Spatial and temporal variations of tropospheric formaldehyde (HCHO) column concentrations over Egypt during 1997-2021 based on multi-satellites observations is presented. The HCHO growth rates are analyzed and the influencing factors of HCHO such as, vegetation presented by the NDVI (normalized difference vegetation index), meteorology and backward trajectories for qualitatively exploring the impacts of natural and anthropogenic emissions on HCHO variations are also addressed. The main results are: the annual average HCHO column concentrations in the Egyptian region is 3.71×1015~ 9×1015molec/cm2, and the highest values are mainly concentrated in the Nile Delta, immediately followed by in the North Mediterranean coast, Sinai Peninsula, and the eastern coastal areas, while the lowest values are found in the desert areas of the south-west. The annual HCHO concentrations showed an overall increasing trend from 1997 to 2021, with highest (lowest) values in summer (winter). Among the natural factors, the HCHO geographical gradient differences are mainly influenced by the combination of wind, vegetation and marine factors. Industrial emissions, and economic activities enhanced the HCHO growth rate be higher in the Nile Delta cities than in other cities, and the rate is strongly correlated with the increase of atmospheric methane.

Guanghui Zheng, Tianzhen Ju, Yumeng Qiu, Jiachen Li, Zhichao Lv. Atmospheric Formaldehyde Column Concentrations from Multi-Satellites Data Observations over Egypt, 1997-2021. Academic Journal of Environment & Earth Science (2025), Vol. 7, Issue 4: 9-25. https://doi.org/10.25236/AJEE.2025.070402.

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