title: Effects of local meteorology and aerosols on ozone and nitrogen dioxide retrievals from OMI and pandora spectrometers in Maryland, USA during DISCOVER-AQ 2011.
abstract: An analysis is presented for both ground- and satellite-based retrievals of total column ozone and nitrogen dioxide levels from the Washington, D.C., and Baltimore, Maryland, metropolitan area during the NASA-sponsored July 2011 campaign ofDerivingInformation onSurfaceCOnditions from Column andVERtically Resolved Observations Relevant toAirQuality (DISCOVER-AQ). Satellite retrievals of total column ozone and nitrogen dioxide from the Ozone Monitoring Instrument (OMI) on the Aura satellite are used, while Pandora spectrometers provide total column ozone and nitrogen dioxide amounts from the ground. We found that OMI and Pandora agree well (residuals within ±25 % for nitrogen dioxide, and ±4.5 % for ozone) for a majority of coincident observations during July 2011. Comparisons with surface nitrogen dioxide from a Teledyne API 200 EU NOxAnalyzer showed nitrogen dioxide diurnal variability that was consistent with measurements by Pandora. However, the wide OMI field of view, clouds, and aerosols affected retrievals on certain days, resulting in differences between Pandora and OMI of up to ±65 % for total column nitrogen dioxide, and ±23 % for total column ozone. As expected, significant cloud cover (cloud fraction >0.2) was the most important parameter affecting comparisons of ozone retrievals; however, small, passing cumulus clouds that do not coincide with a high (>0.2) cloud fraction, or low aerosol layers which cause significant backscatter near the ground affected the comparisons of total column nitrogen dioxide retrievals. Our results will impact post-processing satellite retrieval algorithms and quality control procedures.
authors.affiliation: Department of Meteorology, The Pennsylvania State University, University Park, PA USA.
authors.forename: Andra J
authors.initials: AJ
authors.lastname: Reed
authors.affiliation: Department of Meteorology, The Pennsylvania State University, University Park, PA USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Thompson
authors.affiliation: Department of Meteorology, The Pennsylvania State University, University Park, PA USA.
authors.forename: Debra E
authors.initials: DE
authors.lastname: Kollonige
authors.affiliation: Department of Meteorology, The Pennsylvania State University, University Park, PA USA.
authors.forename: Douglas K
authors.initials: DK
authors.lastname: Martins
authors.affiliation: Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD USA ; NASA Goddard Space Flight Center, Greenbelt, MD USA.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Tzortziou
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD USA ; Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD USA.
authors.forename: Jay R
authors.initials: JR
authors.lastname: Herman
authors.affiliation: Goddard Earth Sciences and Technology Center, University of Maryland, Baltimore County, Baltimore, MD USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Berkoff
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD USA ; LuftBlick, Kreith, Austria.
authors.forename: Nader K
authors.initials: NK
authors.lastname: Abuhassan
authors.affiliation: NASA Goddard Space Flight Center, Greenbelt, MD USA ; School of Engineering, Morgan State University, Baltimore, MD USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Cede
keywords: Atmospheric chemistry; DISCOVER-AQ; Ozone Monitoring Instrument (OMI); Pandora; Total column nitrogen dioxide; Total column ozone