11:45 AM - 12:00 PM
[PPS05-05] Constraining the MSL-SAM Methane Detected Source Location Through Mars Regional Atmospheric Modeling System (MRAMS)
Keywords:Mars, Mars Atmosphere, Mars Atmosphere modeling, methane detection on Mars, Curiosity rover
In both scenarios, the release is assumed to take place near the season when the rise of concentration was first noted (Ls336). This is a transitional time at Gale Crater, when the flushing winds are giving way to a rapid mixing scenario but slower compared to Ls270. As expected, Ls270 was shown to be a faster mixing season when air within and outside the crater was well mixed by strong, flushing, northerly flow and large amplitude breaking mountain waves: air flowing downslope (buoyancy and dynamical forcing) at night penetrate all the way to the surface. In the experiments, all inside mass is gone from crater after just 10 hours. At other seasons only ~50% of inside mass stays in crater after 10 hours and simulations indicate that the air flowing down the crater rims does not easily make it to the crater floor. Instead, the air encounters very cold and stable air pooled in the bottom of the crater, which forces the air to glide right over the colder, more dense air below. Thus, the mixing of near surface crater air with the external environment in these seasons is potentially rapid but slower than Ls270. Timescale of mixing in MRAMS model is on the order of 1 sol regardless of season, much faster than previously estimated. Duration of CH4 peak observed by SAM is ~100 sols (assuming no high frequency variations). In the second scenario (puntual methane release outside Gale crater), methane arriving rover location from outside crater is diluted by approx. 6 orders of magnitude after just 12 hours. Therefore, either there is a continuous release inside the crater (more likely) to counteract mixing, or the methane is widely distributed so that mixing doesn’t matter, or a local release outside the crater have to be continuous and very large magnitude (unlikely). In order to test that, new experiments are being performed with continuous methane releases both inside and outside the crater. The calculations of methane fluxes will be made for clathrates at different depths and formed from a gas phase containing 90%, 50% and 10% of CH4. Also, back trajectory calculations will be used to determine origin of air at rover location as a function of time.