ACROSS_IMTNE_RambForest_AMS_BelowCanopy_L2

HR-ToF-AMS processed using Analysis Toolkit 1.65C and HR Analysis 1.25C focusing on V-mode due to higher signal stability.

Data averaging: 3 minutes.

Data calibration: Monodispersed ammonium nitrate (300 nm) used to derive NO3 IE and NH4 RIE. Monodispersed ammonium sulfate (300 nm) used to derive SO4 RIE.

Data treatment: Routine blanks were used to correct the nitrogen signal at the CHO+ signal, and CO2+ signal from collocated LICOR measuring ambient carbon dioxide.

Data products: Oxygen-to-carbon and hydrogen-to-carbon ratios calculated according to the “improved-ambient” methodology proposed by Canagaratna et al., 2015.
Nitrate signal split between ammonium nitrate and organic nitrate (pRONO2) following the methodology described in Day et al., 2022.

Location and inlet: Aerosol sampled below the canopy (4 m agl) on a PM2.5 inlet and through a nafion dryer.

References

Canagaratna, M.R., Jimenez, J.L., Kroll, J.H., Chen, Q., Kessler, S.H., Massoli, P., Hildebrandt Ruiz, L., Fortner, E., Williams, L.R., Wilson, K.R., Surratt, J.D., Donahue, N.M., Jayne, J.T., Worsnop, D.R., 2015. Elemental ratio measurements of organic compounds using aerosol mass spectrometry: Characterization, improved calibration, and implications. Atmos. Chem. Phys. 15, 253–272.

Day, D.A., Campuzano-Jost, P., Nault, B.A., Palm, B.B., Hu, W., Guo, H., Wooldridge, P.J., Cohen, R.C., Docherty, K.S., Huffman, J.A., de Sá, S.S., Martin, S.T., Jimenez, J.L., 2022. A systematic re-evaluation of methods for quantification of bulk particle-phase organic nitrates using real-time aerosol mass spectrometry. Atmos. Meas. Tech. 15, 459–483.