Inference of surface concentrations of nitrogen dioxide (NO2) in Colombia from tropospheric columns of the ozone measurement instrument (OMI)

For the first time, maps of surface concentration of nitrogen dioxide (NO₂) are presented for the Colombian territory. NO₂ surface concentrations for the year 2007 are inferred based on two sources of tropospheric NO₂ column data: (1) a simulation using a three-dimensional global model (GEOS-Chem) and (2) measurements made by the ozone monitoring instrument (OMI) onboard the NASA Aura satellite. Results show monthly averages between 0.1 and 6 ppbv. We compare these inferred values to corrected ground measurements of NO₂. We find correlation coefficients of up to 0.91 between the inferred data and the corrected observational data. A significant source of NO₂ is biomass burning, which can be diagnosed by data of fire radiative power (FRP) from the Monitoring of Atmospheric Composition and Climate (MACC) reanalysis. We find a close relationship between high values of inferred NO₂ surface concentrations and biomass burning for a large area which encompasses the departments of Caquetá, Meta, Guaviare, Vichada, and Putumayo.