https://www.nature.com/articles/s41612-024-00664-8
*Authors* Hongwei Sun, Stephen Bourguet, Lan Luan & David Keith *30 May 2024* *Citations*: Sun, H., Bourguet, S., Luan, L. et al. Stratospheric transport and tropospheric sink of solar geoengineering aerosol: a Lagrangian analysis. npj Clim Atmos Sci 7, 115 (2024). https://doi.org/10.1038/s41612-024-00664-8 *Abstract* Stratospheric aerosol injection (SAI) aims to reflect solar radiation by increasing the stratospheric aerosol burden. To understand how the background circulation influences stratospheric transport of injected particles, we use a Lagrangian trajectory model (lacking numerical diffusion) to quantify particles’ number, flux, lifetime, and tropospheric sinks from a SAI injection strategy under present-day conditions. While particles are being injected, stratospheric particle number increases until reaching a steady-state. During the steady-state, the time series of particle number shows a dominant period of ~2 years (rather than a 1-year cycle), suggesting modulation by the quasi-biannual oscillation. More than half of particles, injected in the tropical lower stratosphere (15° S to 15° N, 65 hPa), undergo quasi-horizontal transport to the midlatitude. We find a zonal asymmetry of particles’ tropospheric sinks that are co-located with tropopause folding beneath the midlatitude jet stream, which can help predict tropospheric impacts of SAI (e.g., cirrus cloud thinning). [image: figure 1] <https://www.nature.com/articles/s41612-024-00664-8/figures/1> Time series of the number of particles (black line) in the stratosphere, with three stages divided by the red dashed lines. Evaluations of particle distribution and transport in the stratosphere. [image: figure 4] <https://www.nature.com/articles/s41612-024-00664-8/figures/4> a Spatial distribution (latitude vs. altitude) of zonally integrated particle number concentration (with a unit of particles per square meter). b Particle number N (red values with the unit of particles), number flux *F* (blue values with a unit of particles per year), and lifetime *L* (purple values with a unit of years) in or between different regions (black boxes) during the steady-state stage (2005.01–2010.01). The injection rate is scaled to 100 particles per year and all other values are scaled correspondingly. *Source: Nature* -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAHJsh99Y%2BFQRoUBKoab4P2XAO6MuLcfAmFC3n3cY6LUAACyWFA%40mail.gmail.com.
