edu.ucar.opensky::articles:24739 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-24T23:03:54.258567 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7dr2zzb Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements 2021-09-16T00:00:00Z publication https://n2t.org/ark:/85065/d7dr2zzb https://doi.org/10.5194/acp-21-13729-2021 Guo, H. author Flynn, C. M. author Prather, M. J. author Strode, S. A. author Steenrod, S. D. author Emmons, Louisa K. author Lacey, Forrest author Lamarque, Jean-François author Fiore, A. M. author Correa, G. author Murray, L. T. author Wolfe, G. M. author St. Clair, J. M. author Kim, M. author Crounse, J. author Diskin, G. author DiGangi, J. author Daube, B. C. author Commane, R. author McKain, K. author Peischl, J. author Ryerson, T. B. author Thompson, C. author Hanisco, T. F. author Blake, D. author Blake, N. J. author Apel, Eric C. author Hornbrook, Rebecca author Elkins, J. W. author Hintsa, E. J. author Moore, F. L. author Wofsy, S. author UCAR/NCAR - Library publisher The NASA Atmospheric Tomography (ATom) mission built a photochemical climatology of air parcels based on in situ measurements with the NASA DC-8 aircraft along objectively planned profiling transects through the middle of the Pacific and Atlantic oceans. In this paper we present and analyze a data set of 10 s (21(m) merged and gap-filled observations of the key reactive species driving the chemical budgets of O-3 and CH4 (O-3, CH4, CO, H2O, HCHO, H2O2, CH3OOH, C2H6, higher alkanes, alkenes, aromatics, NOx, HNO3, HNO4, peroxyacetyl nitrate, other organic nitrates), consisting of 146 494 distinct air parcels from ATom deployments 1 through 4. Six models calculated the O-3 and CH4 photochemical tendencies from this modeling data stream for ATom 1. We find that 80 %-90 % of the total reactivity lies in the top 50 % of the parcels and 25 %-35 % in the top 10 %, supporting previous model-only studies that tropospheric chemistry is driven by a fraction of all the air. In other words, accurate simulation of the least reactive 50 % of the troposphere is unimportant for global budgets. Surprisingly, the probability densities of species and reactivities averaged on a model scale (100 km) differ only slightly from the 2 km ATom data, indicating that much of the heterogeneity in tropospheric chemistry can be captured with current global chemistry models. Comparing the ATom reactivities over the tropical oceans with climatological statistics from six global chemistry models, we find excellent agreement with the loss of O-3 and CH4 but sharp disagreement with production of O-3. The models sharply underestimate O-3 production below 4 km in both Pacific and Atlantic basins, and this can be traced to lower NOx levels than observed. Attaching photochemical reactivities to measurements of chemical species allows for a richer, yet more constrained-towhat-matters, set of metrics for model evaluation. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. None eng geoscientificInformation