Insight into global trends in aerosol composition from 2005 to 2015 inferred from the OMI Ultraviolet Aerosol Index

Hammer, Melanie S.; Martin, Randall V.; Li, Chi; Torres, Omar; Manning, Max; Boys, Brian L.

doi:10.5194/acp-18-8097-2018

Cited by 39 publications

(25 citation statements)

References 104 publications

(119 reference statements)

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“…The impact of anthropogenic haze and marine particles on the absorption of radiation at 354 nm is comparably low. AI typically ranges from −0.5 to 0.2 over North America and Europe in the absence of biomass burning (Hammer et al, 2018). Figure 2 shows the aerosol layering over Kosetice, Czech Republic, from 20 to 23 August 2017.…”

Section: Satellite-derived Products: Modis and Omi Retrievalsmentioning

confidence: 99%

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

et al. 2018

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Abstract. Light extinction coefficients of 500 Mm −1 , about 20 times higher than after the Pinatubo volcanic eruptions in 1991, were observed by European Aerosol Research Lidar Network (EARLINET) lidars in the stratosphere over central Europe on 21-22 August 2017. Pronounced smoke layers with a 1-2 km vertical extent were found 2-5 km above the local tropopause. Optically dense layers of Canadian wildfire smoke reached central Europe 10 days after their injection into the upper troposphere and lower stratosphere which was caused by rather strong pyrocumulonimbus activity over western Canada. The smoke-related aerosol optical thickness (AOT) identified by lidar was close to 1.0 at 532 nm over Leipzig during the noon hours on 22 August 2017. Smoke particles were found throughout the free troposphere (AOT of 0.3) and in the pronounced 2 km thick stratospheric smoke layer at an altitude of 14-16 km (AOT of 0.6). The lidar observations indicated peak mass concentrations of 70-100 µg m −3 in the stratosphere. In addition to the lidar profiles, we analyzed Moderate Resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) over Canada, and the distribution of MODIS AOT and Ozone Monitoring Instrument (OMI) aerosol index across the North Atlantic. These instruments showed a similar pattern and a clear link between the western Canadian fires and the aerosol load over Europe. In this paper, we also present Aerosol Robotic Network (AERONET) sun photometer observations, compare photometer and lidar-derived AOT, and discuss an obvious bias (the smoke AOT is too low) in the photometer observations. Finally, we compare the strength of this recordbreaking smoke event (in terms of the particle extinction coefficient and AOT) with major and moderate volcanic events observed over the northern midlatitudes.

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Section: Satellite-derived Products: Modis and Omi Retrievalsmentioning

confidence: 99%

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

et al. 2018

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“…The cooling effect of aerosols may partly counteract the warming caused by the increase in CO 2 and other greenhouse gases in the past several decades (Bernstein et al, 2007). On the other hand, by acting as cloud condensation nuclei or ice nuclei, not only can aerosols alter the microphysical and radiative properties of clouds, as well as their lifetimes (Rosenfeld et al, 2019;Andreae, 2009), but they can also change the precipitation efficiency (depending on the aerosol type; Jiang et al, 2018), modify the characteristics of the atmospheric circulation and affect the global hydrological cycle (Ramanathan et al, 2001;Ackerman et al, 2000;Hansen et al, 1997;Sarangi et al, 2018). This effect is termed the aerosol indirect effect.…”

Section: Introductionmentioning

confidence: 99%

Large contribution of meteorological factors to inter-decadal changes in regional aerosol optical depth

et al. 2019

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Abstract. Aerosol optical depth (AOD) has become a crucial metric for assessing global climate change. Although global and regional AOD trends have been studied extensively, it remains unclear what factors are driving the inter-decadal variations in regional AOD and how to quantify the relative contribution of each dominant factor. This study used a long-term (1980–2016) aerosol dataset from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) reanalysis, along with two satellite-based AOD datasets (MODIS/Terra and MISR) from 2001 to 2016, to investigate the long-term trends in global and regional aerosol loading. Statistical models based on emission factors and meteorological parameters were developed to identify the main factors driving the inter-decadal changes of regional AOD and to quantify their contribution. Evaluation of the MERRA-2 AOD with the ground-based measurements of AERONET indicated significant spatial agreement on the global scale (r= 0.85, root-mean-square error = 0.12, mean fractional error = 38.7 %, fractional gross error = 9.86 % and index of agreement = 0.94). However, when AOD observations from the China Aerosol Remote Sensing Network (CARSNET) were employed for independent verification, the results showed that MERRA-2 AODs generally underestimated CARSNET AODs in China (relative mean bias = 0.72 and fractional gross error =-34.3 %). In general, MERRA-2 was able to quantitatively reproduce the annual and seasonal AOD trends on both regional and global scales, as observed by MODIS/Terra, although some differences were found when compared to MISR. Over the 37-year period in this study, significant decreasing trends were observed over Europe and the eastern United States. In contrast, eastern China and southern Asia showed AOD increases, but the increasing trend of the former reversed sharply in the most recent decade. The statistical analyses suggested that the meteorological parameters explained a larger proportion of the AOD variability (20.4 %–72.8 %) over almost all regions of interest (ROIs) during 1980–2014 when compared with emission factors (0 %–56 %). Further analysis also showed that SO2 was the dominant emission factor, explaining 12.7 %–32.6 % of the variation in AOD over anthropogenic-aerosol-dominant regions, while black carbon or organic carbon was the leading factor over the biomass-burning-dominant (BBD) regions, contributing 24.0 %–27.7 % of the variation. Additionally, wind speed was found to be the leading meteorological parameter, explaining 11.8 %–30.3 % of the variance over the mineral-dust-dominant regions, while ambient humidity (including soil moisture and relative humidity) was the top meteorological parameter over the BBD regions, accounting for 11.7 %–35.5 % of the variation. The results of this study indicate that the variation in meteorological parameters is a key factor in determining the inter-decadal change in regional AOD.

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“…Phys. North America and Europe have declined in response to emissions control (Hammer et al, 2018). In contrast, pollutant emissions and their precursors in the rapidly developing countries (such as India and China) have increased over the past few decades, attributable to enhanced industrial activity.…”

Section: Introductionmentioning

confidence: 99%

Large contribution of meteorological factors to inter-decadal changes in regional aerosol optical depth

Che¹,

Gui²,

Xia³

et al. 2019

Preprint

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Abstract. Aerosol optical depth (AOD) has become a crucial metric for assessing global climate change. Although global and regional AOD trends have been studied extensively, it remains unclear what factors are driving the inter-decadal variations in regional AOD and how to quantify the relative contribution of each dominant factor. This study used a long-term (1980&#8211;2016) aerosol dataset from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) reanalysis, along with two satellite-based AOD datasets (MODIS/Terra and MISR) from 2001 to 2016, to investigate the long-term trends in global and regional aerosol loading. Statistical models based on emission factors and meteorological parameters were developed to identify the main factors driving the inter-decadal changes of regional AOD and to quantify their contribution. Evaluation of the MERRA-2 AOD with the combined in-situ measurements of AERONET and the China Aerosol Remote Sensing Network indicated significant spatial agreement on the global scale (r&#8201;=&#8201;0.84, RMSE&#8201;=&#8201;0.14, and MAE&#8201;=&#8201;0.07). In general, MERRA-2 was able to quantitatively reproduce the annual and seasonal AOD trends on both regional and global scales, as observed by MODIS/Terra, albeit some differences were found when compared to MISR. Over the 37-year period in this study, significant decreasing trends were observed over Europe and the eastern United States. In contrast, eastern China and South Asia showed AOD increases, but the increasing trend of the former reversed sharply in the most recent decade. The statistical analyses suggested that the meteorological parameters explained a larger proportion of the AOD variability (20.4&#8201;%&#8211;72.8&#8201;%) over almost all regions of interest (ROIs) during 1980&#8211;2014 when compared with emission factors (0&#8201;%&#8211;56&#8201;%). Further analysis also showed that SO2 was the dominant emission factor, explaining 12.7&#8201;%&#8211;32.6&#8201;% of the variation in AOD over anthropogenic aerosol&#8211;dominant regions, while BC or OC was the leading factor over the biomass burning&#8211;dominant (BBD) regions, contributing 24.0&#8201;%&#8211;27.7&#8201;% of the variation. Additionally, wind speed was found to be the leading meteorological parameter, explaining 11.8&#8201;%&#8211;30.3&#8201;% of the variance over the mineral dust&#8211;dominant regions, while ambient humidity (including soil moisture and relative humidity) was the top meteorological parameter over the BBD regions, accounting for 11.7&#8201;%&#8211;35.5&#8201;% of the variation. The results of this study indicate that the variation in meteorological parameters is a key factor in determining the inter-decadal change in regional AOD.

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Insight into global trends in aerosol composition from 2005 to 2015 inferred from the OMI Ultraviolet Aerosol Index

Cited by 39 publications

References 104 publications

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

Large contribution of meteorological factors to inter-decadal changes in regional aerosol optical depth

Large contribution of meteorological factors to inter-decadal changes in regional aerosol optical depth

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