Haze events at different levels in winters: A comprehensive study of meteorological factors, Aerosol characteristics and direct radiative forcing in megacities of north and central China

Zhou, Ming; Jin, Shikuan; Ma, Yingying; Fan, Ruonan; Wang, Lunche; Gong, Wei; Liu, Boming

doi:10.1016/j.atmosenv.2020.118056

Cited by 19 publications

(10 citation statements)

References 75 publications

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“…PBLH at noon (06:00 UTC) is significantly higher than those at other times (the median is approximately 1 km), whilst PBLH results in the morning (00:00 UTC) and evening (12:00 UTC) are significantly lower than that at noon. This finding is attributed to the strong solar radiation at noon, causing the boundary layer to develop fully at daytime, whilst weak solar radiation leads to maintaining PBLH at a low level; the average height is approximately 0.5 km (Zhang et al, 2016). This finding is similar to that of Guo et al (2016), who indicated that PBLH is typically less than 1 km at daytime and less than 0.5 km at night.…”

Section: Intercomparison Of Pblh Resultssupporting

confidence: 74%

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Evaluation of retrieval methods for planetary boundary layer height based on radiosonde data

Liu

et al. 2021

Atmos. Meas. Tech.

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Abstract. Radiosonde (RS) is widely used to detect the vertical structures of the planetary boundary layer (PBL), and numerous methods have been proposed for retrieving PBL height (PBLH) from RS data. However, an algorithm that is suitable under all atmospheric conditions does not exist. This study evaluates the performance of four common PBLH algorithms under different thermodynamic stability conditions based on RS data collected from nine sites in January–December 2019. The four RS algorithms are the potential temperature gradient method (GMθ), relative humidity (RH) gradient method (GMRH), parcel method (PM) and Richardson number method (RM). Atmospheric conditions are divided into convective boundary layer (CBL), neutral boundary layer (NBL) and stable boundary layer (SBL) on the basis of the potential temperature profile. Results indicate that SBL is dominant at nighttime, whilst CBL dominates at daytime. Under all and SBL classifications, PBLH retrieved by RM is typically higher than those retrieved using the other methods. On the contrary, the PBLH result retrieved by PM is the lowest. Under CBL and NBL classifications, PBLH retrieved by PM is the highest. PBLH retrieved by GMθ and GMRH is relatively low under all classifications. Moreover, the uncertainty analysis shows that the consistency of PBLH retrieved by different algorithms is more than 80 % under CBL and NBL classifications. By contrast, the consistency of PBLH is less than 60 % under SBL classification. The average profiles and standard deviations of wind speed and potential temperature under consistent and inconsistent conditions are also investigated. The results indicate that consistent cases are typically accompanied by evident atmospheric stratification, such as a large gradient in the potential temperature profile or a low-level jet in the wind speed profile. These results indicate that the reliability of the PBLH results retrieved from RS data is affected by the structure of the boundary layer. Overall, GMθ and RM are appropriate for CBL condition. GMθ and PM are recommended for NBL condition. GMθ and GMRH are robust for SBL condition. This comprehensive comparison provides a reference for selecting the appropriate algorithm when retrieving PBLH from RS data.

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Section: Intercomparison Of Pblh Resultssupporting

confidence: 74%

“…SBL is formed via inversion stratification accompanied by ground radiation cooling. It typically occurs at night, and it is also known as the nocturnal boundary layer (Stull, 1988;Zhang et al, 2016Zhang et al, , 2020.…”

Section: Classification Of Thermodynamic Stability Conditionmentioning

confidence: 99%

Evaluation of retrieval methods for planetary boundary layer height based on radiosonde data

Liu

et al. 2021

Atmos. Meas. Tech.

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“…Under the two air conditions, ARF at BOA and ATM show a strong seasonal variation, that is, strongest in summer, followed by spring and autumn, and the weakest in winter, which mainly depends on the incident solar radiation and the aerosol load. [87], whereas relatively lower values and weaker seasonal variation of ARF at BOA were observed in urban Beijing, which is attributed to different driver factors of ARF [77,88]. In terms of the influence of different air conditions, the difference between ARF at TOA/BOA on clean-air days and on polluted-air days was the greatest in summer.…”

Section: Radiative Effects Of Total Atmospheric Aerosolsmentioning

confidence: 87%

“…In addition, it is worth noting that the scattered points in the areas with high PM 2.5 and low BC values in Figure 3a,d caused the low R 2 in spring and winter, revealing a dramatic change in the proportion of particles other than BC. This result may be related to the long-range transport of dust in spring and the water-soluble non-absorbing fine-mode particles in winter [75][76][77].…”

Section: Calculation Of Aerosol Radiative Forcingmentioning

confidence: 89%

Black Carbon over Wuhan, China: Seasonal Variations in Its Optical Properties, Radiative Forcing and Contribution to Atmospheric Aerosols

Fan

Jin

et al. 2021

Remote Sensing

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As an important fraction of light-absorbing particles, black carbon (BC) has a significant warming effect, despite accounting for a small proportion of total aerosols. A comprehensive investigation was conducted on the characteristics of atmospheric aerosols and BC particles over Wuhan, China. Mass concentration, optical properties, and radiative forcing of total aerosols and BC were estimated using multi-source observation data. Results showed that the BC concentration monthly mean varied from 2.19 to 5.33 μg m−3. The BC aerosol optical depth (AOD) maximum monthly mean (0.026) occurred in winter, whereas the maximum total AOD (1.75) occurred in summer. Under polluted-air conditions, both aerosol radiative forcing (ARF) and BC radiative forcing (BCRF) at the bottom of the atmosphere (BOA) were strongest in summer, with values of −83.01 and −11.22 W m−2, respectively. In summer, ARF at BOA on polluted-air days was more than two-fold that on clean-air days. In addition, compared with clean-air days, BCRF at BOA on polluted-air days was increased by 76% and 73% in summer and winter, respectively. The results indicate an important influence of particulate air pollution on ARF and BCRF. Furthermore, the average contribution of BCRF to ARF was 13.8%, even though the proportion of BC in PM2.5 was only 5.1%.

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“…The high aerosol and water vapour contents are the reasons why the clear-sky surface solar radiation in North China and the Yangtze River Delta in June are lower than those in May. ( Zhang et al, 2021 )Analyzed the Haze events at different levels in winters, they reached to this conclusion The occurrence of haze is found to be governed by the wind circulation and boundary layer in Beijing where the ground wind speed and the height of boundary layer decreased significantly with the development of haze. Compared with the boundary layer and wind, the relative humidity has a stronger impact on haze in Wuhan.…”

Section: Introductionmentioning

confidence: 99%

Impact of the inversion and air pollution on the number of patients with Covid-19 in the metropolitan city of Tehran

Keikhosravi

Fadavi

2021

Urban Climate

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Haze events at different levels in winters: A comprehensive study of meteorological factors, Aerosol characteristics and direct radiative forcing in megacities of north and central China

Cited by 19 publications

References 75 publications

Evaluation of retrieval methods for planetary boundary layer height based on radiosonde data

Evaluation of retrieval methods for planetary boundary layer height based on radiosonde data

Black Carbon over Wuhan, China: Seasonal Variations in Its Optical Properties, Radiative Forcing and Contribution to Atmospheric Aerosols

Impact of the inversion and air pollution on the number of patients with Covid-19 in the metropolitan city of Tehran

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