Global model datasets (GA4 UM-UKCA) for size-resolved particle concentrations in the background stratospheric aerosol layer

This dataset is from a series of TimeSlice-2000 free-running interactive stratospheric aerosol simulations of the background stratospheric aerosol layer with the UM-UKCA composition-climate model.   The model experiments assess the background state of the stratospheric aerosol layer, focused to 5-year monthly-means from a so-called “TimeSlice 2000” run, that is with the model repeating year-2000 boundary conditions and anthropogenic emissions throughout this 11-year model run (xnelf).The simulations are with UM-UKCA model at GA4 (Walters et al., 2014), the aerosol scheme GLOMAP-mode upgraded to v8.2 for these runs (Dhomse et al. 2020), as applied for the “MajorVolc” datasets for Agung, El Chichon and Pinatubo, and further evaluated in Quaglia et al., 2023., These runs aligned with the Historical Eruption SO2 emissions Assessment experiment within the ISA-MIP model intercomparison activity for interactive stratospheric aerosol models (Timmreck et al., 2018).

The datasets stored within this zenodo archive are all 5-year monthly-means, and in this v1.1 archive are only for the accumulation-insoluble mode (mode 6), i.e. size-resolved N for the meteoric-sulphuric particles only (the original v1 includes all particles). Stored here are 3D monthly-mean size-resolved particle number concentrations for 4 different particle size-cuts, for Dp>10nm, Dp>70nm, Dp>300nm and Dp> 500nm.

The N(Dp>10nm) and N(Dp>70nm) are dataset from Figure 3b and 3c of the manuscript “Stratospheric aerosol from above”, by Mann et al. (2026), submitted for JGR commentary article in October 2025.   The commentary aligns directly to ground-breaking field measurements with the PALMS-NG laser-ablation mass spectrometer instrument installed on the WB-57 high-altitude aircraft.  The JGR paper by Lawler et al. (2025) finds that ~90% of sampled stratospheric aerosol particles in deep vortex air contain a signature of meteoric metals.The findings are consistent with refractory particle measurements from European Arctic high-altitude aircraft (Curtius et al., 2005; Weigel et al., 2014), and high-latitude total stratospheric aerosol measurements from the University of Wyoming high-altitude balloon system (Campbell and Deshler, 2014; Norgren et al., 2024) which both show increasing mixing ratios of particles between altitudes of 25km and 35km.   These measurements have been interpreted as indicating a source of stratospheric aerosol from above, likely of meteoric origin.

References :

Campbell, P. and Deshler, T. (2014): “Condensation nuclei measurements in the midlatitude (1982–2012) and Antarctic (1986–2010) stratosphere between 20 and 35km”, J. Geophys. Res.: Atmos., vol. 119, 137–152, https://doi.org/10.1002/2013JD019710 

Curtius, J., Weigel, R., Vössing, H.-J. et al. (2005): “Observations of meteoric material and implications for aerosol nucleation in the winter Arctic lower stratosphere derived from in situ particle measurements”, Atmos. Chem. Phys., 5, 3053–3069, https://doi.org/10.5194/acp-5-3053-2005 .

Dhomse S. S, Mann G.W, Antuña Marrero J.-C, et al. (2020). “Evaluating the simulated radiative forcings, aerosol properties, & stratospheric warmings from the 1963 Mt Agung, 1982 El Chichón & 1991 Pinatubo volcanic aerosol clouds”, Atmos. Chem. Phys. 20(21), 13627-13654 , https://doi.org/10.5194/acp-20-13627-2020

Lawler, M.J.,Schill, G.P, Murphy,D.M et al., (2025): “The composition and stratospheric fate of aerosol particles originating in the polar vortex”, J. Geophys. Res. Atmos.,,130, https://doi.org/10.1029/2025JD043530 .

Mann, G. W., Weigel, R., Bardeen, C., Marshall, L. R., Brodowsky, C., Norgren, M. and Toon, O.B. (2026): Stratospheric aerosol from above: Laser-ablation mass spectrometer samples polar vortex air for the first time (Commentary article on JGR in press article by Lawler et al., ”The composition and stratospheric fate of aerosol particles originating in the polar vortex”), in review for publication in J. Geophys. Res., Atmos. (submitted October 2025, reviews received March 2026).

Norgren, M., Kalnajs, L. and Deshler, T. (2024): “Measurements of total aerosol concentration in the stratosphere: A new balloon‐borne instrument and a report on the existing measurement record”, J. Geophys. Res., 129, e2024JD040992. https://doi.org/10.1029/2024JD040992 .

Quaglia, I., Timmreck, C., Niemeier, U. et al. (2023): “Interactive stratospheric aerosol models’ response to different amounts and altitudes of SO2 injection during the 1991 Pinatubo eruption”, Atmos. Chem. Phys., 23, 921–948 https://doi.org/10.5194/acp-23-921-2023 .

Timmreck, C., Mann, G. W., Aquila, V., et al. (2018): “The Interactive Stratospheric Aerosol Model Intercomparison Project: motivation and experimental design”, Geosci. Mod. Dev., 11, 2581-2608, https://doi.org/10.5194/gmd-11-2581-2018 .

Walters, D. et al. (2014): “The Met Office Unified Model Global Atmosphere 4.0 and JULES Global Land 4.0 configurations”, Geosci. Model Dev., 7, 361–386, https://doi:10.5194/gmd-7-361-2014 .

Weigel, R., Volk, C. M., Kandler, K. et al. (2014): “Enhancements of the refractory submicron aerosol fraction in the Arctic polar vortex: feature or exception?”, Atmos. Chem. Phys., 14, 12319–12342, https://doi.org/10.5194/acp-14-12319-2014 .