The impact of large-scale circulation on daily fine particulate matter (PM2.5) in major populated regions of China during winter 

2021 ◽  
Author(s):  
Zixuan Jia ◽  
Ruth Doherty ◽  
Carlos Ordóñez ◽  
Chaofan Li ◽  
Oliver Wild
Keyword(s):  
Particulate Matter ◽  
Relative Humidity ◽  
Large Scale ◽  
Southern China ◽  
East Asian ◽  
River Delta ◽  
Large Scale Circulation ◽  
East Asian Trough ◽  
Siberian High ◽  
Pollution Episodes

<p>With rapid economic growth and urbanization, air pollution episodes with high levels of particulate matter (PM<sub>2.5</sub>) have become common in China. While emissions of pollutant precursors are important, meteorology also plays a major role in pollution episodes, especially in winter. We examine the influence of the dominant large-scale circulation and the key regional meteorological features on PM<sub>2.5</sub> over three major regions of China: Beijing–Tianjin–Hebei (BTH), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD). The East Asian winter monsoon (EAWM) is primarily studied, including some of its main large-scale components such as the East Asian trough and the Siberian high, as it influences PM<sub>2.5 </sub>differently in different parts of China. In the BTH region, the shallow East Asian trough curbs the invasion of northerly cold and dry air from the Siberian high which induces high relative humidity and heavy pollution, possibly via relative humidity-promoted aerosol formation and growth. A weak southerly wind in Eastern and Southern China associated with a weakened Siberian high suppresses horizontal dispersion, contributing to pollution accumulation over YRD. In addition, the El Niño-Southern Oscillation (ENSO) as the dominant mode of global ocean-atmosphere interaction has a substantial modulation on precipitation over southern China. In the PRD, weak southerly winds and precipitation deficits over southern China are conducive to atmospheric pollution possibly via reduced wet deposition. Furthermore, we construct new circulation-based indices based on the dominant large-scale circulation: a 500 hPa geopotential height-based index for BTH, a sea level pressure-based index for YRD and an 850 hPa meridional wind-based index for PRD. These three indices can effectively distinguish different levels of pollution over BTH, YRD and PRD, respectively. We also show how additional regional meteorological variables can improve the prediction of regional PM<sub>2.5</sub> concentrations for these three regions. These results are beneficial to understanding and forecasting the occurrence of severely polluted days for BTH, YRD and PRD from a large-scale perspective.</p>

scholarly journals The impact of large-scale circulation on daily fine particulate matter (PM<sub>2.5</sub>) over major populated regions of China in winter

2021 ◽  
Author(s):  
Zixuan Jia ◽  
Ruth Doherty ◽  
Carlos Ordóñez ◽  
Chaofan Li ◽  
Oliver Wild ◽  
...  
Keyword(s):  
Air Pollution ◽  
Large Scale ◽  
Southern China ◽  
Regional Scale ◽  
Meridional Wind ◽  
River Delta ◽  
Large Scale Circulation ◽  
Siberian High ◽  
Pollution Levels ◽  
The Impact

Abstract. The influence of large-scale circulation on daily PM2.5 variability through its direct effect on key regional meteorological variables is examined over three major populated regions of China: Beijing–Tianjin–Hebei (BTH), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD). In BTH, a shallow East Asian trough curbs northerly cold and dry air from the Siberian High, enhancing PM2.5 pollution levels. Weak southerly winds in eastern and southern China, associated with a weakened Siberian High, suppress horizontal dispersion, contributing to air pollution accumulation over YRD. In PRD, weak southerly winds and precipitation deficits over southern China are conducive to high PM2.5 pollution levels. To account for these dominant large-scale circulation – PM2.5 relationships, we propose three new circulation-based indices for predicting different levels of air pollution based on regional PM2.5 concentrations in each region: a 500 hPa geopotential height-based index for BTH, a sea level pressure-based index for YRD and an 850 hPa meridional wind-based index for PRD. These three indices can effectively distinguish clean days from heavily polluted days in these regions, assuming variation is solely due to meteorology. We also find that including the most important regional meteorological variable in each region improves the performance of the circulation-based indices in predicting daily PM2.5 concentrations on the regional scale. These results are beneficial to understanding and forecasting the occurrence of heavily polluted PM2.5 days in BTH, YRD and PRD from a large-scale perspective.

scholarly journals A new indicator on the impact of large-scale circulation on wintertime particulate matter pollution over China

2015 ◽  
Vol 15 (20) ◽  
pp. 11919-11929 ◽  
Author(s):  
B. Jia ◽  
Y. Wang ◽  
Y. Yao ◽  
Y. Xie
Keyword(s):  
Particulate Matter ◽  
Large Scale ◽  
Lower Troposphere ◽  
Circulation Pattern ◽  
Large Scale Circulation ◽  
High Position ◽  
Siberian High ◽  
Modis Aod ◽  
Longitudinal Position ◽  
The Impact

Abstract. Extreme particulate matter (PM) air pollution of January 2013 in China was found to be associated with an anomalous eastward extension of the Siberian High (SH). We developed a Siberian High position index (SHPI), which depicts the mean longitudinal position of the SH, as a new indicator of the large-scale circulation pattern that controls wintertime air quality in China. This SHPI explains 58 % (correlation coefficient of 0.76) of the interannual variability of wintertime aerosol optical depth (AOD) retrieved by MODIS over North China (NC) during 2001–2013. By contrast, the intensity-based conventional Siberian High index (SHI) shows essentially no skill in predicting this AOD variability. On the monthly scale, some high-AOD months for NC are accompanied with extremely high SHPIs; notably, extreme PM pollution of January 2013 can be explained by the SHPI value exceeding 2.6 times the standard deviation of the 2001–2013 January mean. When the SH extends eastward, thus higher SHPI, prevailing northwesterly winds over NC are suppressed not only in the lower troposphere but also in the middle troposphere, leading to reduced southward transport of pollution from NC to South China (SC). The SHPI hence exhibits a significantly negative correlation of −0.82 with MODIS AOD over SC during 2001–2013, although the robustness of this correlation depends on that of satellite-derived AOD. The suppressed northwesterly winds during high-SHPI winters also lead to increased relative humidity (RH) over NC. Both the wind and RH changes are responsible for enhanced PM pollution over NC during the high-SHPI winters.

scholarly journals Recent Winter Precipitation Changes over Eastern China in Different Warming Periods and the Associated East Asian Jets and Oceanic Conditions

2017 ◽  
Vol 30 (12) ◽  
pp. 4443-4462 ◽  
Author(s):  
Danqing Huang ◽  
Aiguo Dai ◽  
Jian Zhu ◽  
Yaocun Zhang ◽  
Xueyuan Kuang
Keyword(s):  
East Asia ◽  
Southern China ◽  
East Asian ◽  
Eastern China ◽  
Winter Precipitation ◽  
Northeastern China ◽  
Boreal Winter ◽  
The South ◽  
East Asian Trough ◽  
Siberian High

Global-mean surface temperature has experienced fast warming during 1985–98 but stabilized during 1999–2013, especially in boreal winter. Climate changes over East Asia between the two warming periods and the associated mechanisms have not been fully understood. Analyses of observation and reanalysis data show that winter precipitation has decreased (increased) over southern (northeastern) China from 1985–98 to 1999–2013. Winds at 300 hPa over East Asia strengthened during 1999–2013 around 30°–47.5°N but weakened to the north and south of it. This change pattern caused the East Asian polar front jet (EAPJ) and the East Asian subtropical jet (EASJ) to shift, respectively, equatorward and poleward during 1999–2013. Associated with these jet displacements, the Siberian high enhanced and the East Asian trough shifted westward. The enhanced Siberian high strengthened the East Asian winter monsoon and weakened southwesterly winds over the South China Sea, leading to precipitation decreases over southern China. The westward shift of the East Asian trough enhanced convergence and precipitation over northeastern China. A combination of a negative phase of the interdecadal Pacific oscillation and a positive phase of the Atlantic multidecadal oscillation during 1999–2013 resulted in significant tropospheric warming over the low and high latitudes and cooling over the midlatitudes of East Asia. These changes enhanced the meridional temperature gradient and thus westerlies over the region between the two jets but weakened them to the south and north of it, thereby contributing to the wind change patterns and the jet displacements.

scholarly journals A new indictor on the impact of large-scale circulation on wintertime particulate matter pollution over China

2015 ◽  
Vol 15 (13) ◽  
pp. 19275-19304 ◽  
Author(s):  
B. Jia ◽  
Y. Wang ◽  
Y. Yao ◽  
Y. Xie
Keyword(s):  
Particulate Matter ◽  
Large Scale ◽  
North China ◽  
Lower Troposphere ◽  
Circulation Pattern ◽  
Large Scale Circulation ◽  
High Position ◽  
Siberian High ◽  
Modis Aod ◽  
The Impact

Abstract. Extreme particulate matter (PM) air pollution of January 2013 in China was found to be associated with anomalous large-scale circulation patterns characterized by an eastward extension of the Siberian High (SH). We developed a Siberian High position index (SHPI), which depicts the mean longitudinal position of SH, as a new indicator of the large-scale circulation pattern that controls wintertime air quality in China. This SHPI explains 58 % (correlation coefficient of 0.76) of the interannual variability of wintertime aerosol optical depth (AOD) derived by MODIS over north China (NC) during 2000–2013, whereas the intensity-based conventional Siberian High Index (SHI) shows essentially no skill in predicting the AOD variability. On the monthly scale, some high-AOD months for NC are accompanied with extremely high SHPIs; notably, extreme PM pollution of January 2013 can be explained by the SHPI value exceeding 2.6 standard deviation of the 2000–2013 mean. When the SH extends eastward, thus higher SHPI, prevailing northwesterly winds over NC are suppressed not only in the lower troposphere but also in the middle troposphere, leading to reduced southward transport of pollution from NC to south China (SC). As a consequence, the SHPI exhibits a significantly negative correlation of −0.82 with MODIS AOD over SC during 2000–2013, although the robustness of this correlation depends on that of satellite-derived AOD. The suppressed northwesterly winds during high-SHPI winters also lead to increased relative humidity (RH) over NC. Both the wind and RH changes are responsible for enhanced PM pollution over north China during the high-SHPI winters.

scholarly journals OMI measured increasing SO<sub>2</sub> emissions due to energy industry expansion and relocation in Northwestern China

2017 ◽  
Author(s):  
Zaili Ling ◽  
Tao Huang ◽  
Yuan Zhao ◽  
Jixiang Li ◽  
Xiaodong Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Southern China ◽  
Eastern China ◽  
Step Change ◽  
River Delta ◽  
Northwestern China ◽  
Energy Industry ◽  
National Strategy ◽  
So2 Emissions ◽  
Mk Test

Abstract. The rapid economy growth makes China the largest energy consumer and sulphur dioxide (SO2) emitter in the world. In this study, we estimated the trends and step changes in the planetary boundary layer (PBL) vertical column density (VCD) of SO2 from 2005 to 2015 over China measured by the Ozone Monitoring Instrument (OMI). We show that these trends and step change years coincide with the effective date and period of the national strategy for energy development and relocation in northwestern China and the regulations in the reduction of SO2 emissions. Under the national regulations in the reduction SO2 emissions in eastern and southern China, SO2 VCD in the Pearl River Delta (PRD) of southern China exhibited the largest decline during 2005–2015 at a rate of −7 % yr-1, followed by the North China Plain (NCP) (−6.7 % yr-1), Sichuan Basin (−6.3 % yr-1), and Yangtze River Delta (YRD) (−6 % yr-1), respectively. The Mann–Kendall (MK) test reveals the step change points of declining SO2 VCD in 2009 for the PRD and 2012–2013 for eastern China responding to the implementation of SO2 control regulation in these regions. In contrast, the MK test and regression analysis also revealed increasing trends of SO2 VCD in northwestern China, particularly for several "hot spots" featured by growing SO2 VCD in those large-scale energy industry parks in northwestern China. The enhanced SO2 VCD is potentially attributable to increasing SO2 emissions due to the development of large-scale energy industry bases in energy-abundant northwestern China under the national strategy for the energy safety of China in the 21st century. We show that these large-scale energy industry bases could overwhelm the trends and changes in provincial total SO2 emissions in northwestern China and contributed increasingly to the national total SO2 emission in China. Given that northwestern China is more ecologically fragile and uniquely susceptible to atmospheric pollution as compared with the rest of China, increasing SO2 emissions in this part of China should not be overlooked and merit scientific research.

scholarly journals Changes in the Relationship between Particulate Matter and Surface Temperature in Seoul from 2002–2017

Atmosphere ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 238 ◽  
Author(s):  
Minjoong J. Kim
Keyword(s):  
Particulate Matter ◽  
Surface Temperature ◽  
Large Scale ◽  
Correlation Coefficients ◽  
Recent Decade ◽  
Pm10 Concentration ◽  
Strong Positive Correlation ◽  
Siberian High ◽  
The Relationship ◽  
Over Time

This study focuses on the changes over time in the relationship between surface temperature and particulate matter (PM) concentration over Seoul using long-term observational data. Correlation coefficients between the daily mean PM10 concentration and surface temperature were calculated to investigate the relationship between the two. The PM10 and temperature displayed a strong positive correlation, suggesting the increase in PM was driven by large-scale synoptic patterns accompanying such high temperatures. It was found that the correlation coefficient in 2002–2009 was significantly higher than that of 2010–2017, indicating that the relationship between PM10 concentration and temperature has weakened over time in recent decades. Correlation coefficients between daily averaged temperature and the PM10 of each year were calculated to account for the decreased correlation in the most recent decade. We found that the correlation coefficients between surface temperature and PM of each year exhibited a clear negative correlation with the longitudinal position of the Siberian High, suggesting that the position of the Siberian High might affect the strength of the relationship between PM concentration and temperature over Seoul. We also found that the eastward shift of the Siberian High reduces the standard deviation of pressure over Seoul, indicating reduction of synoptic perturbation. These results imply that the eastward shift of the Siberian High in recent decades might weaken the relationship between the PM and surface temperature over Seoul. This study suggests that the relationship between PM and meteorological variables is changing over time through changes in large climate variability.

scholarly journals Synoptic meteorological modes of variability for fine particulate matter (PM<sub>2.5</sub>) air quality in major metropolitan regions of China

2018 ◽  
Vol 18 (9) ◽  
pp. 6733-6748 ◽  
Author(s):  
Danny M. Leung ◽  
Amos P. K. Tai ◽  
Loretta J. Mickley ◽  
Jonathan M. Moch ◽  
Aaron van Donkelaar ◽  
...  
Keyword(s):  
Climate Change ◽  
Relative Humidity ◽  
Negative Correlation ◽  
Southern China ◽  
Central China ◽  
Meteorological Variables ◽  
Strong Correlations ◽  
Siberian High ◽  
Synoptic Weather ◽  
Bth Region

Abstract. In his study, we use a combination of multivariate statistical methods to understand the relationships of PM2.5 with local meteorology and synoptic weather patterns in different regions of China across various timescales. Using June 2014 to May 2017 daily total PM2.5 observations from ∼ 1500 monitors, all deseasonalized and detrended to focus on synoptic-scale variations, we find strong correlations of daily PM2.5 with all selected meteorological variables (e.g., positive correlation with temperature but negative correlation with sea-level pressure throughout China; positive and negative correlation with relative humidity in northern and southern China, respectively). The spatial patterns suggest that the apparent correlations with individual meteorological variables may arise from common association with synoptic systems. Based on a principal component analysis of 1998–2017 meteorological data to diagnose distinct meteorological modes that dominate synoptic weather in four major regions of China, we find strong correlations of PM2.5 with several synoptic modes that explain 10 to 40 % of daily PM2.5 variability. These modes include monsoonal flows and cold frontal passages in northern and central China associated with the Siberian High, onshore flows in eastern China, and frontal rainstorms in southern China. Using the Beijing–Tianjin–Hebei (BTH) region as a case study, we further find strong interannual correlations of regionally averaged satellite-derived annual mean PM2.5 with annual mean relative humidity (RH; positive) and springtime fluctuation frequency of the Siberian High (negative). We apply the resulting PM2.5-to-climate sensitivities to the Intergovernmental Panel on Climate Change (IPCC) Coupled Model Intercomparison Project Phase 5 (CMIP5) climate projections to predict future PM2.5 by the 2050s due to climate change, and find a modest decrease of ∼ 0.5 µg m−3 in annual mean PM2.5 in the BTH region due to more frequent cold frontal ventilation under the RCP8.5 future, representing a small “climate benefit”, but the RH-induced PM2.5 change is inconclusive due to the large inter-model differences in RH projections.

scholarly journals Processes for Occurrence of Strong Cold Events over Eastern China

2017 ◽  
Vol 30 (22) ◽  
pp. 9247-9266 ◽  
Author(s):  
Lei Song ◽  
Renguang Wu
Keyword(s):  
North Atlantic ◽  
High Latitude ◽  
Wave Train ◽  
East Asian ◽  
Eastern China ◽  
Cold Air ◽  
East Asian Trough ◽  
Siberian High ◽  
Cold Events ◽  
Upper Level

A strong cold event hit eastern China around 24 January 2016 with surface air temperature reaching more than 10°C below the climatological mean in most regions of eastern China south of 40°N. A total of 37 strong cold events similar to the January 2016 event with temperature anomalies over eastern China exceeding −5°C have been identified during the winters from 1979/80 to 2015/16. A comparative analysis of events with surface temperature anomalies of the same intensity but limited to north of 40°N indicates that the southward invasion of cold air to eastern China south of 40°N is related to two factors. One is the latitudinal location of the upper-level wave train, the surface Siberian high, and the midtropospheric East Asian trough over the mid- to high-latitude Eurasian continent. The other is a subtropical upper-level wave train emanating from the midlatitude North Atlantic. The emergence of the subtropical wave train is related to the positive phase of the North Atlantic Oscillation (NAO). When the mid- to high-latitude wave train is located too far northward and the subtropical wave train induces an anomalous midtropospheric high over southern China, the East Asian trough does not extend southwestward and the Siberian high does not expand southeastward. In such a case, the cold air mainly affects northeastern China and northern Japan.

scholarly journals OMI-measured increasing SO<sub>2</sub> emissions due to energy industry expansion and relocation in northwestern China

2017 ◽  
Vol 17 (14) ◽  
pp. 9115-9131 ◽  
Author(s):  
Zaili Ling ◽  
Tao Huang ◽  
Yuan Zhao ◽  
Jixiang Li ◽  
Xiaodong Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Southern China ◽  
Eastern China ◽  
Step Change ◽  
River Delta ◽  
Northwestern China ◽  
Energy Industry ◽  
National Strategy ◽  
So2 Emissions ◽  
Mk Test

Abstract. The rapid growth of economy makes China the largest energy consumer and sulfur dioxide (SO2) emitter in the world. In this study, we estimated the trends and step changes in the planetary boundary layer (PBL) vertical column density (VCD) of SO2 from 2005 to 2015 over China measured by the Ozone Monitoring Instrument (OMI). We show that these trends and step change years coincide with the effective date and period of the national strategy for energy development and relocation in northwestern China and the regulations in the reduction of SO2 emissions. Under the national regulations for the reduction of SO2 emissions in eastern and southern China, SO2 VCD in the Pearl River Delta (PRD) of southern China exhibited the largest decline during 2005–2015 at a rate of −7 % yr−1, followed by the North China Plain (NCP) (−6.7 % yr−1), Sichuan Basin (−6.3 % yr−1), and Yangtze River Delta (YRD) (−6 % yr−1). The Mann–Kendall (MK) test reveals the step change points of declining SO2 VCD in 2009 for the PRD and 2012–2013 for eastern China responding to the implementation of SO2 control regulation in these regions. In contrast, the MK test and regression analysis also revealed increasing trends of SO2 VCD in northwestern China, particularly for several hot spots featured by growing SO2 VCD in those large-scale energy industry bases in northwestern China. The enhanced SO2 VCD is potentially attributable to increasing SO2 emissions due to the development of large-scale energy industry bases in energy-abundant northwestern China under the national strategy for the energy safety of China in the 21st century. We show that these large-scale energy industry bases could overwhelm the trends and changes in provincial total SO2 emissions in northwestern China and contribute increasingly to the national total SO2 emissions in China. Given that northwestern China is more ecologically fragile and uniquely susceptible to atmospheric pollution than the rest of China, increasing SO2 emissions in this part of China should not be overlooked and merit scientific research.

scholarly journals Interannual and Interdecadal Variability of the Number of Cold Days in Hong Kong and Their Relationship with Large-Scale Circulation

2015 ◽  
Vol 143 (4) ◽  
pp. 1438-1454 ◽  
Author(s):  
Hoffman H. N. Cheung ◽  
Wen Zhou ◽  
Sai-ming Lee ◽  
Hang-wai Tong
Keyword(s):  
Hong Kong ◽  
Large Scale ◽  
Polar Region ◽  
East Asian Winter Monsoon ◽  
Southern China ◽  
Winter Monsoon ◽  
Large Scale Circulation ◽  
Meridional Gradient ◽  
Asian Winter Monsoon ◽  
The Past

Abstract During the past decade (2004/05–2013/14), the number of cold days in Hong Kong (NCD), as a proxy of the temperature of southern China, appeared to have increased from the historical minimum, in contrast to a remarkable decline in the entire postwar period. This is related to the recent apparent changes in the large-scale circulation upstream and downstream of the East Asian winter monsoon (EAWM) region: the increase in Ural blocking (UB) that enhances cold advection from the polar region and reinforces the Siberian high and the decrease in a western Pacific (WP)-like index that corresponds to increasing meridional gradient of geopotential height over the EAWM region. Overall, UB and WP account for 26.4% of the interannual (≤8 yr) variance and 83.7% of the decadal (&gt;8 yr) variance of NCD for the period 1948/49–2013/14, indicating that further study could lead to improvement in the prediction of NCD.

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