Examinando por Autor "Gebhardt, C."

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Acceso Abierto
Characterizing Dust-Radiation Feedback and Refining the Horizontal Resolution of the MarsWRF Model Down to 0.5 Degree
(American Geophysical Union: Advancing Earth and Space Science, 2021-02-19) Gebhardt, C.; Abuelgasim, A.; Fonseca, R. M.; Martín Torres, Javier; Zorzano, María Paz; United Arab Emirates University (UAE University); Agencia Estatal de Investigación (AEI); Gebhardt, C. [0000-0003-4811-6267]; Abuelgasim, A. [0000-0001-8897-4181]; Fonseca, R. [0000-0002-8562-7368]; Zorzano, M. P. [0000-0002-4492-9650]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
In this study, three simulations by the Mars Weather Research and Forecasting Model are compared: two 10 Martian year (MY) 2° × 2° simulations with (i) fully radiatively active dust and (ii) a prescribed dust scenario, and a (iii) 1 MY 0.5° × 0.5° simulation with prescribed dust as in (ii). From comparing (i) and (ii), we found that the impact of dust-radiation feedback is individually different for any region. The most striking evidence are major dust lifting activities to the south of Chryse Planitia (S-CP) seen in (i) but not in (ii). By contrast, dust lifting and deposition on the southern slopes and inside the Hellas Basin are similar in both simulations. The latter, in turn, points toward a similar near-surface atmospheric circulation. In (iii), the total global amount of wind stress lifted dust is by a factor of ∼8 higher than in (ii), with S-CP being a major lifting region as in (i). Nonetheless, the surface dust lifting by wind stress in (iii) may be also reduced regionally, as seen at the peak of Elysium Mons because of its unique topography. The zonal mean circulation in (i) is generally of a comparable strength to that in (ii), with exceptions in global dust storm years, when it is clearly stronger in (i), in line with a dustier atmosphere. The differences in the zonal mean circulation between (ii) and (iii) are mostly at lower altitudes and may arise because of differences in the representation of the topography.
Acceso Abierto
Fully Interactive and Refined Resolution Simulations of the Martian Dust Cycle by the MarsWRF Model
(American Geophysical Union, 2020-08-25) Gebhardt, C.; Abuelgasim, A.; Fonseca, R. M.; Martín Torres, Javier; Zorzano, María Paz; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The MarsWRF model is set up with fully interactive dust at 5° × 5° and 2° × 2 resolution. The latter allows for a better representation of topography and other surface properties. An infinite reservoir of surface dust is assumed for both resolutions. For 5° × 5°, surface dust lifting by wind stress takes place over broad areas, occurring in about 20% of the model's grid cells. For 2° × 2°, it is more spatially restricted, occurring in less than 5% of the grid cells, and somewhat reminiscent of the corridors Acidalia‐Chryse, Utopia‐Isidis, and Arcadia‐West of Tharsis. The onset times of major dust storms—large regional storms or global dust storm events (GDEs)—do not exhibit much interannual variability, typically occurring at around Ls 260°. However, their magnitude does show significant interannual variability—with only small regional storms in some years, large regional storms in others, and some years with GDEs—owing to the interaction between major dust lifting regions at low latitudes. The latter is consistent with observed GDEs having several active dust lifting centers. The agreement between the model's surface dust distribution and observation‐based dust cover index maps is potentially better for 2° × 2°. For the latter, there is also significant surface dust lifting by wind stress in the aphelion season that is largely confined to the Hellas basin. It has a recurring time pattern of 2–7 sols, possibly resulting from the interaction between midlatitude baroclinic systems and local downslope flows.