Martian boundary layer wind profiles during the landings of Viking and InSight

Interaction between mesoscale, synoptic and planetary scale circulations on Mars can combine to produce locally complex winds that make interpretation of lander wind data a challenge. We investigate the structure of the boundary layer winds by obtaining new wind speed and directions from trajectory analysis of the Viking 1, Viking 2 and InSight landings. We use the new wind data for InSight together with a column model to investigate the near-surface winds at the InSight landing site. We use our Trajectory Model and Analysis Tool (TMAT) to verify wind data obtained by Viking lander 1 (VL-1) as it passed through a region of strong winds. This is important as the winds may be evidence of Western Boundary Currents. We constrain the vertical extent of this wind layer. We also verify the wind data for Viking lander 2 (VL-2). For VL-2 the winds remain constant from parachute deployment to lander release below which there is a large change in wind direction. For InSight our analysis indicates the wind speeds remain approximately constant with altitude. We found the wind blows from the west in the upper part of InSight's descent and from the north northwest closer to the surface. We use our new TMAT inferred wind data for InSight to initialise the winds of a column model (University of Helsinki/Finnish Meteorological Institute). We investigate the influence of slope winds on the local winds at the InSight landing site. Our results demonstrate that Martian slopes and large-scale circulations can interact in a complex way to produce the near-surface wind patterns as observed by InSight. We have been able to obtain new wind velocity data at several altitudes and locations on Mars by utilizing atmospheric modelling and the known locations of landed hardware from Mars surface missions. We have applied these new velocity data to investigate the interactions of large-scale winds and the Martian topography. •New wind data during the descent of the Viking and InSight landers are provided.•Vertical structure of the winds during the landings are inferred.•Previously reported high speed winds during the Viking lander 1 are verified.•Atmospheric circulations at the InSight landing site are investigated.•. Modelled interactions between large scale and slope winds.are consitent with observations.