التفاصيل البيبلوغرافية
| العنوان: |
Seasonal Variations in Airflow Over the Namib Dune, Gale Crater, Mars: Implications for Dune Dynamics. |
| المؤلفون: |
Cornwall, Carin, Jackson, Derek W. T., Cooper, J. Andrew G., Bourke, Mary C., Beyers, Meiring |
| المصدر: |
Geophysical Research Letters; 9/28/2018, Vol. 45 Issue 18, p9498-9507, 10p |
| مصطلحات موضوعية: |
GALE Crater (Mars), ERGS (Landforms), MARTIAN atmosphere, AIR flow |
| الشركة/الكيان: |
CURIOSITY (Spacecraft) |
| مستخلص: |
Dune length scale airflow modeling provides new insights on eolian bedform response and complex near‐surface 3‐D wind patterns not previously resolved by mesoscale models. At a 1‐m surface resolution, Curiosity wind data are used to investigate the eolian environment of the Namib dune on Mars, providing improved seasonal constraints on grainfall, grainflow activity, and ripple migration. Based on satellite images, airflow patterns, and surface shear stress, enhanced eolian activity, and slipface advancement occurs during early springtime. Autumn and winter winds are also favorable to eolian activity, but minimal movement was detected in satellite images overlapping with wind data. During the summer, the migration of large stoss ripples on the Namib dune may augment sediment deposition on the slipface. These results provide a better understanding of the overall migration pattern of the Namib dune, which can be extrapolated to other dunes in the Bagnold Dune Field. Plain Language Summary: At 1‐m resolution, small‐scale airflow modeling can provide new insights into sediment transport and dune migration on Mars. Coupled with wind data collected by the Curiosity rover, this study provides improved, realistic constraints on Martian sediment movement and illustrates how ripples seasonally form and migrate according to changing wind speeds and directions. The spring season with northerly winds is the most influential for dune migration based on modeling results and satellite monitoring, but the quieter summer and autumn seasons with southeasterly winds continue to facilitate ripple migration, which may help maintain slower rates of dune migration despite the opposing wind direction. Based on modeling results, the winter season with high‐magnitude northerly winds should produce migration rates similar to spring, but according to satellite monitoring, dune migration stops. Small amounts of frost in between sand grains on the dune surface may be responsible for this halt in dune migration. These results can be applied to other dunes in the Bagnold Dune Field, which likely experience the same seasonal patterns in sediment transport. Key Points: CFD data provide a more complete understanding of Martian sediment transport, augmenting ripple mapping studiesDune length scale modeling highlights areas of elevated surface shear stress that affect localized sediment fluxDetailed seasonal 3‐D airflow structures are presented that have not been previously attainable using mesoscale models [ABSTRACT FROM AUTHOR] |
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