Impact of planetary boundary layer structure on the formation and evolution of air-pollution episodes in Shenyang, Northeast China

Li, Xiaolan; Hu, Xiao‐Ming; Ma, Yanhui; Wang, Yangfeng; Li, Liguang; Zhao, Zhijun

doi:10.1016/j.atmosenv.2019.116850

Cited by 86 publications

(42 citation statements)

References 68 publications

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“…14). In terms of WRF, higher winter urban temperatures in simulations with the BEP+BEM urban scheme are consistent with results of previous studies (Liao et al, 2014;Karlický et al, 2018) and are probably caused by higher amounts of anthropogenic heat, internally computed within the scheme. In simulations with the bulk urban scheme, no anthropogenic heat is considered, and therefore the winter UHI is suppressed.…”

Section: Discussionsupporting

confidence: 89%

The “urban meteorology island”: a multi-model ensemble analysis

et al. 2020

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Abstract. Cities and urban areas are well-known for their impact on meteorological variables and thereby modification of the local climate. Our study aims to generalize the urban-induced changes in specific meteorological variables by introducing a single phenomenon – the urban meteorology island (UMI). A wide ensemble of 24 model simulations with the Weather Research and Forecasting (WRF) regional climate model and the Regional Climate Model (RegCM) on a European domain with 9 km horizontal resolution were performed to investigate various urban-induced modifications as individual components of the UMI. The results show that such an approach is meaningful, because in nearly all meteorological variables considered, statistically significant changes occur in cities. Besides previously documented urban-induced changes in temperature, wind speed and boundary-layer height, the study is also focused on changes in cloud cover, precipitation and humidity. An increase in cloud cover in cities, together with a higher amount of sub-grid-scale precipitation, is detected on summer afternoons. Specific humidity is significantly lower in cities. Further, the study shows that different models and parameterizations can have a strong impact on discussed components of the UMI. Multi-layer urban schemes with anthropogenic heat considered increase winter temperatures by more than 2 ∘C and reduce wind speed more strongly than other urban models. The selection of the planetary-boundary-layer scheme also influences the urban wind speed reduction, as well as the boundary-layer height, to the greatest extent. Finally, urban changes in cloud cover and precipitation are mostly sensitive to the parameterization of convection.

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Section: Discussionsupporting

confidence: 89%

The “urban meteorology island”: a multi-model ensemble analysis

et al. 2020

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“…Although great efforts have been devoted to elucidating the complex interactions between the PBL and aerosol pollution in China in recent years, most studies focused on Beijing, Shanghai, Guangzhou, and Chengdu, and the PBL structure/ process in the other megacities is still far from well known, especially for Central China. In addition to those 13 megacities listed in Table 1, the urban PBLs in other heavily polluted and densely populated cities in China also need further investigations, such as Zhengzhou [24•], Lanzhou [104], Xi'an [105], Harbin [24•], and Shenyang [106].…”

Section: Discussionmentioning

confidence: 99%

Interaction Between Planetary Boundary Layer and PM2.5 Pollution in Megacities in China: a Review

Miao

et al. 2019

Curr Pollution Rep

117

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Purpose of Review During the past decades, the number and size of megacities have been growing dramatically in China. Most of Chinese megacities are suffering from heavy PM 2.5 pollution. In the pollution formation, the planetary boundary layer (PBL) plays an important role. This review is aimed at presenting the current state of understanding of the PBL-PM 2.5 interaction in megacities, as well as to identify the main gaps in current knowledge and further research needs. Recent Findings The PBL is critical to the formation of urban PM 2.5 pollution at multiple temporal scales, ranging from diurnal change to seasonal variation. For the essential PBL structure/process in pollution, the coastal megacities have different concerns from the mountainous or landlocked megacities. In the coastal cities, the recirculation induced by sea-land breeze can accumulate pollutants, whereas in the valley/basin, the blocking effects of terrains can lead to stagnant conditions and thermal inversion. Within a megacity, although the urbanization-induced land use change can cause thermodynamic perturbations and facilitate the development of PBL, the increases in emissions outweigh this impact, resulting in a net increase of aerosol concentration. Moreover, the aerosol radiative effects can modify the PBL by heating the upper layers and reducing the surface heat flux, suppressing the PBL and exacerbating the pollution. Summary This review presented the PBL-PM 2.5 interaction in 13 Chinese megacities with various geographic conditions and elucidated the critical influencing processes. To further understand the complicated interactions, long-term observations of meteorology and aerosol properties with multi-layers in the PBL need to be implemented.

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“…Both model domains have 47 vertical layers extending from the surface to 10 hPa. The simulations ran continuously from 1 January to 31 December 2016 using spectral nudging and climatic downscaling techniques documented by Hu et al (2017, 2018, 2019b, 2020) and Li et al (2019). Temperature, geopotential height, and horizontal winds above the boundary layer at a ~1,000 km scale are spectrally nudged to the reanalysis data throughout the downscaling simulation, and variation of these variables over smaller scales are predicted by model dynamics.…”

Section: Methodsmentioning

confidence: 99%

Terrestrial CO₂ Fluxes, Concentrations, Sources and Budget in Northeast China: Observational and Modeling Studies

Cai

et al. 2020

JGR Atmospheres

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CO2 fluxes and concentrations are not well understood in Northeast China, where dominant land surface types are mixed forest and cropland. Here, we analyzed the CO2 fluxes and concentrations using observations and the Weather Research and Forecasting model coupled with the Vegetation Photosynthesis and Respiration Model (WRF‐VPRM). We also used WRF‐VPRM outputs to examine CO2 transport/dispersion and budgets. Finally, we investigated the uncertainties of simulating CO2 fluxes related to four VPRM parameters (including maximum light use efficiency, photosynthetically active radiation half‐saturation value, and two respiration parameters) using off‐line ensemble simulations. The results indicated that mixed forests acted as a larger CO2 source and sink than rice paddies in 2016 due to a longer growth period and stronger ecosystem respiration, although measured minimum daily mean net ecosystem exchange (NEE) was smaller at rice paddy (−10 μmol·m‐2·s‐1) than at mixed forest (−6.5 μmol·m‐2·s‐1) during the growing season (May–September). The monthly fluctuation of column‐averaged CO2 concentrations (XCO2) exceeded 10 ppm in Northeast China during 2016. The large summertime biogenic sinks offset about 70% of anthropogenic contribution of XCO2 in this region. WRF‐VPRM modeling successfully captured seasonal and episodic variations of NEE and CO2 concentrations; however, NEE in mixed forest was overestimated during daytime, mainly due to the uncertainties of VPRM parameters, especially maximum light use efficiency. These findings suggest that the WRF‐VPRM modeling framework will provide greater understanding of the natural and anthropogenic contributions to the carbon cycle in China, especially after calibration of parameters that control biogenic fluxes.

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Impact of planetary boundary layer structure on the formation and evolution of air-pollution episodes in Shenyang, Northeast China

Cited by 86 publications

References 68 publications

The “urban meteorology island”: a multi-model ensemble analysis

The “urban meteorology island”: a multi-model ensemble analysis

Interaction Between Planetary Boundary Layer and PM2.5 Pollution in Megacities in China: a Review

Terrestrial CO₂ Fluxes, Concentrations, Sources and Budget in Northeast China: Observational and Modeling Studies

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Impact of planetary boundary layer structure on the formation and evolution of air-pollution episodes in Shenyang, Northeast China

Cited by 86 publications

References 68 publications

The “urban meteorology island”: a multi-model ensemble analysis

The “urban meteorology island”: a multi-model ensemble analysis

Interaction Between Planetary Boundary Layer and PM2.5 Pollution in Megacities in China: a Review

Terrestrial CO2 Fluxes, Concentrations, Sources and Budget in Northeast China: Observational and Modeling Studies

Contact Info

Product

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Terrestrial CO₂ Fluxes, Concentrations, Sources and Budget in Northeast China: Observational and Modeling Studies