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Volume 15, No. 5, October 2015, Pages 1760-1773 PDF(9.15 MB)  
doi: 10.4209/aaqr.2014.12.0339   

Spatio-Temporal Analyses of Formaldehyde over Pakistan by Using SCIAMACHY and GOME-2 Observations

Muhammad Fahim Khokhar1, Tameem Khalid1, Naila Yasmin1, Isabelle De Smedt2

1 Institute of Environmental Sciences and Engineering (IESE), National University of Sciences and Technology (NUST) Islamabad, Pakistan
2 Belgian Institute for Space Aeronomy (BIRA-IASB) Brussels, Belgium


  • First database of HCHO VCDs over Pakistan by using satellite observations.
  • A statistically insignificant temporal trend in HCHO columns was identified.
  • Seasonality in HCHO column is attributed to biogenic emissions and vegetation fires.
  • Extensive use of compressed natural gas also contribute to enhanced levels of HCHO.



This study primarily focuses on monitoring of tropospheric formaldehyde (HCHO) column densities over Pakistan during the time period of year 2003 to 2012. Observations from two satellite instruments SCIAMACHY (Scanning imaging absorption spectrometer for atmospheric chartography, on-board ENVISAT-1) and GOME-2 (Global ozone monitoring experiment, on-board Metop-A) were used. Spatial and temporal distributions of HCHO column densities over Pakistan are analysed. Spatial maps were generated in order to see the distribution of HCHO and to identify major hotspots across the country. Seasonal cycle of HCHO over all provinces of Pakistan showed the summer maximum attributed to increase in biogenic emissions and biomass burning activities. Further emphasis was made on source identification of HCHO emissions. It revealed that agriculture fires and extensive use of compressed natural gas (CNG) as fuel also contribute to tropospheric HCHO in Pakistan. World fire atlas data from along track scanning radiometer (ATSR) was used to identify effect of agriculture waste burning on HCHO concentration in Pakistan. Significant correlation was observed between agricultural fires and increased HCHO column densities.



Keywords: Tropospheric HCHO; SCIAMACHY; GOME-2; Biogenic emissions; Agriculture fires; Pakistan.



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