title: Spatial variance and assessment of nitrogen dioxide pollution in major cities of Pakistan along N5-Highway.
abstract: This paper discusses the findings of the first car MAX-DOAS (multi-axis differential optical absorption spectroscopy) field campaign (300km long) along the National Highway-05 (N5-Highway) of Pakistan conducted on 13 and 14 November, 2012. The main objective of the field campaign was to assess the spatial distribution of tropospheric nitrogen dioxide (NO2) columns and corresponding concentrations along the N5-Highway from Islamabad to Lahore. Source identification of NO2 revealed that the concentrations were higher within major cities along the highway. The highest NO2 vertical column densities (NO2 VCDs) were found around two major cities of Rawalpindi and Lahore. This study also presents a comparison of NO2 VCDs measured by the ozone monitoring instrument (OMI) and car MAX-DOAS observations. The comparison revealed similar spatial distribution of the NO2 columns with both car MAX-DOAS and satellite observations, but the car MAX-DOAS observations show much more spatial details. Maximum NO2 VCD retrieved from car MAX-DOAS observations was up to an order of magnitude larger than the OMI observations in urban areas.
authors.affiliation: Institute of Environmental Sciences and Engineering (IESE), National University of Sciences and Technology (NUST), Islamabad, Pakistan. Electronic address: yasir.shabbir1706@googlemail.com.
authors.forename: Yasir
authors.initials: Y
authors.lastname: Shabbir
authors.affiliation: Institute of Environmental Sciences and Engineering (IESE), National University of Sciences and Technology (NUST), Islamabad, Pakistan. Electronic address: fahim.khokhar@iese.nust.edu.pk.
authors.forename: Muhammad Fahim
authors.initials: MF
authors.lastname: Khokhar
authors.affiliation: Satellite Remote Sensing Group, Max-Planck-Institute for Chemistry, Mainz, Germany.
authors.forename: Reza
authors.initials: R
authors.lastname: Shaiganfar
authors.affiliation: Satellite Remote Sensing Group, Max-Planck-Institute for Chemistry, Mainz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wagner
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D002947:Cities / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D009585:Nitrogen Dioxide / Q000032:analysis*; D010154:Pakistan; D014186:Transportation / Q000706:statistics & numerical data
chemical_list: D000393:Air Pollutants; D009585:Nitrogen Dioxide
keywords: Car MAX-DOAS; N5-Highway; Nitrogen dioxide; Pakistan National Environmental Quality Standards; Satellite remote sensing