scholarly journals Land-surface forcing and anthropogenic heat modulate ozone by meteorology: A perspective from the Yangtze River Delta region

2021 ◽  
Author(s):  
Chenchao Zhan ◽  
Min Xie
Keyword(s):  
Land Surface ◽  
Meteorological Factors ◽  
Vertical Mixing ◽  
Sea Breeze ◽  
Yangtze River Delta ◽  
Anthropogenic Heat ◽  
Lake Breeze ◽  
Surface O3 ◽  
The Yangtze River Delta ◽  
Pollution Episodes

Abstract. With the rapid advance in urbanization, land-surface forcing related to the urban expansion and anthropogenic heat (AH) release from human activities significantly affect the urban climate and in turn the air quality. Focusing on the Yangtze River Delta (YRD) region, a highly urbanized place with sever ozone (O3) pollution and complex geography, we estimate the impacts of land-surface forcing and AH on meteorology (meteorological factors and local circulations) and O3 using the WRF-chem model, which can enhance our understanding about the formation of O3 pollution in those rapidly developing regions with unique geographical features as most of our results can be supported by previous studies conducted in other regions in the world. Regional O3 pollution episodes occur frequently (26 times per year) in the YRD in recent years. These O3 pollution episodes are usually under calm conditions characterized by high temperature (over 20 °C), low relative humidity (less than 80 %), light wind (less than 3 m s−1) and shallow cloud cover (less than 5). In this case, high O3 mainly appears during the daytime influenced by the local circulations (the sea and the lake breezes). The change in land-surface forcing can cause an increase in 2-m temperature (T2) by maximum 3 °C, an increase in planetary boundary layer height (PBLH) by maximum 500 m and a decrease in 10-m wind speed (WS10) by maximum 1.5 m s−1, and surface O3 can increase by maximum 20 μg m−3 eventually. Furthermore, the expansion of coastal cities enhances the sea-breeze below 500 m. During the advance of the sea-breeze front inland, the upward air flow induced by the front makes well vertical mixing of O3. However, once the sea-breeze is fully formed, further progression inland is stalled, thus the O3 removal by the low sea-breeze will be weakened and surface O3 can be 10 μg m−3 higher in the case with cities than no-cities. The expansion of lakeside cities can extend the lifetime of the lake-breeze from the noon to the afternoon. Since the net effect of the lake-breeze is to accelerate the vertical mixing in the boundary layer, the surface O3 can increase as much as 30 μg m−3 in lakeside cities. Compared with the effects from land-surface forcing, the impacts of AH are relatively small. And the changes mainly appear in and around cities where AH emission is large. There are increases in T2, PBLH, WS10 and surface O3 when AH are taken into account, with the increment about 0.2 °C, 75 m, 0.3 m s−1 and 4 μg m−3, respectively. Additionally, AH can affect the urban-breeze circulations, meteorological factors and O3 concentration, but its effect on local circulations, such as the sea and the lake breezes, seems to be limited.

scholarly journals Modeling of the anthropogenic heat flux and its effect on regional meteorology and air quality over the Yangtze River Delta region, China

2016 ◽  
Vol 16 (10) ◽  
pp. 6071-6089 ◽  
Author(s):  
Min Xie ◽  
Jingbiao Liao ◽  
Tijian Wang ◽  
Kuanguang Zhu ◽  
Bingliang Zhuang ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
Vertical Movement ◽  
Anthropogenic Heat ◽  
The Yangtze River ◽  
The Yrd ◽  
Surface O3 ◽  
The Yangtze River Delta

Abstract. Anthropogenic heat (AH) emissions from human activities caused by urbanization can affect the city environment. Based on the energy consumption and the gridded demographic data, the spatial distribution of AH emission over the Yangtze River Delta (YRD) region is estimated. Meanwhile, a new method for the AH parameterization is developed in the WRF/Chem model, which incorporates the gridded AH emission data with the seasonal and diurnal variations into the simulations. By running this upgraded WRF/Chem for 2 typical months in 2010, the impacts of AH on the meteorology and air quality over the YRD region are studied. The results show that the AH fluxes over the YRD have been growing in recent decades. In 2010, the annual-mean values of AH over Shanghai, Jiangsu and Zhejiang are 14.46, 2.61 and 1.63 W m−2, respectively, with the high value of 113.5 W m−2 occurring in the urban areas of Shanghai. These AH emissions can significantly change the urban heat island and urban-breeze circulations in the cities of the YRD region. In Shanghai, 2 m air temperature increases by 1.6 °C in January and 1.4 °C in July, the PBLH (planetary boundary layer height) rises up by 140 m in January and 160 m in July, and 10 m wind speed is enhanced by 0.7 m s−1 in January and 0.5 m s−1 in July, with a higher increment at night. The enhanced vertical movement can transport more moisture to higher levels, which causes the decrease in water vapor at ground level and the increase in the upper PBL (planetary boundary layer), and thereby induces the accumulative precipitation to increase by 15–30 % over the megacities in July. The adding of AH can impact the spatial and vertical distributions of the simulated pollutants as well. The concentrations of primary air pollutants decrease near the surface and increase at the upper levels, due mainly to the increases in PBLH, surface wind speed and upward air vertical movement. But surface O3 concentrations increase in the urban areas, with maximum changes of 2.5 ppb in January and 4 ppb in July. Chemical direct (the rising up of air temperature directly accelerates surface O3 formation) and indirect (the decrease in NOx at the ground results in the increase in surface O3) effects can play a significant role in O3 changes over this region. The meteorology and air pollution predictions in and around large urban areas are highly sensitive to the anthropogenic heat inputs, suggesting that AH should be considered in the climate and air quality assessments.

scholarly journals Modeling the Effects of Climate Change on Surface Ozone during Summer in the Yangtze River Delta Region, China

2019 ◽  
Vol 16 (9) ◽  
pp. 1528 ◽  
Author(s):  
Da Gao ◽  
Min Xie ◽  
Xing Chen ◽  
Tijian Wang ◽  
Chenchao Zhan ◽  
...  
Keyword(s):  
Yangtze River ◽  
Meteorological Factors ◽  
Yangtze River Delta ◽  
The Yangtze River ◽  
The South ◽  
Southerly Wind ◽  
The North ◽  
The Yrd ◽  
Surface O3 ◽  
The Yangtze River Delta

Future climate change can impact ozone concentrations by changing regional meteorological factors related to ozone (O3) pollution. To better understand the variations of meteorological factors and their effects on O3 formation processes under future climate conditions, we model the present and the future meteorology and air quality in summer over the Yangtze River Delta (YRD) region by using the Weather Research and Forecasting Model with Chemistry module (WRF/Chem), which is driven by the outputs of Community Climate System Model version 4 (CCSM4). The simulations predict that solar radiation, 2-m air temperature, and wind speed increase in the daytime over most of the YRD region. Absolute humidity and precipitation increase in the north and decrease in the south, while the planetary boundary layer height (PBLH) has an opposite change pattern displaying a decrease in the north and an increase in the south. The southerly wind will be strengthened in the daytime. At night, the change patterns of the meteorological factors are similar to the daytime but with small variations. Meanwhile, O3 and its precursors all increase in the north and decrease in the south. The increases of NOx, volatile organic compounds (VOC), and CO are related with the decreases of PBLH and the input effect of stronger southerly wind, while the decreases are attributed to the output effect of the stronger southerly wind. During the daytime, the increase of surface O3 in the north is dominated by the chemical processes related with the increases of solar radiation, air temperature, and O3 precursors. The decrease of surface O3 in the south is mainly caused by the transport process changing with the strengthened southerly wind. At night, the surface O3 changing the amplitude is less than the daytime. The less O3 variations at night can be attributed to an O3 titration reaction with NO, the changes in NOx concentrations, and the increases of nocturnal PBLH. With the aid of H2O2/HNO3, O3 formation in the YRD region is found to be easily affected by NOx in the future. The findings can help to understand the changing trend of O3 in the YRD region and can propose reasonable pollution control policies.

scholarly journals Modeling of the anthropogenic heat flux and its effect on air quality over the Yangtze River Delta region, China

2015 ◽  
Vol 15 (22) ◽  
pp. 32367-32412 ◽  
Author(s):  
M. Xie ◽  
J. Liao ◽  
T. Wang ◽  
K. Zhu ◽  
B. Zhuang ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
Vertical Movement ◽  
Anthropogenic Heat ◽  
The Yangtze River ◽  
The Yrd ◽  
Surface O3 ◽  
The Yangtze River Delta

Abstract. Anthropogenic heat (AH) emissions from human activities caused by urbanization can affect the city environment. Based on the energy consumption and the gridded demographic data, the spatial distribution of AH emission over the Yangtze River Delta (YRD) region is estimated. Meanwhile, a new method for the AH parameterization is developed in the WRF/Chem model, which incorporates the gridded AH emission data with the seasonal and the diurnal variations into the simulations. By running this upgraded WRF/Chem for two typical months in 2010, the impacts of AH on the meteorology and air quality over the YRD region are studied. The results show that the AH fluxes over YRD have been growing in recent decades. In 2010, the annual mean values of AH over Shanghai, Jiangsu and Zhejiang are 14.46, 2.61 and 1.63 W m−2 respectively, with the high values of 113.5 W m−2 occurring in the urban areas of Shanghai. These AH emissions can significantly change the urban heat island and urban-breeze circulations in the cities of the YRD region. In Shanghai, 2 m air temperature increases by 1.6 °C in January and 1.4 °C in July, the planetary boundary layer height rises up by 140 m in January and 160 m in July, and 10 m wind speed is enhanced by 0.7 m s−1 in January and 0.5 m s−1 in July, with higher increment at night. And the enhanced vertical movement can transport more moisture to higher levels, which causes the decrease of water vapor at the ground level and the increase in the upper PBL, and thereby induces the accumulative precipitation to increase by 15–30 % over the megacities in July. The adding AH can impact the spatial and vertical distributions of the simulated pollutants as well. The concentrations of primary air pollutants decrease near surface and increase at the upper levels, due mainly to the increases of PBLH, surface wind speed and upward air vertical movement. But surface O3 concentrations increase in the urban areas, with maximum changes of 2.5 ppb in January and 4 ppb in July. Chemical direct (the rising up of air temperature directly accelerate surface O3 formation) and indirect (the decrease in NOx at the ground results in the increase of surface O3) effects can play a significant role in O3 changes over this region. The meteorology and air pollution predictions in and around large urban areas are highly sensitive to the anthropogenic heat inputs, suggesting that AH should be considered in any climate and air quality assessment.

scholarly journals Spatio-Temporal Variations of CO2 Emission from Energy Consumption in the Yangtze River Delta Region of China and Its Relationship with Nighttime Land Surface Temperature

2020 ◽  
Vol 12 (20) ◽  
pp. 8388
Author(s):  
Juchao Zhao ◽  
Shaohua Zhang ◽  
Kun Yang ◽  
Yanhui Zhu ◽  
Yuling Ma
Keyword(s):  
Surface Temperature ◽  
Co2 Emissions ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
The Yangtze River ◽  
Delta Region ◽  
Yangtze River Delta Region ◽  
The Yangtze River Delta

The rapid development of industrialization and urbanization has resulted in a large amount of carbon dioxide (CO2) emissions, which are closely related to the long-term stability of urban surface temperature and the sustainable development of cities in the future. However, there is still a lack of research on the temporal and spatial changes of CO2 emissions in long-term series and their relationship with land surface temperature. In this study, Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) data, Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) composite data, energy consumption statistics data and nighttime land surface temperature are selected to realize the spatial informatization of long-term series CO2 emissions in the Yangtze River Delta region, which reveals the spatial and temporal dynamic characteristics of CO2 emissions, spatial autocorrelation distribution patterns and their impacts on nighttime land surface temperature. According to the results, CO2 emissions in the Yangtze River Delta region show an obvious upward trend from 2000 to 2017, with an average annual growth rate of 6.26%, but the growth rate is gradually slowing down. In terms of spatial distribution, the CO2 emissions in that region have significant regional differences. Shanghai, Suzhou and their neighboring cities are the main distribution areas with high CO2 emissions and obvious patch distribution patterns. From the perspective of spatial trend, the areas whose CO2 emissions are of significant growth, relatively significant growth and extremely significant growth account for 8.78%, 4.84% and 0.58%, respectively, with a spatial pattern of increase in the east and no big change in the west. From the perspective of spatial autocorrelation, the global spatial autocorrelation index of CO2 emissions in the Yangtze River Delta region in the past 18 years has been greater than 0.66 (p < 0.01), which displays significant positive spatial autocorrelation characteristics, and the spatial agglomeration degree of CO2 emissions continues to increase from 2000 to 2010. From 2000 to 2017, the nighttime land surface temperature in that region showed a warming trend, and the areas where CO2 emissions are positively correlated with nighttime land surface temperature account for 88.98%. The increased CO2 emissions lead to, to a large extent, the rise of nighttime land surface temperature. The research results have important theoretical and practical significance for the Yangtze River Delta region to formulate a regional emission reduction strategy.

scholarly journals Simulating the Regional Impacts of Urbanization and Anthropogenic Heat Release on Climate across China

2012 ◽  
Vol 25 (20) ◽  
pp. 7187-7203 ◽  
Author(s):  
Jin-Ming Feng ◽  
Yong-Li Wang ◽  
Zhu-Guo Ma ◽  
Yong-He Liu
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Air Temperature ◽  
Yangtze River ◽  
Surface Air Temperature ◽  
Yangtze River Delta ◽  
Anthropogenic Heat ◽  
The Yangtze River ◽  
Regional Impacts ◽  
The Yangtze River Delta

Abstract Together with economic development and accelerated urbanization, the urban population in China has been increasing rapidly, and anthropogenic heat released by large-scale energy consumption in cities is expected to be a vital factor affecting the climate. In this paper, the Weather Research and Forecasting (WRF) model coupled with the Urban Canopy Model (UCM) is employed to simulate the regional impacts on climate under the two scenarios: the underlying surface changes due to urbanization (USCU) and anthropogenic heat release (AHR). Three experiments were performed from December 2006 to December 2008. With respect to the USCU, the surface albedo and the available surface soil water decrease markedly. With the inclusion of AHR, the two scenarios give rise to increased surface temperatures over most areas of China. Especially in the urban agglomeration area of the Yangtze River delta, the combination of USCU and AHR could result in an increase of 2°C in the surface air temperature. The influence of AHR on surface air temperature in winter is greater than the influence of USCU without considering any extra sources of heat, but the opposite is found in summer. The combination of USCU and AHR leads to changes in the surface energy budget. They both increase sensible heat flux, but USCU decreases latent heat flux significantly, and AHR increases latent heat flux slightly. Nevertheless, under the influence of these two scenarios, the precipitation increases in some areas, especially in the Beijing–Tianjin–Hebei region, while it decreases in other areas, most notably the Yangtze River delta.

scholarly journals An important mechanism of regional O<sub>3</sub> transport for summer smog over the Yangtze River Delta in eastern China

2018 ◽  
Vol 18 (22) ◽  
pp. 16239-16251 ◽  
Author(s):  
Jun Hu ◽  
Yichen Li ◽  
Tianliang Zhao ◽  
Jane Liu ◽  
Xiao-Ming Hu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Yangtze River ◽  
Eastern China ◽  
Yangtze River Delta ◽  
The Yangtze River ◽  
Convective Boundary ◽  
Summer Smog ◽  
The Yrd ◽  
Surface O3 ◽  
The Yangtze River Delta

Abstract. Severe ozone (O3) pollution episodes plague a few regions in eastern China at certain times of the year, e.g., the Yangtze River Delta (YRD). However, the formation mechanisms, including meteorological factors, contributing to these severe pollution events remain elusive. A severe summer smog stretched over the YRD region from 22 to 25 August 2016. This event displayed hourly surface O3 concentrations that exceeded 300 µg m−3 on 25 August in Nanjing, an urban area in the western YRD. The weather pattern during this period was characterized by near-surface prevailing easterly winds and continuous high air temperatures. The formation mechanism responsible for this O3 pollution episode over the YRD region, particularly the extreme values over the western YRD, was investigated using observation data and by running simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem). The results showed that the extremely high surface O3 concentration in the western YRD area on 25 August was largely due to regional O3 transport in the nocturnal residual layer (RL) and the diurnal change in the atmospheric boundary layer. On 24 August, high O3 levels, with peak values of 220 µg m−3, occurred in the daytime mixing layer over the eastern YRD region. During nighttime from 24 to 25 August, a shallow stable boundary layer formed near the surface which decoupled the RL above it from the surface. Ozone in the decoupled RL remained quite constant, which resulted in an O3-rich “reservoir” forming in this layer. This reservoir persisted due to the absence of O3 consumption from nitrogen oxide (NO) titration or dry deposition during nighttime. The prevailing easterly winds in the lower troposphere governed the regional transport of this O3-rich air mass in the nocturnal RL from the eastern to the western YRD. As the regional O3 transport reached the RL over the western YRD, O3 concentrations in the RL accumulated and rose to 200 µg m−3 over the western Nanjing site during the sunrise hours on 25 August. The development of the daytime convective boundary layer after sunrise resulted in the disappearance of the RL, as the vertical mixing in the convective boundary layer uniformly redistributed O3 from the upper levels via the entrainment of O3-rich RL air down to the O3-poor air at the ground. This net downward transport flux reached up to 35 µg m−3 h−1, and contributed a considerable surface O3 accumulation, resulting in severe daytime O3 pollution during the summer smog event on 25 August in the western YRD region. The mechanism of regional O3 transport through the nocturnal RL revealed in this study has great implications regarding understanding O3 pollution and air quality change.

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