality Assessment

Assessing future changes in air quality using downscaled climate scenarios is a relatively new application of the dynamical downscaling technique. This article compares and evaluates two downscaled simulations for the United States made using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model with the goal of understanding how errors in the downscaled climate simulations may introduce uncertainty in air quality assessment. The two downscaled simulations were driven by boundary conditions from the NCEP–NCAR global reanalysis and a global climate simulation generated by the Goddard Institute for Space Studies global circulation model, respectively. Comparisons of the model runs are made against the boundary layer and circulation characteristics of the North American Regional Reanalysis, and also against observed precipitation. The relative dependence of different simulated quantities on regional forcing, model parameterizations, and large-scale circulation provides a framework to understand similarities and differences between model simulations. Results show significant improvements in the downscaled diurnal wind patterns, in response to the complex orography, that are important for air quality assessment. Evaluation of downscaled boundary layer depth and winds, precipitation, and large-scale circulation shows larger biases related to model physics and biases in the GCM large-scale conditions. Based on the comparisons, recommendations are made to improve the utility of downscaled scenarios for air quality assessment.

scholarly journals Coastal Landscape Vulnerability Analysis in Eastern China—Based on Land-Use Change in Jiangsu Province

2020 ◽  
Vol 17 (5) ◽  
pp. 1702
Author(s):  
Yangfan Zhou ◽  
Lijie Pu ◽  
Ming Zhu
Keyword(s):  
Land Use ◽  
Human Activities ◽  
Large Scale ◽  
Positive Impact ◽  
Eastern China ◽  
Landscape Management ◽  
Vulnerability Index ◽  
Jiangsu Province ◽  
Assessment Model ◽  
Rapid Urbanization

The unreasonable land use in rapid urbanization areas induced by large-scale urban construction activities have caused massive ecological issues. In this study, landscape vulnerability index (LVI) and landscape human interference index (LHAI) were originally addressed and calculated using multi-temporal land-use data from 2000 to 2015. Then, the spatial-temporal relationship assessment model of landscape fragility caused by human activities were constructed for each county of Jiangsu Province, China, so as to analyze the spatial distribution of landscape vulnerability and determine the impacts of artificial disturbance on landscape vulnerability. The results showed: (1) The number of counties with middle and high landscape vulnerability increased from 20 in 2000 to 27 in 2015 with a peak value (33) in 2010. (2) Counties with high-intensity human activities showed an upward trend. (3) Land use generally has a significant and diverse impact on landscape vulnerability. At the county level, the LVI was positively correlated with the LHAI before 2010 and was followed by a negative correlation of them. As concluded from this study, a total of four sub-regions (continuous benefit zones, variable benefit zones, continuous harmful zones, and variable harmful zones) have been identified for sustainable landscape management in the future. (4) The LVI suggests that the landscape vulnerability in Jiangsu did not continue to deteriorate in the study period. Further, accelerated land exploitation has produced a positive impact on regional economic development and ecological protection. This study provided an effective method set for analyzing the environmental impacts caused by human activities and promoting future ecosystem management in coastal areas.

scholarly journals Large-Scale Atmospheric Forcing by Southeast Pacific Boundary Layer Clouds: A Regional Model Study*

2005 ◽  
Vol 18 (7) ◽  
pp. 934-951 ◽  
Author(s):  
Yuqing Wang ◽  
Shang-Ping Xie ◽  
Bin Wang ◽  
Haiming Xu
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Inversion Layer ◽  
Regional Model ◽  
Cloud Layer ◽  
Eastern Pacific ◽  
Radiative Effect ◽  
Boundary Layer Clouds ◽  
Southeast Pacific ◽  
Stratocumulus Clouds

Abstract A regional model is used to study the radiative effect of boundary layer clouds over the southeast Pacific on large-scale atmosphere circulation during August–October 1999. With the standard settings, the model simulates reasonably well the large-scale circulation over the eastern Pacific, precipitation in the intertropical convergence zone (ITCZ) north of the equator, and marine boundary layer stratocumulus clouds to the south. In a sensitivity experiment with the radiative effect of liquid clouds south of the equator over the eastern Pacific artificially removed, boundary layer clouds south of the equator almost disappear and precipitation in the ITCZ is reduced by 15%–20%, indicating that the stratocumulus clouds over the southeast Pacific have both local and cross-equatorial effects. Examination of the differences between the control and sensitivity experiments indicates that clouds exert a net diabatic cooling in the inversion layer. In response to this cloud-induced cooling, an in situ anomalous high pressure system develops in the boundary layer and an anomalous shallow meridional circulation develops in the lower troposphere over the equatorial eastern Pacific. At the lower branch of this shallow circulation, anomalous boundary layer southerlies blow from the boundary layer high toward the northern ITCZ where the air ascends. An anomalous returning flow (northerly) just above the cloud layer closes the shallow circulation. This low-level anomalous shallow circulation enhances the subsidence over the southeast Pacific above the cloud layer, helping to maintain boundary layer clouds and temperature inversion there. Meanwhile, the strengthened cross-equatorial flow near the surface enhances moisture convergence and convection in the ITCZ north of the equator. This in turn strengthens the local, deep Hadley circulation and hence the large-scale subsidence and boundary layer clouds over the southeast Pacific. This positive feedback therefore enhances the interhemispheric climate asymmetry over the tropical eastern Pacific.

scholarly journals Associations between Weather, Air Quality and Moderate Extreme Cancer-Related Mortality Events in Augsburg, Southern Germany

2021 ◽  
Vol 18 (22) ◽  
pp. 11737
Author(s):  
Patrick Olschewski ◽  
Irena Kaspar-Ott ◽  
Stephanie Koller ◽  
Gerhard Schenkirsch ◽  
Martin Trepel ◽  
...  
Keyword(s):  
High Pressure ◽  
Air Quality ◽  
Large Scale ◽  
Regional Scale ◽  
Late Winter ◽  
Southern Germany ◽  
Atmospheric Processes ◽  
Synoptic Conditions ◽  
Depth Analysis ◽  
Related Mortality

While many authors have described the adverse health effects of poor air quality and meteorological extremes, there remain inconsistencies on a regional scale as well as uncertainty about the single and joint effects of atmospheric predictors. In this context, we investigated the short-term impacts of weather and air quality on moderate extreme cancer-related mortality events for the urban area of Augsburg, Southern Germany, during the period 2000–2017. First, single effects were uncovered by applying a case-crossover routine. The overall impact was assessed by performing a Mann–Whitney U testing scheme. We then compared the results of this procedure to extreme noncancer-related mortality events. In a second step, we found periods with contemporaneous significant predictors and carried out an in-depth analysis of these joint-effect periods. We were interested in the atmospheric processes leading to the emergence of significant conditions. Hence, we applied the Principal Component Analysis to large-scale synoptic conditions during these periods. The results demonstrate a strong linkage between high-mortality events in cancer patients and significantly above-average levels of nitrogen dioxide (NO2) and particulate matter (PM2.5) during the late winter through spring period. These were mainly linked to northerly to easterly weak airflow under stable, high-pressure conditions. Especially in winter and spring, this can result in low temperatures and a ground-level increase and the accumulation of air pollution from heating and traffic as well as eastern lateral advection of polluted air. Additionally, above-average temperatures were shown to occur on the days before mortality events from mid-summer through fall, which was also caused by high-pressure conditions with weak wind flow and intense solar radiation. Our approach can be used to analyse medical data with epidemiological as well as climatological methods while providing a more vivid representation of the underlying atmospheric processes.

An observational study of the boundary-layer entrainment and impact of aerosol radiative effect under aerosol-polluted conditions

2020 ◽  
pp. 105348
Author(s):  
Cheng Liu ◽  
Jianping Huang ◽  
Xinyu Tao ◽  
Lichen Deng ◽  
Xiaozhen Fang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Observational Study ◽  
Radiative Effect ◽  
Aerosol Radiative
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