Application of OMI, SCIAMACHY, and GOME‐2 satellite SO₂ retrievals for detection of large emission sources

Abstract

Retrievals of sulfur dioxide (SO2) from space‐based spectrometers are in a relatively early stage of development. Factors such as interference between ozone and SO2 in the retrieval algorithms often lead to errors in the retrieved values. Measurements from the Ozone Monitoring Instrument (OMI), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), and Global Ozone Monitoring Experiment‐2 (GOME‐2) satellite sensors, averaged over a period of several years, were used to identify locations with elevated SO2 values and estimate their emission levels. About 30 such locations, detectable by all three sensors and linked to volcanic and anthropogenic sources, were found after applying low and high spatial frequency filtration designed to reduce noise and bias and to enhance weak signals to SO2 data from each instrument. Quantitatively, the mean amount of SO2 in the vicinity of the sources, estimated from the three instruments, is in general agreement. However, its better spatial resolution makes it possible for OMI to detect smaller sources and with additional detail as compared to the other two instruments. Over some regions of China, SCIAMACHY and GOME‐2 data show mean SO2 values that are almost 1.5 times higher than those from OMI, but the suggested spatial filtration technique largely reconciles these differences.

IASI observations of sulfur dioxide (SO2) in the boundary layer of Norilsk

“…Humidity stays low for the entire winter and therefore does not contribute to the loss of sensitivity. This kind of unfavorable winter episodes occurs for instance in January There are several previous reports of SO 2 measurements in Norilsk, which were made either by surface instruments [Fukasawa et al, 2000], airplanes [Walter et al, 2012], or satellites using reflected solar radiation in the UV-visible [Walter et al, 2012;Fioletov et al, 2013]. Table 1 summarizes the different available SO 2 measurements and compares them to this work.…”

Tropospheric emissions: Monitoring of pollution (TEMPO)

“…Issues in the representation of snow-covered surfaces also lead to larger uncertainties [82]. Canadian academia and government are collaborating to address these by developing direct inversions [80] to improve sensitivity in the boundary layer [29], developing methods to better constrain stratospheric abundances including assimilation of stratospheric profiles, implementing an improved representation of snow in the inversions [74], and developing algorithms to explicitly account for the effects of aerosols on trace gas retrievals [64]. Validation of TEMPO observations over Canada is also a priority with an expansion of the Canadian Pandora network [37] and an aircraft measurement campaign being planned.…”

Evaluation of tropospheric SO<sub>2</sub> retrieved from MAX-DOAS measurements in Xianghe, China

“…So far, the SO 2 surface concentration has been monitored using in situ and long-path DOAS (differential optical absorption spectroscopy) instruments (Meng et al, 2009), while satellite sensors like GOME, SCIAMACHY, GOME-2, OMI, OMPS, and IASI have shown their ability to measure the SO 2 vertical column density (VCD) over polluted areas (see, e.g., Eisinger and Burrows, 1998;Krotkov et al, 2006;Lee et al, 2009;Nowlan et al, 2011;Fioletov et al, 2013;Yang et al, 2013;Boynard et al, 2014). During the last decade, a new remote sensing technique called MAX-DOAS (multi-axis differential optical absorption spectroscopy) has been developed, providing information on both VCD and vertical distribution of trace gases in the troposphere (Hön-ninger et al, 2004;Platt and Stutz, 2008).…”