The surface deposition of meteoric smoke particles - possible climate impact

There are large uncertainties in the transport and surface deposition of upper atmospheric particles, such as meteoric smoke particles (MSPs) formed in the upper mesosphere. Here we use a 3D chemistry-climate model (CCM) to simulate the transport and deposition of MSPs from the upper mesosphere. The CCM was first validated by predicting the deposition of plutonium-238 oxide nanoparticles formed after the ablation of a power unit in the upper stratosphere (~11^o S) in 1964. The observed hemispheric asymmetry and timescale of Pu-238 deposition is well-captured. In the case of MSPs, the model predicts more deposition in Greenland than Antarctica by a factor of ~15, in agreement with ice core measurements. The strongest MSP deposition is predicted to occur at mid-latitudes, providing a significant source of Fe fertilization to the Southern Ocean where there is a shortage of bio-available Fe. The resulting increase in CO₂ drawdown may have a significant climate impact. Map of annual mean Fe deposition rate (μmol Fe m^-2 y^-1)