Aura OMI observations of regional SO<sub>2</sub> and NO<sub>2</sub> pollution changes from 2005 to 2014

Abstract

Abstract. The Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite has been providing global observations of the ozone layer and key atmospheric pollutant gases, such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), since October 2004. The data products from the same instrument provide consistent spatial and temporal coverage and permit the study of anthropogenic and natural emissions on local-to-global scales. In this paper we examine changes in SO2 and NO2 over some of the world's most polluted industrialized regions during the first decade of OMI observations. In terms of regional pollution changes, we see both upward and downward trends, sometimes in opposite directions for NO2 and SO2, for the different study areas. The trends are, for the most part, associated with economic and/or technological changes in energy use, as well as regional regulatory policies. Over the eastern US, both NO2 and SO2 levels decreased dramatically from 2005 to 2014, by more than 40 and 80 %, respectively, as a result of both technological improvements and stricter regulations of emissions. OMI confirmed large reductions in SO2 over eastern Europe's largest coal power plants after installation of flue gas desulfurization devices. The North China Plain has the world's most severe SO2 pollution, but a decreasing trend has been observed since 2011, with about a 50 % reduction in 2012–2014, due to an economic slowdown and government efforts to restrain emissions from the power and industrial sectors. In contrast, India's SO2 and NO2 levels from coal power plants and smelters are growing at a fast pace, increasing by more than 100 and 50 %, respectively, from 2005 to 2014. Several SO2 hot spots observed over the Persian Gulf are probably related to oil and gas operations and indicate a possible underestimation of emissions from these sources in bottom-up emission inventories. Overall, OMI observations have proved to be very valuable in documenting rapid changes in air quality over different parts of the world during the last decade. The baseline established during the first 10 years of OMI is indispensable for the interpretation of air quality measurements from current and future satellite atmospheric composition missions.

A 15-year record (2001–2015) of the ratio of nitrate to non-sea-salt sulfate in precipitation over East Asia

“…The NO 2 column has been used to capture NO x emissions (e.g., Miyazaki et al, 2012;Mijling et al, 2013;Itahashi et al, 2014b;Han et al, 2015;Irie et al, 2016), and the SO 2 column has been used for SO 2 emissions (e.g., Lee et al, 2011;Li et al, 2010) and/or volcanic eruptions (e.g., Brenot et al, 2014). Several studies have indicated the importance of different technologies to control emissions (e.g., Li et al, 2010;Wang et al, 2015;Krotkov et al, 2016;van der A et al, 2017). For example, the ratio of Ozone Monitoring Instrument (OMI)-derived SO 2 / NO 2 was used to determine the effectiveness of the flue-gas desulfurization devices for power plants in China (Li et al, 2010;Wang et al, 2015).…”

“…NO x emissions in China have been rising steadily (Kurokawa et al, 2013;Itahashi et al, 2014b), whereas SO 2 emissions in China peaked in [2005][2006] and subsequently declined due to the introduction of flue-gas desulfurization systems in China's 11th Five-Year Plan (2006 (Kurokawa et al, 2013;Itahashi et al, 2012). Recently, it has been reported that NO x emissions in China declined after 2011-2012 (Irie et al, 2016;Xia et al, 2016;Krotkov et al, 2016;van der A et al, 2017). To determine the result of this change, we revisited and updated an analysis of precipitation data in relation to emission variation over East Asia.…”

Predicting decadal trends in cloud droplet number concentration using reanalysis and satellite data

“…This decrease in SO 2 over continents correlates well with CDNC observed over the Pacific (10°-40°N, 110°-150°E) and Atlantic (30°-45°N, 80°-65°W) (Figure 5c,d). Land domains were chosen to match the regions of SO 2 production in China and the US examined in Krotkov et al (2016). As noted in Krotkov et al (2016), the Yangtze River delta, Pearl River delta, and Sichuan Basin contribute the majority of emissions in China, while Pennsylvania and the Ohio River valley contribute strongly to North 30 American emissions.…”

“…Land domains were chosen to match the regions of SO 2 production in China and the US examined in Krotkov et al (2016). As noted in Krotkov et al (2016), the Yangtze River delta, Pearl River delta, and Sichuan Basin contribute the majority of emissions in China, while Pennsylvania and the Ohio River valley contribute strongly to North 30 American emissions. The averages over land have been selected to capture these regions and agree with previous studies .…”

Urban Emissions and Regional Air Quality in India

“…Many studies on Indian air quality rely on satellite observations as a result of these biases and limited availability of ground-based monitor data across India, including NO 2 from OMI aboard the Aura satellite [Lamsal et al, 2010;Ghude et al, 2013]. Satellite observations from OMI and other instruments have been previously used to evaluate emissions and surface concentrations [Lamsal et al, 2010;Lu and Streets, 2012;Lu et al, 2013;Streets et al, 2013], observe trends in air quality [Lamsal et al, 2013[Lamsal et al, , 2015Duncan et al, 2015;Krotkov et al, 2015], evaluate AOD for dust or anthropogenic pollution [King et al, 2003;Isakov et al, 2007;Zhao et al, 2010], and estimate NO X to VOC ratios in assessing O 3 regimes [Jin and Holloway, 2015]. Limitations of satellite observations include temporal availability (i.e.…”