GRL (2024) https://doi.org/10.1029/2023GL107224
A. Brines, M. A. López-Valverde, B. Funke, F. González-Galindo, S. Aoki, G. L. Villanueva, J. A. Holmes, D. A. Belyaev, G. Liuzzi, I. R. Thomas, J. T. Erwin, U. Grabowski, F. Forget, J. J. Lopez-Moreno, J. Rodriguez-Gomez, F. Daerden, L. Trompet, B. Ristic, M. R. Patel, G. Bellucci, A. C. Vandaele
Here we present water vapor vertical profiles observed with the ExoMars Trace Gas Orbiter/Nadir and Occultation for MArs Discovery instrument during the perihelion and Southern summer solstice season (LS = 240°–300°) in three consecutive Martian Years 34, 35, and 36. We show the detailed latitudinal distribution of H2O at tangent altitudes from 10 to 120 km, revealing a vertical plume at 60°S–50°S injecting H2O upward, reaching abundance of about 50 ppmv at 100 km. We have observed this event repeatedly in the three Martian years analyzed, appearing at LS = 260°–280° and showing inter-annual variations in the magnitude and timing due to long term effects of the Martian Year 34 Global Dust Storm. We provide a rough estimate of projected hydrogen escape of 3.2 × 109 cm−2 s−1 associated to these plumes, adding further evidence of the key role played by the perihelion season in the long term evolution of the planet's climate.
Water vapor latitudinal variation during Ls1 = 240°–260° (a1, b1, c1), Ls2 = 260°–280° (a2, b2, c2), and Ls3 = 280°–300° (a3, b3, c3) for Martian Years (MYs) 34 (left), 35 (middle), and 36 (right). Lines show VMR contours at 100 (black), 50 (gray), and 20 (white) ppmv. Dots in panels a1–a3, b1–b3, c1–c3 indicate the latitude, Solar Longitude, and Local Solar Time of the observations. Panel (d) shows the seasonal variation of water vapor number density (cm−3) in the southern hemisphere at 100 km for Ls = 240°–300° during MYs 34 (blue), 35 (orange), and 36 (green). Vertical dashed line indicates the peak of the plume observed at 100 km during MYs 35 and 36 at Ls = 268°. Solid lines show the seasonal average. Panel (e) shows the latitude of the analyzed Nadir and Occultation for MArs Discovery Solar occultation observations over solar longitude for MYs 34 (blue), 35 (orange), and 36 (green). Horizontal dashed line indicates the equator. In panels (d) and (e), morning and evening terminator occultations are indicated with circles and triangles respectively.
