Abstract
The B storm is an annually recurring, regional-scale dust storm that
occurs over the south pole of Mars during southern summer solstice
season during years lacking a global dust storm [1]. The B storm
begins just after perihelion (Ls = 251°), reaches peak strength around
southern summer solstice (Ls = 270°), and decays through
~Ls = 290° [2]. The B storm is associated with
mid-level atmospheric warming in which 50 Pa (2.5 scale heights)
temperatures increase to over 200 K. Mid-level dust concentrations more
than triple during the B storm, exceeding 4 ppm throughout the duration
of the storm and exceeding 10 ppm at peak strength (Ls = 270°)
[1,2]. Our observational analysis, which was presented at AGU in
2020, shows that elevated dust concentrations (> 4 ppm) and
associated warming (> 200 K) are observable as high as 25
Pa during peak intensity, and that the B storm is a
southwestward-propagating storm that develops over 60° S and strengthens
as it travels poleward [2,3]. We have since carried out simulations
of B storms using the NASA Ames Mars Global Climate Model (MGCM), which
is based on the NOAA/GFDL cubed-sphere finite volume dynamical core, at
high spatial (1x1°, 60x60 km) resolution. We find that B storm dust is
lofted upwards of 50 Pa by episodic pluming events somewhat resembling
the rocket dust storms described in Spiga et al. (2013) [4].
Detached dust layers sometimes form from these plumes at altitudes
between 25-3 Pa (3-5 scale heights). These detached layers maintain
altitude for ~1 sol before the sedimentation rate of the
dust exceeds the upward vertical velocity generated by the radiative
heating of the suspended dust [5]. We will present results from the
MGCM-simulated B storm using three-dimensional animations to illustrate
the hourly evolution of the dust that is lofted during the storm. 1.
Kass D. M. et al. (2016). Geophs. Res. Letters, 43, 6111–6118. 2.
Batterson, C.M.L. et al. (2021). Scholarworks, SJSU Master’s Theses,
5174. 3. Batterson, C.M.L. et al. (2020). Martian B Storm Evolution:
Modeling Dust Activity over the Receding South Polar CO2 Ice Cap at
Southern Hemisphere Summer Solstice, Abstract (P080-0002) presented at
2020 AGU Fall Meeting, 1-17 Dec. 4. Spiga, A. et al. (2013). JGR:
Planets, 118(4), 746-767. 5. Daerden, F. et al. (2015). Geophs. Res.
Letters, 42, 7319-7326.