Characterization of OMI Tropospheric NO2 Measurements in East Asia Based on a Robust Validation Comparison

Abstract

In the period from June 2006 to December 2008, we measured the tropospheric nitrogen dioxide (NO2 ) column by ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) at an urban site in China (Tai'an) and three sites in Japan, covering urban (Yokosuka), suburban (Tsukuba), and remote areas (Hedo). This robust dataset is used to characterize Ozone Monitoring Instrument (OMI) tropospheric NO2 column data (the standard product, version 3). Correlations between MAX-DOAS and OMI data, both of which show very low NO2 at Hedo and moderate/high levels at the other sites, have correlation coefficients (R 2 ) as high as 0.64, indicating that relative changes in OMI NO2 data are reliable. However, OMI data have a negative bias of 31% on average. Assuming that these results are valid for OMI data taken over China, we find an increasing trend in tropospheric column NO2 at about 5% per year on average in the industrial areas of China (30° 40°N and 110° 123°E) over 2005 2008, but its spatial distribution is highly inhomogeneous.

Quantitative bias estimates for tropospheric NO<sub>2</sub> columns retrieved from SCIAMACHY, OMI, and GOME-2 using a common standard for East Asia

“…1, the MAX-DOAS measurements were conducted at various levels of NO 2 pollution, covering urban (Yokosuka), suburban (Tsukuba) around Tokyo, and remote areas (Hedo) in Japan and the northernmost (Mangshan), middle (Tai'an), and southernmost (Rudong) parts of the highly polluted area in China. This set of observations extends the data set used by Irie et al (2009) Table 1). The instrumentation and retrieval algorithm used for all the sites have been described in detail elsewhere (e.g., Irie et al, 2008Irie et al, , 2009Irie et al, , 2011Takashima et al, , 2012.…”

“…This set of observations extends the data set used by Irie et al (2009) Table 1). The instrumentation and retrieval algorithm used for all the sites have been described in detail elsewhere (e.g., Irie et al, 2008Irie et al, , 2009Irie et al, , 2011Takashima et al, , 2012. The retrieval utilizes absorption features by NO 2 and the oxygen dimer (O 4 ) at 460-490 nm.…”

“…There have been, however, few studies attempting to quantify the biases in SCIAMACHY, OMI, and GOME-2 data in a consistent manner based on comparisons with independent observations. In East Asia, validation comparisons for specific satellite data sets are very limited, except for the NASA OMI standard product (Irie et al, 2009). Here we present a consistent data set based on Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations performed at several sites in Japan and China from 2006-2011.…”

Turnaround of Tropospheric Nitrogen Dioxide Pollution Trends in China, Japan, and South Korea

“…In this study, a long-term data quality check for OMI data over Japan was performed through long-term validation comparisons between tropospheric NO 2 VCDs derived from OMI and groundbased Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) remote sensing observations at Tsukuba, Japan (36.1°N, 140.1°E) (Irie et al 2008(Irie et al , 2009(Irie et al , 2012. The operating period of MAX-DOAS (2006 well covers the long-term OMI observations.…”

NO<sub>2</sub> observations over the western Pacific and Indian Ocean by MAX-DOAS on <i>Kaiyo</i>, a Japanese research vessel

“…Irie et al, 2009Irie et al, , 2011Takashima et al, 2009Takashima et al, , 2011. The instrument has been validated with other instruments, yielding differences of less than ∼ 10 % for NO 2 and oxygen dimer (O 4 ) differential slant column densities (DSCDs) (Roscoe et al, 2010).…”