edu.ucar.opensky::articles:21216 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-25T16:10:35.582219 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7zc85g0 Deriving global OH abundance and atmospheric lifetimes for long-lived gases: A search for CH3CCl3 alternatives 2017-11-16T00:00:00Z publication https://n2t.org/ark:/85065/d7zc85g0 https://doi.org/10.1002/2017JD026926 Liang, Q. author Chipperfield, M. P. author Fleming, E. L. author Abraham, N. L. author Braesicke, P. author Burkholder, J. B. author Daniel, J. S. author Dhomse, S. author Fraser, P. J. author Hardiman, S. C. author Jackman, C. H. author Kinnison, Douglas E. author Krummel, P. B. author Montzka, S. A. author Morgenstern, O. author McCulloch, A. author Mühle, J. author Newman, P. A. author Orkin, V. L. author Pitari, G. author Prinn, R. G. author Rigby, M. author Rozanov, E. author Stenke, A. author Tummon, F. author Velders, G. J. M. author Visioni, D. author Weiss, R. F. author UCAR/NCAR - Library publisher An accurate estimate of global hydroxyl radical (OH) abundance is important for projections of air quality, climate, and stratospheric ozone recovery. As the atmospheric mixing ratios of methyl chloroform (CH3CCl3) (MCF), the commonly used OH reference gas, approaches zero, it is important to find alternative approaches to infer atmospheric OH abundance and variability. The lack of global bottom-up emission inventories is the primary obstacle in choosing a MCF alternative. We illustrate that global emissions of long-lived trace gases can be inferred from their observed mixing ratio differences between the Northern Hemisphere (NH) and Southern Hemisphere (SH), given realistic estimates of their NH-SH exchange time, the emission partitioning between the two hemispheres, and the NH versus SH OH abundance ratio. Using the observed long-term trend and emissions derived from the measured hemispheric gradient, the combination of HFC-32 (CH2F2), HFC-134a (CH2FCF3, HFC-152a (CH3CHF2), and HCFC-22 (CHClF2), instead of a single gas, will be useful as a MCF alternative to infer global and hemispheric OH abundance and trace gas lifetimes. The primary assumption on which this multispecies approach relies is that the OH lifetimes can be estimated by scaling the thermal reaction rates of a reference gas at 272K on global and hemispheric scales. Thus, the derived hemispheric and global OH estimates are forced to reconcile the observed trends and gradient for all four compounds simultaneously. However, currently, observations of these gases from the surface networks do not provide more accurate OH abundance estimate than that from MCF. 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 2017 American Geophysical Union. None eng geoscientificInformation