Today, I wanted to share a bit of the analysis we’re working on for Planet Four. Taking the Planet Four fan and blotch catalog from Season 1 and 2 of the HiRISE monitoring campaign, we’re now looking at what the average/dominant wind directions, derived for your classifications is telling us about the Martian south polar surface winds.
I wanted to show an example of what the science team is doing this. Tim Michaels has joined the science team and he’s an expert on climate modeling. We’re using the MRAMS (Mars Regional Atmospheric Modeling System) climate model/computer simulation to compare the fan directions to what direction is expected from the simulation. MRAMS is taking all the physics that we have about atmospheres and how we think these processes are working and computes what the atmosphere is doing and its conditions. We’re working on comparing the output of MRAMS to the wind directions we infer from the Planet Four fan directions.
Below is an example of one of the types of plots the team has been looking at. Here we show where the dominant fan direction is pointing in the full HiRISE frame from the Planet Four fan catalog. Think of this has telling you where the wind is headed. Each arrow represents a HiRISE observation image taken as part of the Spring/Summer monitoring season. The color of the arrows tell you which block of the Spring/Summer season the image was taken. For timekeeping on Mars, we use L_s, solar longitude, where Mars is located in in orbit around the Sun. L_s=180 is early Southern Spring. 220 is into early Southern Summer. We have 2 Mars Years as part of the current Planet Four catalog We plot the directions from each separately in the left and middle plot, and jointly all together in the right most plot. The left and middle plot show the topography that was used by the MRAMS model and the right most post shows the highest resolution topography measured by the Mars Global Surveyor’s Mars Orbiter Laser Altimeter.
Plots like this help the team look at the impact of topography and the structure of the local surface that might be contributing to how the wind blows. From this image we see that Giza is on the edge of an area where the elevation is dropping as we move more northward in latitude. Here we can see that the topography is likely playing a significant roll with the wind likely traveling from the highest elevations region (bottom of the plot) to the lower elevations. We’ll be able to compare with the detailed ouptut from the MRAMS simulation, but the topographic plots help us put the results from MRAMS in context. The simulation will tells us what direction it think the wind is blowing, but it won’t tell us necesarily why. These topographic plots help us add more explanation to the story.