Mark E. Hervig

and 5 more

Our solar system is filled with meteoric particles, or cosmic dust, which is either interplanetary or interstellar in origin. Interstellar dust (ISD) enters the heliosphere due to the relative motion of the sun and the interstellar flow. Interplanetary dust (IPD) comes primarily from asteroid collisions or comet sublimation, and comprises the bulk of material entering Earth’s atmosphere. This study examines variations in ISD and the IPD flux at Earth using observations from three different satellite techniques. First are size-resolved in situ meteoroid detections by the Ulysses spacecraft, and second are in situ indirect dust observations by Wind. Third are measurements of meteoric smoke in the mesosphere by the Solar Occultation For Ice Experiment (SOFIE). Wind observations are sorted into the interstellar and interplanetary components. Wind ISD show the anticipated correlation to the 22-yr. solar magnetic cycle, and are consistent with model predictions of ISD. Because Wind does not discriminate particle size, the IPD measurements were interpreted using meteoric mass distributions from Ulysses observations and from different models. Wind observations during 2007-2020 indicate a total meteoric influx at Earth of 22 metric tons per day (t d-1), in reasonable agreement with long-term averages from SOFIE (25 t d-1) and Ulysses (32 t d-1). The SOFIE and Wind influx time series both show an unexpected correlation to the 22-yr. solar cycle. This relationship could be an artifact, or may indicate that IPD responds to changes in the solar magnetic field.

Mark E. Hervig

and 5 more

Measurements from the Solar Occultation For Ice Experiment (SOFIE) are used to characterize meteoric smoke and meteor influx in both hemispheres. 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, it has the same elemental abundance as incoming meteoroids, and it is anticipated by theory and laboratory experiments. Treating mesospheric smoke as olivine furthermore brings closure in terms of the ablated and total meteoric influx determined here from SOFIE and a recent and independent investigation based on models and observations. SOFIE observations from 2007 - 2021 indicate a global ablated meteoric influx of 7.3 +/- 2.0 metric tons per day (t/d), which corresponds to a total influx (ablated plus surviving material) of 25.0 +/- 7.0 t/d. Finally, SOFIE indicates less smoke in the polar winter SH compared to NH winter. Finally, the results indicate stronger descent in the NH polar winter mesosphere than in the SH winter. This hemispheric asymmetry is indicated by smoke and water vapor results from both SOFIE and WACCM.