scholarly journals Interaction between aerosol and thermodynamic stability within the PBL during the wintertime over the North China Plain: Aircraft observation and WRF-Chem simulation

2021 ◽  
Author(s):  
Hao Luo ◽  
Li Dong ◽  
Yichen Chen ◽  
Yuefeng Zhao ◽  
Delong Zhao ◽  
...  
Keyword(s):  
Air Pollution ◽  
Vertical Distribution ◽  
North China Plain ◽  
North China ◽  
Thermal Structure ◽  
The North ◽  
The North China Plain ◽  
Vertical Distributions ◽  
Absorbing Aerosols

Abstract. Aerosol-planetary boundary layer (PBL) interaction has been proposed as a key mechanism for stabilizing the atmosphere and exacerbating surface air pollution. Although the understanding of this process has progressed enormously, its magnitude and impact remain uncertain and vary widely concerning aerosol types, vertical distributions, synoptic conditions, etc. In this study, our primary interest is to distinguish the aerosol-PBL interaction of absorbing and scattering aerosols under contrasting synoptic patterns and aerosol vertical distributions. Detailed in-situ aircraft (KingAir-350) measurements and online coupled model Weather Research and Forecasting with Chemistry (WRF-Chem) simulations are explored over the North China Plain (NCP). Furthermore, a long-term PBL stability trend from 1980 to 2020 over the NCP is also investigated. The aircraft measurements and surface observations show that the surface air pollution over the Baoding City on 3 January is heavier than that on 4 January, 2020. In addition, the aerosols are restricted to the low layer on 3 January, whereas the aerosols mix more homogeneous upwards on 4 January. Thereupon, we focus on the two days with distinct synoptic circumstances, PBL stability, and aerosol vertical distributions over the NCP. According to the WRF-Chem modelling, the synoptic pattern over the Baoding City differs between the two days. The prevailing wind direction is opposite with a southwest wind on 3 January and a northeast wind on 4 January. The results indicate that the synoptic condition may affect the PBL thermal structure, thus affecting the aerosol vertical distribution. Additionally, the sensitive numerical experiments reveal that the light-absorbing and light-scattering aerosols have different effects on altering the PBL thermal structure. The inhibition effect of scattering aerosols on the PBL appears to be independent of the aerosol height distribution and solely depends on its concentration. However, aerosol-PBL feedback of absorbing aerosols is highly dependent on its vertical distribution. Our analysis highlights that we should principally concentrate on controlling the emissions of scattering aerosols under the stable stratification while cooperating to control the emissions of scattering and absorbing aerosols in an unstable stratification. Moreover, the long-term inter-annual variation in PBL stability shows a strong correlation with the East Asian Winter Monsoon, which seems to be valuable in determining which pollutants to target in different monsoon years and attaining more precise air pollution control. Based on the numerical simulations and observational constraints, a concept scheme description has been concluded to deepen our recognition of the interactions between thermodynamic stability and aerosols within the PBL over the NCP region.

scholarly journals Impact of crop field burning and mountains on heavy haze in the North China Plain: A case study

2016 ◽  
Author(s):  
X. Long ◽  
X. X. Tie ◽  
J. J. Cao ◽  
R. J. Huang ◽  
T. Feng ◽  
...  
Keyword(s):  
Air Pollution ◽  
North China Plain ◽  
North China ◽  
Wind Condition ◽  
Beijing City ◽  
The North ◽  
The North China Plain ◽  
Crop Field ◽  
The Impact ◽  
Field Burning

Abstract. Crop field burning (CFB) has important effects on air pollution in China, but it is seldom quantified and reported in a regional scale, which is of great importance for the control strategies of CFB in China, especially in the North China Plain (NCP). With the provincial statistical data and open crop fires captured by satellite (MODIS), we extracted a detailed emission inventory of CFB during a heavy haze event from 6th to 12th October 2014. A regional dynamical and chemical model (WRF-Chem) was applied to investigate the impact of CFB on air pollution in NCP. The model simulations were compared with the in situ measurements of PM2.5 (particular matter with radius less than 2.5 μm) concentrations. The model evaluation shows that the correlation coefficients (R) between measured and calculated values exceeds 0.80 and absolute normalized mean bias (NMB) is no more than 14 %. In addition, the simulated meteorological parameters such as winds and planetary boundary layer height (PBLH) are also in good agreement with observations. The model was intensive used to study (1) the impacts of CFB and (2) the effect of mountains on regional air quality. The results show that the CFB occurred in southern NCP (SNCP) had significant effect on PM2.5 concentrations locally, causing a maximum of 35 % PM2.5 increase in SNCP. Because of south wind condition, the CFB pollution plume is subjective a long transport to northern NCP (NNCP-with several mega cities, including Beijing of the capital city in China), where there are no significant CFB occurrences, causing a maximum of 32 % PM2.5 increase in NNCP. As a result, the heavy haze in Beijing is enhanced by the CFB occurred in SNCP. Further more, there are two major mountains located in the western and northern NCP. Under the south wind condition, these mountains play important roles in enhancing the PM2.5 pollution in NNCP through the blocking and guiding effects. This study suggests that the PM2.5 emissions in SNCP region should be significantly limited in order to reduce the occurrences of heavy haze events in NNCP region, including the Beijing City.

scholarly journals Relationships between the planetary boundary layer height and surface pollutants derived from lidar observations over China

2018 ◽  
Author(s):  
Tianning Su ◽  
Zhanqing Li ◽  
Ralph Kahn
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Negative Correlation ◽  
North China Plain ◽  
North China ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
The North ◽  
The North China Plain

Abstract. The frequent occurrence of severe air pollution episodes in China has raised great concerns with the public and scientific communities. Planetary boundary layer height (PBLH) is a key factor in the vertical mixing and dilution of near-surface pollutants. However, the relationship between PBLH and surface pollutants, especially particulate matter (PM) concentration, across the whole of China, is not yet well understood. We investigate this issue at ~ 1500 surface stations using PBLH derived from space-borne and ground-based lidar, and discuss the influence of topography and meteorological variables on the PBLH-PM relationship. A generally negative correlation is observed between PM and the PBLH, albeit varying greatly in magnitude with location and season. Correlations are much weaker over the highlands than plains regions, which may be associated with lower pollution levels and mountain breezes. The influence of horizontal transport on surface PM is considered as well, manifested as a negative correlation between surface PM and wind speed over the whole nation. Strong wind with clean upwind sources plays a dominant role in removing pollutants, and leads to weak PBLH-PM correlation. A ventilation rate is introduced to jointly consider horizontal and vertical dispersion, which has the largest impact on surface pollutant accumulation over the North China Plain. Aerosol absorption feedbacks also appear to affect the PBLH-PM relationship, as revealed via comparing air pollution in Beijing and Hong Kong. Absorbing aerosols in high concentrations likely contribute to the significant PBLH-PM correlation over the North China Plain (e.g., during winter). As major precursor emissions for secondary aerosols, sulfur dioxide, nitrogen dioxide, and carbon monoxide have similar negative responses to increased PBLH, whereas ozone is positively correlated with PBLH over most regions, which may be caused by heterogeneous reactions and photolysis rates.

scholarly journals Contrasting Impacts of Long-Term Application of Biofertilizers and Organic Manure on Grain Yield of Winter Wheat in North China Plain

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 312 ◽  
Author(s):  
Amara Cisse ◽  
Adnan Arshad ◽  
Xiaofen Wang ◽  
Fanta Yattara ◽  
Yuegao Hu
Keyword(s):  
Grain Yield ◽  
North China Plain ◽  
North China ◽  
Farm Yard Manure ◽  
Grain Yields ◽  
The North ◽  
The North China Plain ◽  
Pig Farm ◽  
1000 Grain Weight

The effects of long-term incorporation of organic manure and biofertilizers have been investigated on winter wheat in the North China Plain (NCP). The five-year field experiment (2013–2018) has illustrated the responses of grain yield and yield components. Seven fertilization approaches, included pig farm-yard-manure and biofertilizers amendments combined with five NPK% drop levels of chemical fertilizer ratio + organic fertilizer + biofertilizer (0, C+O+B) 25%, CL4; 50%, CL3; 75%, CL1; and 100%, CL0), without fertilizer as control (CK), in NCP during the years 2013–2018. Results showed that the grain yields of CL1 and CL2 were equivalent to CL0 in all growing seasons except 2014/2015. The grain yields of CL4 were 29.9% to 46.6% lower than that of CL0 during 2014/2015, 2016/2017, and 2017/2018. The valuable spike-number, grain number per-spike, and 1000-grain weight showed significant variations among different growing periods. Regression analysis of grain yield and yield components indicated that number grains per-spike showed significant increase in seed yield formation. The 1000-grain weight was the major parameter that influenced yield of moderate and low yielding periods, respectively. The results revealed that application of 30 m3 ha−1 pig farm-yard-manure and 20 kg ha−1 biofertilizers has reduced at least 50% of the NPK fertilization without dropping grain yields in the North China Plain.

Carbon sequestration and mineralization in soil aggregates under long-term conservation tillage in the North China Plain

CATENA ◽  
2020 ◽  
Vol 188 ◽  
pp. 104428 ◽  
Author(s):  
Zheng-Rong Kan ◽  
Shou-Tian Ma ◽  
Qiu-Yue Liu ◽  
Bing-Yang Liu ◽  
Ahmad Latif Virk ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
North China Plain ◽  
North China ◽  
Conservation Tillage ◽  
Soil Aggregates ◽  
The North ◽  
The North China Plain

scholarly journals Measurement report: Variations in surface SO<sub>2</sub> and NO<sub>x</sub> mixing ratios from 2004 to 2016 at a background site in the North China Plain

2022 ◽  
Author(s):  
Xueli Liu ◽  
Liang Ran ◽  
Weili Lin ◽  
Xiaobin Xu ◽  
Zhiqiang Ma ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Diurnal Variations ◽  
Nox Emission ◽  
Mixing Ratios ◽  
The North ◽  
The North China Plain ◽  
Regional Background ◽  
Long Term Trends

Abstract. Strict air pollution control strategies have been implemented in recent decades in the North China Plain (NCP), previously one of the most polluted regions in the world, and have resulted in considerable changes in emissions of air pollutants. However, little is so far known about the long-term trends of the regional background level of NOx and SO2, along with the increase and decrease processes of regional emissions. In this study, the seasonal and diurnal variations of NOx and SO2 as well as their long-term trends at a regional background station in the NCP were characterized from 2004 to 2016. On average, SO2 and NOx mixing ratios were 5.7 ± 8.4 ppb and 14.2 ± 12.4 ppb, respectively. The seasonal variations in SO2 and NOx mixing ratios showed a similar pattern with a peak in winter and a valley in summer. However, the diurnal variations in SO2 and NOx mixing ratios greatly differed for all seasons, indicating different sources for SO2 and NOx. Overall, the annual mean SO2 exhibited a significant decreasing trend of ‒6.1 % yr−1 (R = −0.84, P < 0.01) from 2004 to 2016, which is very close to −6.3 % yr−1 of the annual SO2 emission in Beijing, and a greater decreasing trend of −7.4 % yr−1 (R = −0.95, P < 0.01) from 2008 to 2016. The annual mean of NOx showed a fluctuating rise of +3.4 % yr−1 (R = 0.38, P = 0.40) from 2005 to 2010, reaching the peak value (16.9 ppb) in 2010, and then exhibited an extremely significant fluctuating downward trend of −4.5 % yr−1 (R = 0.95, P < 0.01) from 2010 to 2016. After 2010, the annual mean NOx mixing ratios correlated significantly (R = 0.94, P < 0.01) with the annual NOx emission in North China. The decreasing rate (−4.8 % yr−1, R = −0.92, P < 0.01) of the annual mean NOx mixing ratios from 2011 to 2016 at SDZ are lower than the one (−8.8 % yr−1, R = −0.94, P < 0.01) for the annual NOx emission in the NCP and (−9.0 % yr−1, R = −0.96, P < 0.01) in Beijing. It indicated that surface NOx mixing ratios at SDZ had weaker influence than SO2 by the emission reduction in Beijing and its surrounding areas in the NCP. The increase in the amount of motor vehicles led to an increase in traffic emissions for NOx. This study supported conclusions from previous studies that the measures taken for controlling NOx and SO2 in the NCP in the past decades were generally successful. However, NOx emission control should be strengthened in the future.

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