Proyecto de Investigación: CONTRIBUCION DEL CAB+INTA
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PID2019-107061GB-C61
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A Study of Daytime Convective Vortices and Turbulence in the Martian Planetary Boundary Layer Based on Half-a-Year of InSight Atmospheric Measurements and Large-Eddy Simulations
(American Geophysical Union: Advancing Earth and Space Science, 2021-01-12) Spiga, A.; Murdoch, N.; Lorenz, R.; Forget, F.; Newman, C. E.; Rodríguez, Sébastien; Pla García, J.; Viúdez Moreiras, Daniel; Banfield, D.; Perrin, C.; Mueller, N. T.; Lemmon, M. T.; Millour, E.; Banerdt, W. B.; Agencia Estatal de Investigación (AEI); Spiga, A. [0000-0002-6776-6268]; Murdoch, N. [0000-0002-9701-4075]; Lorenz, R. [0000-0001-8528-4644]; Forget, F. [0000-0002-3262-4366]; Newman, C. [0000-0001-9990-8817]; Rodríguez, S. [0000-0003-1219-0641]; Pla García, J. [0000-0002-8047-3937]; Viúdez Moreiras, D. [0000-0001-8442-3788]; Perrin, C. [0000-0002-7200-5682]; Mueller, N. T. [0000-0001-9229-8921]; Lemmon, M. [0000-0002-4504-5136]; Millour, E. [0000-0003-4808-9203]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Studying the atmospheric planetary boundary layer (PBL) is crucial to understand the climate of a planet. The meteorological measurements by the instruments onboard InSight at a latitude of 4.5°N make a unique rich data set to study the active turbulent dynamics of the daytime PBL on Mars. Here we use the high-sensitivity continuous pressure, wind, and temperature measurements in the first 400 sols of InSight operations (from northern late winter to midsummer) to analyze wind gusts, convective cells, and vortices in Mars’ daytime PBL. We compare InSight measurements to turbulence-resolving large-eddy simulations (LES). The daytime PBL turbulence at the InSight landing site is very active, with clearly identified signatures of convective cells and a vast population of 6,000 recorded vortex encounters, adequately represented by a power law with a 3.4 exponent. While the daily variability of vortex encounters at InSight can be explained by the statistical nature of turbulence, the seasonal variability is positively correlated with ambient wind speed, which is supported by LES. However, wind gustiness is positively correlated to surface temperature rather than ambient wind speed and sensible heat flux, confirming the radiative control of the daytime Martian PBL; and fewer convective vortices are forming in LES when the background wind is doubled. Thus, the long-term seasonal variability of vortex encounters at the InSight landing site is mainly controlled by the advection of convective vortices by ambient wind speed. Typical tracks followed by vortices forming in the LES show a similar distribution in direction and length as orbital imagery.
Is the Bremer Deep Field reionized, at z ∼ 7?
(Oxford Academics: Oxford University Press, 2021-03-01) Rodríguez Espinosa, J. M.; Mas-Hesse, J. Miguel; Calvi, R.; Agencia Estatal de Investigación (AEI); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We show herein that the population of star-forming galaxies in the Bremer Deep Field (BDF) has enough ionizing power to form two large ionized bubbles that could be in the process of merging into a large one with a volume of 14 000 cMpc3. The sources identified in the BDF have been completed with a set of expected low-luminosity sources at z ∼ 7. We have estimated the number of ionizing photons per second produced by the different star-forming galaxies in the BDF. This number has been compared with the number that would be required to ionize the bubbles around the two overdense regions. We have used, as reference, ionizing emissivities derived from the AMIGA (Analytic Model of Intergalactic-medium and Galaxies) cosmological evolutionary model. We find that even using the most conservative estimates, with a Lyman continuum escape fraction of 10 per cent, the two regions we have defined within the BDF would be reionized. Assuming more realistic estimates of the ionizing photon production efficiency, both bubbles would be in the process of merging into a large reionized bubble, such as those that through percolation completed the reionization of the Universe by z = 6. The rather small values of the escape fraction required to reionize the BDF are compatible with the low fraction of faint Ly α emitters identified in the BDF. Finally, we confirm that the low-luminosity sources represent indeed the main contributors to the BDF ionizing photon production.
