A high-resolution and observationally constrained OMI NO2 satellite retrieval

Daniel L. Goldberg, Lok N. Lamsal, Christopher P. Loughner, William H. Swartz, Zifeng Lu, David G. Streets
2017 Atmospheric Chemistry and Physics  
<p><strong>Abstract.</strong> This work presents a new high-resolution NO<sub>2</sub> dataset derived from the NASA Ozone Monitoring Instrument (OMI) NO<sub>2</sub> version 3.0 retrieval that can be used to estimate surface-level concentrations. The standard NASA product uses NO<sub>2</sub> vertical profile shape factors from a 1.25°<span class="thinspace"></span> × <span class="thinspace"></span>1° (∼ <span class="thinspace"></span>110<span class="thinspace"></span>km<span
more » ... lass="thinspace"></span> × <span class="thinspace"></span>110<span class="thinspace"></span>km) resolution Global Model Initiative (GMI) model simulation to calculate air mass factors, a critical value used to determine observed tropospheric NO<sub>2</sub> vertical columns. To better estimate vertical profile shape factors, we use a high-resolution (1.33<span class="thinspace"></span>km<span class="thinspace"></span> × <span class="thinspace"></span>1.33<span class="thinspace"></span>km) Community Multi-scale Air Quality (CMAQ) model simulation constrained by in situ aircraft observations to recalculate tropospheric air mass factors and tropospheric NO<sub>2</sub> vertical columns during summertime in the eastern US. In this new product, OMI NO<sub>2</sub> tropospheric columns increase by up to 160<span class="thinspace"></span>% in city centers and decrease by 20–50<span class="thinspace"></span>% in the rural areas outside of urban areas when compared to the operational NASA product. Our new product shows much better agreement with the Pandora NO<sub>2</sub> and Airborne Compact Atmospheric Mapper (ACAM) NO<sub>2</sub> spectrometer measurements acquired during the DISCOVER-AQ Maryland field campaign. Furthermore, the correlation between our satellite product and EPA NO<sub>2</sub> monitors in urban areas has improved dramatically: <i>r</i><sup>2</sup><span class="thinspace"></span> = <span class="thinspace"></span>0.60 in the new product vs. <i>r</i><sup>2</sup><span class="thinspace"></span> = <span class="thinspace"></span>0.39 in the operational product, signifying that this new product is a better indicator of surface concentrations than the operational product. Our work emphasizes the need to use both high-resolution and high-fidelity models in order to recalculate satellite data in areas with large spatial heterogeneities in NO<sub><i>x</i></sub> emissions. Although the current work is focused on the eastern US, the methodology developed in this work can be applied to other world regions to produce high-quality region-specific NO<sub>2</sub> satellite retrievals.</p>
doi:10.5194/acp-17-11403-2017 fatcat:m5ty3c3i2vcdtnpdakasdztkk4