Europlanet Science Congress 2021
Virtual meeting
13 – 24 September 2021
Europlanet Science Congress 2021
Virtual meeting
13 September – 24 September 2021
EPSC Abstracts
Vol. 15, EPSC2021-702, 2021, updated on 22 Jul 2021
https://doi.org/10.5194/epsc2021-702
European Planetary Science Congress 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Asymmetric impacts on Mars' polar vortices from the 2018 Global Dust Storm

Paul Streeter1, Stephen Lewis1, Manish Patel1,2, James Holmes1, Anna Fedorova3, David Kass4, and Armin Kleinböhl4
Paul Streeter et al.
  • 1The Open University, School of Physical Sciences, Milton Keynes, United Kingdom of Great Britain – England, Scotland, Wales (paul.streeter@open.ac.uk)
  • 2Space Science and Technology Department, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, U.K
  • 3Space Research Institute of the Russian Academy of Sciences (IKI RAS), Moscow, Russia
  • 4Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, U.S.A.

Introduction:  Like Earth, Mars possesses dynamical atmospheric features known as polar vortices. These are regions of cold, isolated polar air surrounded by powerful westerly wind jets which can create barriers to transport of atmospheric dust, water, and chemical species. They have a complex and asymmetrical (north/south) relationship with atmospheric dust loading [1]. Regional and global dust events have been shown to cause rapid vortex displacement [2,3] in the northern vortex, while the southern vortex appears more robust.

Unlike Earth, Mars also experiences planet-encircling Global Dust Storms: spectacular, planet-spanning events which dramatically increase atmospheric dust loading. The most recent such event in 2018 (beginning at northern autumn equinox) [4] was observed by multiple spacecraft, including the ExoMars Trace Gas Orbiter (TGO) and the Mars Reconnaissance Orbiter (MRO), enabling the opportunity to study its effects on the polar vortices in detail.

We do this by assimilating [5] spacecraft data from TGO’s Atmospheric Chemistry Suite (ACS) [6,7] and MRO’s Mars Climate Sounder (MCS) [8,9] into the LMD-UK Mars Global Climate Model [10], a 4D numerical model of the martian atmosphere.

Results: We present our recently published results [11], where we find that the 2018 GDS had asymmetrical impacts in each hemisphere: the northern polar vortex remained relatively robust, while the southern polar vortex was significantly disrupted. This asymmetry was due to both the storm’s latitudinal extent, which was greater in the south than in the north, and its timing, occurring as the southern vortex was already decaying after equinox. Both polar vortices and especially the northern showed reductions in their ellipticity, and this correlated with a reduction in high-latitude stationary wave activity in both hemispheres. We show that the characteristic elliptical shape of Mars’ polar vortices is the pattern of the stationary waves; this was suppressed during the storm by the shifting of the polar jet away from regions of high mechanical forcing in the north, and by the reduced polar jet due to the decreased meridional temperature gradient in the south. These asymmetric effects suggest enhanced transport into the southern, but not northern, polar region during GDS around northern autumn equinox, as well as more longitudinally symmetric transport around both poles.

 

References: [1] Waugh, D. W. et al (2016) J. Geophys. Res. Planets, 121, 1770-1785. [2] Guzewich, S. D. et al (2016) Icarus, 278, 100-118. [3] Mitchell, D. M. et al (2015) Q.J.R. Meteorol. Soc., 141, 550-562. [4] Kass, D. M et al (2019) GRL, 47(23). [5] Lewis, S. R. et al (2007) Icarus, 192(2). [6] Korablev, O. et al (2018) Space Sci. Rev., 214(7). [7] Fedorova, A. A. et al (2020) Science, 367(6475). [8] McCleese, D. J. et al (2007) JGR (Planets), 112(E5). [9] Kleinböhl, A. et al (2009) JGR (Planets), 114(E10). [10] Forget, F. et al (1999) JGR (Planets), 104(E10). [11] Streeter, P. M. et al (2021) JGR (Planets), e2020JE006774.

How to cite: Streeter, P., Lewis, S., Patel, M., Holmes, J., Fedorova, A., Kass, D., and Kleinböhl, A.: Asymmetric impacts on Mars' polar vortices from the 2018 Global Dust Storm, European Planetary Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-702, https://doi.org/10.5194/epsc2021-702, 2021.

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