• Sneha Dhankar
• Akash Ajay
• Gayatri Singh

From January 2010 to December 2014, an examination was carried out using data from the OMI sensor on the Aura satellite, with a spatial resolution of 0.25°x0.25°, to analyze the levels of formaldehyde (HCHO) and nitrogen dioxide (NO2) in Delhi and the surrounding region. The temporal patterns revealed that formaldehyde concentrations reached their peak during the monsoon period and reached their lowest point during the winter months. Conversely, nitrogen dioxide concentrations were minimal during the monsoon months and highest during the season of winter. The time sequence plots and scatter plot depicting the relationship between HCHO and NO2 levels indicated a significant inverse correlation between the two pollutants. The wind rose plots representing the seasons showed a prevailing west-to-east wind direction, which can be attributed to the subtropical westerlies. Additionally, the temporal plot of wind speeds indicated maximum speeds during summer, followed by monsoon, winter, and the lowest speeds in the months of post-monsoon. Spatial maps generated using ArcGIS showcased the distribution of formaldehyde and nitrogen dioxide in the study area, highlighting specific hot spots. Notably, the eastern part of Delhi exhibited higher concentrations of nitrogen dioxide compared to other regions. However, identifying hot spots for formaldehyde proved challenging as they varied with the seasons, likely due to the intricate chemistry of formaldehyde in the troposphere. The observed variations were tentatively explained by considering the atmospheric chemistry of nitrogen dioxide and formaldehyde, emphasizing the presence of highly complex interactions between these pollutants.

Formaldehyde, Nitrogen dioxide, Spatial maps, Hotspots.

"Temporal and Spatial Patterns of Nitrogen dioxide (NO2) and Formaldehyde (HCHO) in Delhi and Surrounding Regions: Analysis Using Satellite Data", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 1, page no.89-108, January-2019, Available :http://www.jetir.org/papers/JETIR1901I14.pdf

"Temporal and Spatial Patterns of Nitrogen dioxide (NO2) and Formaldehyde (HCHO) in Delhi and Surrounding Regions: Analysis Using Satellite Data", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 1, page no. pp89-108, January-2019, Available at : http://www.jetir.org/papers/JETIR1901I14.pdf