Improvement of Air Pollution in China Inferred from Changes between Satellite-Based and Measured Surface Solar Radiation

Wang, Yawen; Trentmann, Jörg; Pfeifroth, Uwe; Yuan, Wenping; Wild, Martin

doi:10.3390/rs11242910

Cited by 11 publications

(9 citation statements)

References 66 publications

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“…These studies suggest the major role of vehicular traffic in air quality control. While government pollution control policies appear to have improved air quality in Beijing and Tianjin [5][6][7], pervasive pollution is still evident across a much larger surrounding region, as demonstrated by Yuan and Yang's [8] report of significant worsening in other cities of the BTH region.…”

Section: Introductionmentioning

confidence: 99%

Air Pollution Scenario over China during COVID-19

et al. 2020

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The unprecedented slowdown in China during the COVID-19 period of November 2019 to April 2020 should have reduced pollution in smog-laden cities. However, moderate resolution imaging spectrometer (MODIS) satellite retrievals of aerosol optical depth (AOD) show a marked increase in aerosols over the Beijing–Tianjin–Hebei (BHT) region and most of Northeast and Central China, compared with the previous winter. Fine particulate (PM2.5) data from ground monitoring stations show an increase of 19.5% in Beijing during January and February 2020, and no reduction for Tianjin. In March and April 2020, a different spatial pattern emerges, with very high AOD levels observed over 50% of the Chinese mainland, and including peripheral regions in the northwest and southwest. At the same time, ozone monitoring instrument (OMI) satellite-derived NO2 concentrations fell drastically across China. The increase in PM2.5 while NO2 decreased in BTH and across China is likely due to enhanced production of secondary particulates. These are formed when reductions in NOx result in increased ozone formation, thus increasing the oxidizing capacity of the atmosphere. Support for this explanation is provided by ground level air quality data showing increased volume of fine mode aerosols throughout February and March 2020, and increased levels of PM2.5, relative humidity (RH), and ozone during haze episodes in the COVID-19 lockdown period. Backward trajectories show the origin of air masses affecting industrial centers of North and East China to be local. Other contributors to increased atmospheric particulates may include inflated industrial production in peripheral regions to compensate loss in the main population and industrial centers, and low wind speeds. Satellite monitoring of the extraordinary atmospheric conditions resulting from the COVID-19 shutdown could enhance understanding of smog formation and attempts to control it.

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Section: Introductionmentioning

confidence: 99%

Air Pollution Scenario over China during COVID-19

et al. 2020

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“…Consistent with the global trend, a similar transition has been widely reported in the R trend of China with the estimated changing rates of −2.5 to −12 and 0.4 to 4 W m −2 decade −1 during the global dimming and brightening phases, respectively (Wang & Yang, ). Based on homogeneous data, recent studies further updated the decadal variations of R in China into three stages: a dimming until 1990, a leveling off afterward, and an actual brightening since 2008 (Wang, Trentmann et al, ; Yang et al, , ).…”

Section: Introductionmentioning

confidence: 99%

A Revisit of Direct and Diffuse Solar Radiation in China Based on Homogeneous Surface Observations: Climatology, Trends, and Their Probable Causes

et al. 2020

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Increasing energy and food demands require an understanding of not only the availability and variability of total solar radiation (R) but also its partitioning into direct (R d ) and diffuse (R f ) components, which are key elements for solar power generation and plant photosynthesis, respectively. Potential inhomogeneities in surface solar radiation observations, however, add uncertainties to the published patterns and trends of R d and R f over China. To exclude inhomogeneous time series and outliers, a data quality control process has been applied to the surface observations of R d and R f . The homogeneous data show that, in response to the global dimming and brightening phenomena in R, decadal changes can also be observed in the R d and R f trends over China with the actual transition occurring in the mid-2000s. Since the 1960s, R d dimming has mainly distributed over eastern China with intensive anthropogenic activities, with recoveries especially from 2008 onward over regions with high R d energy potential. R f , on the other hand, had further enhanced since the 1960s especially over the high R f proportion areas but has decreased in the recent decade over the northern region. The summer season shows the most significant decadal trends in R d and R f . Under clear-sky conditions, that is, ruling out cloud effects, the transitions in R d and R f trends become more remarkable, pointing to atmospheric aerosols as the main driving force. In addition, dramatic R d and R f variations are observed in the subsequent years after large volcanic eruptions. The varying R d and R f proportions are in line with recent governmental control on SO 2 emissions over China.

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“…Previous studies show that the Rs in China showed significant decline trends before the 1980s by 2 to 8 Wm −2 per decade [25][26][27][28][29][30][31][32], which did not persist into the 1990s. However, the magnitudes of variations in Rs were still controversial.…”

Section: Decadal Variationsmentioning

confidence: 92%

A New Long-Term Downward Surface Solar Radiation Dataset over China from 1958 to 2015

Hou

Zhang

et al. 2020

Sensors

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Downward surface solar radiation (Rs) plays a dominant role in determining the climate and environment on the Earth. However, the densely distributed ground observations of Rs are usually insufficient to meet the increasing demand of the climate diagnosis and analysis well, so it is essential to build a long-term accurate Rs dataset. The extremely randomized trees (ERT) algorithm was used to generate Rs using routine meteorological observations (2000–2015) from the Climate Data Center of the Chinese Meteorological Administration (CDC/CMA). The estimated Rs values were validated against ground measurements at the national scale with an overall correlation coefficient value of 0.97, a mean bias of 0.04 Wm−2, a root-mean-square-error value of 23.12 Wm−2, and a mean relative error of 9.81%. It indicates that the estimated Rs from the ERT-based model is reasonably accurate. Moreover, the ERT-based model was used to generate a new daily Rs dataset at 756 CDC/CMA stations from 1958 to 2015. The long-term variation trends of Rs at 454 stations covering 46 consecutive years (1970–2015) were also analyzed. The Rs in China showed a significant decline trend (−1.1 Wm−2 per decade) during 1970–2015. A decreasing trend (−2.8 Wm−2 per decade) in Rs during 1970–1992 was observed, followed by a recovery trend (0.23 Wm−2 per decade) during 1992–2015. The recovery trends at individual stations were found at 233 out of 454 stations during 1970–2015, which were mainly located in southern and northern China. The new Rs dataset would substantially provide basic data for the related studies in agriculture, ecology, and meteorology.

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Improvement of Air Pollution in China Inferred from Changes between Satellite-Based and Measured Surface Solar Radiation

Cited by 11 publications

References 66 publications

Air Pollution Scenario over China during COVID-19

Air Pollution Scenario over China during COVID-19

A Revisit of Direct and Diffuse Solar Radiation in China Based on Homogeneous Surface Observations: Climatology, Trends, and Their Probable Causes

A New Long-Term Downward Surface Solar Radiation Dataset over China from 1958 to 2015

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