A Study of Daytime Convective Vortices and Turbulence in the Martian Planetary Boundary Layer Based on Half‐a‐Year of InSight Atmospheric Measurements and Large‐Eddy Simulations

Abstract

Studying the atmospheric planetary boundary layer (PBL) is crucial to understand the climate of a planet. The meteorological measurements by the instruments onboard InSight at a latitude of 4.5°N make a unique rich data set to study the active turbulent dynamics of the daytime PBL on Mars. Here we use the high‐sensitivity continuous pressure, wind, and temperature measurements in the first 400 sols of InSight operations (from northern late winter to midsummer) to analyze wind gusts, convective cells, and vortices in Mars’ daytime PBL. We compare InSight measurements to turbulence‐resolving large‐eddy simulations (LES). The daytime PBL turbulence at the InSight landing site is very active, with clearly identified signatures of convective cells and a vast population of 6,000 recorded vortex encounters, adequately represented by a power law with a 3.4 exponent. While the daily variability of vortex encounters at InSight can be explained by the statistical nature of turbulence, the seasonal variability is positively correlated with ambient wind speed, which is supported by LES. However, wind gustiness is positively correlated to surface temperature rather than ambient wind speed and sensible heat flux, confirming the radiative control of the daytime Martian PBL; and fewer convective vortices are forming in LES when the background wind is doubled. Thus, the long‐term seasonal variability of vortex encounters at the InSight landing site is mainly controlled by the advection of convective vortices by ambient wind speed. Typical tracks followed by vortices forming in the LES show a similar distribution in direction and length as orbital imagery.

Multi-model Meteorological and Aeolian Predictions for Mars 2020 and the Jezero Crater Region

“… 2019a ; Spiga et al. 2020 ); for understanding when and where surface dust is lifted, especially outside of dust storms when dust devil lifting may dominate (Basu et al. 2004 ; Kahre et al.…”

“…The DDA theory has been called into question by Spiga et al. ( 2020 ), who argue that IR radiative heating of the near-surface atmosphere is more important than sensible heating for Mars (unlike Earth) and should be considered. As part of a separate study, we have recently investigated the sensible vs. IR radiative heating of the near-surface atmosphere in MarsWRF and find that the two are generally of comparable magnitude (Wu et al.…”

A Comodulation Analysis of Atmospheric Energy Injection Into the Ground Motion at InSight, Mars

“…5. For sols 98-99 the wind speed is generally low with indistinct regimes and a constant, low level of turbulence as measured by its high wind gustiness (Spiga et al, 2020 Figure 6: Correlation coefficient map between the pressure and seismic envelopes. The envelopes are extracted from frequency windows spaced a half octave apart beginning from 0.01 Hz up to Nyquist.…”

“…Conversely, during the late-spring sols 290-291, close to summer solstice, surface temperatures reach a seasonal low while ambient wind speed is strong.The early summer period for sols 361-362 features rising surface temperature again, with ambient wind speed remaining strong. Of all those three cases, sols 98-99 are characterized by the strongest wind gustiness(Figure 9inSpiga et al (2020)).…”

Geophysical Observations of Phobos Transits by InSight

“…We performed a vortex search following the approach detailed in Banfield et al. (2020) and Spiga et al (2020). No convective vortex was detected during either the major Sol 501 Phobos transit or the Sols 96–97 transits, ruling out this seismic source.…”