New Global Meteoric Smoke Observations From SOFIE: Insight Regarding Chemical Composition, Meteoric Influx, and Hemispheric Asymmetry

Measurements from the Solar Occultation For Ice Experiment (SOFIE) in both hemispheres are used to characterize meteoric smoke in the mesosphere and to estimate the meteoric flux into Earth's atmosphere. New smoke extinction retrievals from sunrise measurements in the Northern Hemisphere (NH) are presented, which complement the previously reported sunset observations in the Southern Hemisphere (SH). The sunrise observations are in good agreement with simulations from the Whole Atmosphere Community Climate Model (WACCM), for both the seasonal and height dependence of smoke in the mesosphere. The SOFIE-WACCM comparisons assumed that smoke in the mesosphere exists purely as Fe-rich olivine. This is justified because olivine is detected optically by SOFIE, meteoric ablation is predicted to inject similar quantities of the most abundant elements (Fe, Mg, and Si) into the mesosphere, and olivine is anticipated by theory and laboratory experiments. In addition, the ablated meteoric influx (AMI) and total meteoric influx determined from SOFIE assuming Fe-rich olivine is in agreement with a recent and independent investigation based on models and observations. SOFIE observations from 2007 to 2021 indicate a global AMI of 7.3 2.2 metric tons per day (t d(-1)), which corresponds to a total influx (ablated plus surviving material) of 24.7 7.3 t d(-1). Finally, the results indicate stronger descent in the NH polar winter mesosphere than in the SH winter. This hemispheric asymmetry at polar latitudes is indicated by smoke and water vapor results from both SOFIE and WACCM. Plain Language Summary Satellite observations from the Solar Occultation For Ice Experiment (SOFIE) detect meteoric remnants in Earth's mesosphere. Known as meteoric smoke, these nanometer sized aerosols are made primarily of iron, silica, and magnesium. SOFIE smoke observations in the Southern and Northern polar regions during 2007 - 2021 are in good agreement with simulations from the Whole Atmosphere Community Climate Model (WACCM). While SOFIE Indicates several smoke compositions, the present study suggests only Fe-rich olivine. This is justified because (a) olivine is optically detected by SOFIE, (b) meteor ablation injects similar quantities of Fe, Mg and Si, and (c) olivine is anticipated by theory and laboratory experiments. Additionally, the meteoric influx determined from SOFIE assuming olivine agrees with a recent and independent investigation based on models and observations. SOFIE indicates a global ablated meteoric influx of 7 metric tons/day (25 tons/day total influx). SOFIE and WACCM show hemispheric asymmetries in smoke and water vapor that are consistent with stronger transport in the Northern winter mesosphere than in the South. SOFIE shows a larger smoke asymmetry than the model, however, and this unresolved issue might be related to a missing asymmetry in the current model description of meteoric influx or smoke physics Key Points The composition of smoke in the mesosphere is consistent with iron-rich olivine Global ablated meteoric influx is estimated to be 7.3 +/- 2.2 metric tons/day, with a total influx of 24.7 +/- 7.3 tons/day Hemispheric asymmetries in smoke and H2O are consistent with stronger winter descent in the Northern polar mesosphere relative to the South