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Abstract It has been proposed that hot spot tracks are caused by moving rigid plates above relatively stationary hot spots. However, the fixity of hot spots remains under debate. Here, we perform 3‐D very high resolution (<25 km laterally) global mantle convection models with realistic convection vigor to investigate the lateral motion of mantle plumes. We find that the lateral motion of plumes beneath the Pacific plate is statistically similar to that beneath the Indo‐Atlantic plates. In the past 80 Ma, the majority (>90%) of plumes move laterally with an average speed of 0–20 mm/year under the no‐net‐rotation reference frame, and there are a small portion (~10–20%) of plumes whose lateral motion is less than 5 mm/year. The geodynamic modeling results are statistically in a good agreement with the hot spot motions in the last 5 Ma estimated from observation‐based kinematic models. Our results suggest a small‐to‐moderate (0–20 mm/year) lateral motion of most plume‐induced hot spots.
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Large Eddy Simulations of the Dusty Martian Convective Boundary Layer With MarsWRF
Abstract Large eddy simulation (LES) of the Martian convective boundary layer (CBL) with a Mars‐adapted version of the Weather Research and Forecasting model is used to examine the impact of aerosol dust radiative‐dynamical feedbacks on turbulent mixing. The LES is validated against spacecraft observations and prior modeling. To study dust redistribution by coherent dynamical structures within the CBL, two radiatively active dust distribution scenarios are used: one in which the dust distribution remains fixed and another in which dust is freely transported by CBL motions. In the fixed dust scenario, increasing atmospheric dust loading shades the surface from sunlight and weakens convection. However, a competing effect emerges in the free dust scenario, resulting from the lateral concentration of dust in updrafts. The resulting enhancement of dust radiative heating in upwelling plumes both generates horizontal thermal contrasts in the CBL and increases buoyancy production, jointly enhancing CBL convection. We define a dust inhomogeneity index (DII) to quantify how much dust is concentrated in upwelling plumes. If the DII is large enough, the destabilizing effect of lateral heating contrasts can exceed the stabilizing effect of surface shading such that the CBL depth increases with increasing dust optical depth. Thus, under certain combinations of total dust optical depth and the lateral inhomogeneity of dust, a positive feedback exists between dust optical depth, the vigor and depth of CBL mixing, and—to the extent that dust lifting is controlled by the depth and vigor of CBL mixing—the further lifting of dust from the surface.
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- Award ID(s):
- 1740921
- PAR ID:
- 10374583
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Planets
- Volume:
- 126
- Issue:
- 9
- ISSN:
- 2169-9097
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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