06 Jan 2021

06 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal ACP.

Comprehensive evaluations of diurnal NO2 measurements during DISCOVER-AQ 2011: Effects of resolution dependent representation of NOx emissions

Jianfeng Li1,a, Yuhang Wang1, Ruixiong Zhang1, Charles Smeltzer1, Andrew Weinheimer2, Jay Herman3, K. Folkert Boersma4,5, Edward A. Celarier6,7,b, Russell W. Long8, James J. Szykman8, Ruben Delgado3, Anne M. Thompson6, Travis N. Knepp9,10, Lok N. Lamsal6, Scott J. Janz6, Matthew G. Kowalewski6, Xiong Liu11, and Caroline R. Nowlan11 Jianfeng Li et al.
  • 1School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
  • 2National Center for Atmospheric Research, Boulder, Colorado, USA
  • 3University of Maryland Baltimore County JCET, Baltimore, Maryland, USA
  • 4Royal Netherlands Meteorological Institute, De Bilt, the Netherlands
  • 5Wageningen University, Meteorology and Air Quality Group, Wageningen, the Netherlands
  • 6NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 7Universities Space Research Association, Columbia, Maryland, USA
  • 8National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
  • 9NASA Langley Research Center, Virginia, USA
  • 10Science Systems and Applications, Inc., Hampton, Virginia, USA
  • 11Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
  • anow at: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington, USA
  • bnow at: Digital Spec, Tyson's Corner, VA, USA

Abstract. Nitrogen oxides (NOx = NO + NO2) play a crucial role in the formation of ozone and secondary inorganic and organic aerosols, thus affecting human health, global radiation budget, and climate. The diurnal and spatial variations of NO2 are functions of emissions, advection, deposition, vertical mixing, and chemistry. Their observations, therefore, provide useful constraints in our understanding of these factors. We employ a Regional chEmical and trAnsport model (REAM) to analyze the observed temporal (diurnal cycles) and spatial distributions of NO2 concentrations and tropospheric vertical column densities (TVCDs) using aircraft in situ measurements, surface EPA Air Quality System (AQS) observations, as well as the measurements of TVCDs by satellite instruments (OMI: the Ozone Monitoring Instrument; and GOME-2A: Global Ozone Monitoring Experiment – 2A), ground-based Pandora, and the Airborne Compact Atmospheric Mapper (ACAM) instrument, in July 2011 during the DISCOVER-AQ campaign over the Baltimore-Washington region. The model simulations at 36- and 4-km resolutions are in reasonably good agreement with the temporospatial NO2 observations in the daytime. However, nighttime mixing in the model needs to be enhanced to reproduce the observed NO2 diurnal cycle in the model. Another discrepancy is that Pandora measured NO2 TVCDs show much less variation in the late afternoon than simulated in the model. Relative to the 36-km model simulations, the 4-km model results show larger biases compared to the observations due largely to the larger spatial variations of NO2 in the model when the spatial resolution is increased from 36 to 4 km, although the biases are often comparable to the ranges of the observations. The high-resolution aircraft ACAM observations show a more dispersed distribution of NO2 vertical column densities (VCDs) and lower VCDs in urban regions than 4-km model simulations, reflecting likely the spatial distribution bias of NOx emissions in the National Emissions Inventory (NEI) 2011 at high resolution.

Jianfeng Li et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1193', Anonymous Referee #1, 12 Feb 2021
    • AC1: 'Reply on RC1', Jianfeng Li, 13 Apr 2021
  • RC2: 'Comment on acp-2020-1193', Anonymous Referee #2, 15 Feb 2021
    • AC2: 'Reply on RC2', Jianfeng Li, 13 Apr 2021

Jianfeng Li et al.

Jianfeng Li et al.


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Latest update: 15 Apr 2021
Short summary
Comprehensive evaluations of simulated diurnal cycles of NO2 and NOy concentrations, vertical profiles, and tropospheric vertical column densities at two different resolutions with various measurements during the DISCOVER-AQ 2011 campaign show the reasonability of the National Emission Inventory 2011 NOx emissions at coarser resolutions but potential distribution biases at 4-km resolution, providing another possible explanation for the overestimation of model results at high resolutions.