5:15 PM - 7:15 PM
[PPS09-P18] Characteristics of dust plumes detected during Martian regional dust storms by MRO-MCS observations
Keywords:Mars, Regional dust storm, dust plume, B storm
The Martian atmosphere contains dust particles, ~1um in size, originating from surface rocks. These dust particles absorb solar visible light and undergo radiative transfer processes, absorbing and emitting thermal infrared radiation, significantly affecting the thermal balance of the Martian atmosphere. In particular, dust heated near the surface by solar light initiates convection, leading to dust lifting and resulting in dust storms.
Mars has an elliptical orbit, and dust storm activity increases near the perihelion. Dust storms on Mars can be classified into three types based on their spatiotemporal scale: local dust storms, regional dust storms, and global dust storms. In Martian years without a global dust storm, three regional dust storms occur near the perihelion. Kass et al. (2016) investigated the temperature during regional dust storms and classified them into three types (A, B, and C storms). While A and C storms, which are associated with baroclinic waves, occur in the mid-latitudes of both hemispheres (Martín-Rubio et al., 2024), B storms occur only poleward of 65°S (Kass et al., 2016; Batterson et al., 2023).
In this study, we captured structures, referred to as dust plumes, where high dust concentrations reach ~10Pa during the B storm periods, using dust opacity and temperature vertical profiles obtained by the Mars Climate Sounder (MCS) instrument on Mars Reconnaissance Orbiter (MRO). MRO is in a sun-synchronous polar orbit with a longitude spacing of 27° and an orbital period of 112 minutes (McCleese et al., 2007). Therefore, near the poles, latitude-height cross-sections can be obtained by rotating ~30° in the longitude direction within a 2-hour period. During the B storm period (Ls=250-290°) in Mars Year 35, we analyzed the latitude-pressure distributions of each orbit at 30°S-90°S. As a result, several dust plumes were found. The dust plumes were ~1000-1800 km wide in latitudinal direction, as obtained along the satellite's orbit, reached a pressure height of ~3Pa, and had a dust opacity of ~10-4 km-1. The dust mixing ratio, defined as dust opacity normalized by atmospheric mass density, was higher inside the dust plumes compared to the surface in some cases.
Since the observational data used cannot capture dust plumes continuously in space and time, it is not yet clear whether the dust plumes are connected to the surface or completely detached from it. If they are detached, they may be a candidate for generating Detached Dust Layers (McCleese et al., 2010; Heavens et al., 2011a; Heavens et al., 2011b; Spiga et al., 2013) . The characteristics of the dust plumes detected in the present study align with the numerical simulation results by Batterson et al. (2023), which shows that dust plumes extend ~400-1500 km in longitude and reach a pressure height of ~3Pa. Future studies are required to determine whether such dust plumes occur in other Martian years and how frequently they do.
Mars has an elliptical orbit, and dust storm activity increases near the perihelion. Dust storms on Mars can be classified into three types based on their spatiotemporal scale: local dust storms, regional dust storms, and global dust storms. In Martian years without a global dust storm, three regional dust storms occur near the perihelion. Kass et al. (2016) investigated the temperature during regional dust storms and classified them into three types (A, B, and C storms). While A and C storms, which are associated with baroclinic waves, occur in the mid-latitudes of both hemispheres (Martín-Rubio et al., 2024), B storms occur only poleward of 65°S (Kass et al., 2016; Batterson et al., 2023).
In this study, we captured structures, referred to as dust plumes, where high dust concentrations reach ~10Pa during the B storm periods, using dust opacity and temperature vertical profiles obtained by the Mars Climate Sounder (MCS) instrument on Mars Reconnaissance Orbiter (MRO). MRO is in a sun-synchronous polar orbit with a longitude spacing of 27° and an orbital period of 112 minutes (McCleese et al., 2007). Therefore, near the poles, latitude-height cross-sections can be obtained by rotating ~30° in the longitude direction within a 2-hour period. During the B storm period (Ls=250-290°) in Mars Year 35, we analyzed the latitude-pressure distributions of each orbit at 30°S-90°S. As a result, several dust plumes were found. The dust plumes were ~1000-1800 km wide in latitudinal direction, as obtained along the satellite's orbit, reached a pressure height of ~3Pa, and had a dust opacity of ~10-4 km-1. The dust mixing ratio, defined as dust opacity normalized by atmospheric mass density, was higher inside the dust plumes compared to the surface in some cases.
Since the observational data used cannot capture dust plumes continuously in space and time, it is not yet clear whether the dust plumes are connected to the surface or completely detached from it. If they are detached, they may be a candidate for generating Detached Dust Layers (McCleese et al., 2010; Heavens et al., 2011a; Heavens et al., 2011b; Spiga et al., 2013) . The characteristics of the dust plumes detected in the present study align with the numerical simulation results by Batterson et al. (2023), which shows that dust plumes extend ~400-1500 km in longitude and reach a pressure height of ~3Pa. Future studies are required to determine whether such dust plumes occur in other Martian years and how frequently they do.