Atmospheric aerosol particles before, during, and after a convective dust event on the Jornada experimental range as measured using Raman hyperspectral imaging

The effects of winds and local mineralogy on ambient aerosol composition are poorly understood. We measured the Raman spectra (RS) of ambient aerosol particles on the Jornada Experimental Range, a desert location in southern New Mexico, used these RS to group spectra by composition or spectral features, and compared the numbers of RS with the winds and minerology. An aerosol Raman hyperspectral imager was used to collect particles onto a tape and measure a hyperspectral Raman image in 15- or 20-min intervals. Over a 48 h period, 6306 RS were above the thresholds used and were analyzed further. Multiple RS may originate from the same particle. Of these 6306 RS, 2567 were classified as luminescence; 2647 contained the D and G peaks of DG Carbon (DGC, which includes soots, black carbon, and similar materials); 43 exhibited peaks consistent with CH stretching; and 130, 102, and 29 RS were consistent with quartz, carbonates (calcite and dolomite), and potassium feldspar, respectively. A convective dust event was concurrent with an increase in the number of RS of luminescent particles >20X the median; numbers of DGC RS in the interquartile range of DGC for the entire measurement period; RS consistent with quartz, calcite, iron oxides, feldspar, and anatase; and no RS consistent with oxalates or nitrates. This work shows that hyperspectral Raman imaging can help understand the time-dependent composition of ambient aerosol particles at time resolutions below an hour.

Automated summary

This study used hyperspectral Raman imaging technology to measure ambient aerosol particles in the Jornada Experimental Range in New Mexico, and classified the spectra based on composition or spectral features. The results showed that hyperspectral Raman imaging can help understand the composition of ambient aerosol particles at different time scales.