부산대학교 도서관

We report on the direct measurements of zonal winds around 80 km altitude during the 2018 planet-encircling dust event (PEDE) by infrared (IR) heterodyne spectroscopy. The observed Doppler shifts assume intense retrograde (easterly) winds (208 ± 17 m s-1, 159 ± 20 m s-1, 211 ± 20 m s-1 on June 21, June 27, August 31, 2018, respectively) in the equatorial region during the 2018 PEDE. This is significantly stronger than those during non-storm conditions reported by the previous study (Sonnabend et al., 2012, https://doi.org/10.1016/j.icarus.2011.11.009). The substantial retrograde wind during the PEDE is qualitatively consistent with the predictions by the Mars general circulation models (MGCMs), however, the observed wind on 31, August, are of a larger magnitude. We evaluated the mechanism of acceleration using the output from a high-resolution MGCM. We find out that the stronger winds are related to strengthening the meridional circulation across the equator and forcing by gravity waves. Plain Language Summary Planet-encircling dust events (PEDE) are spectacular phenomena that occasionally occur in the atmosphere of Mars. The atmospheric circulation on Mars is strongly influenced by dust events, which affect not only the lower atmosphere, but also the mesosphere. The ground-based mid-IR heterodyne spectroscopy was able to observe zonal winds around 80 km during the 2018 PEDE. We found intense retrograde (easterly) winds at the equator, which were much larger than those during non-storm conditions reported by the previous study. This study suggests that the intense retrograde winds during the PEDE were likely caused by the enhanced meridional circulation and smallscale gravity waves. [ABSTRACT FROM AUTHOR]