The detection of enhanced carbon monoxide abundances in remotely sensed infrared spectra of a forest fire smoke plume

Abstract

Nadir looking infrared spectra of a forest fire smoke plume off the south shore of Long Island, New York, were obtained from a NASA ER‐2 aircraft during two spatially coincident over‐flights on the morning of August 25, 1995. These spectra exhibit enhanced CO column densities at the same geographic locations over the smoke plume on both over‐flights with a peak CO column density ∼2.6 × 10¹⁸cm⁻², ∼6σ above the clear air background. Meteorological conditions suggest the smoke plume was confined to the planetary boundary layer (PBL), pressures ≥ 850 mb, and perhaps to a thin region near the top of the PBL. Constraining the excess CO to the PBL yields a CO mixing ratio ∼1,400 ppbv. Further constraining the CO to the model layer nearest the top of the PBL, 852–878 mb, yields‐4,300 ppbv. From the spatial overlap of the spectra, the estimated width of the CO rich portion of the plume is ≤ 2.8 km vs. a plume width of ∼5 km in GOES‐8 satellite visible images.