Examinando por Autor "Toledo, D."

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Acceso Abierto
Convective Vortices and Dust Devils Detected and Characterized by Mars 2020
(AGU Advancing Earth and Space Science, 2023-02-10) Hueso, R.; Newman, C. E.; Del Río Gaztelurrutia, T.; Munguira, A.; Sánchez Lavega, Agustín; Toledo, D. ; Apéstigue, Víctor; Arruego, Ignacio; Vicente Retortillo, Álvaro; Martínez, Germán M.; Lemmon, M. T.; Lorenz, Ralph; Richardson, M. I.; Viúdez Moreiras, Daniel; De la Torre Juárez, M.; Rodríguez Manfredi, J. A.; Tamppari, L. K.; Murdoch, N.; Navarro López, Sara; Gómez Elvira, J.; Baker, M.; Pla García, J.; Harri, Ari-Matti; Hieta, M.; Genzer, María; Polkko, J.; Jaakonaho, I.; Makinen, Terhi; Stott, Alexander; Mimoun, D.; Chide, B.; Sebastián Martínez, Eduardo; Banfield, D.; Lepinette Malvitte, A.; Gobierno Vasco; Ministerio de Ciencia e Innovación (MICINN); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Los Alamos National Laboratory (LANL); Arizona State University (ASU); Universities Space Research Association (USRA); NASA Jet Propulsion Laboratory (JPL); Comunidad de Madrid; Academy of Finland (AKA); Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
We characterize vortex and dust devils (DDs) at Jezero from pressure and winds obtained with the Mars Environmental Dynamics Analyzer (MEDA) instrument on Mars 2020 over 415 Martian days (sols) (Ls = 6°–213°). Vortices are abundant (4.9 per sol with pressure drops >0.5 Pa correcting from gaps in coverage) and they peak at noon. At least one in every five vortices carries dust, and 75% of all vortices with Δp > 2.0 Pa are dusty. Seasonal variability was small but DDs were abundant during a dust storm (Ls = 152°–156°). Vortices are more frequent and intense over terrains with lower thermal inertia favoring high daytime surface-to-air temperature gradients. We fit measurements of winds and pressure during DD encounters to models of vortices. We obtain vortex diameters that range from 5 to 135 m with a mean of 20 m, and from the frequency of close encounters we estimate a DD activity of 2.0–3.0 DDs km−2 sol−1. A comparison of MEDA observations with a Large Eddy Simulation of Jezero at Ls = 45° produces a similar result. Three 100-m size DDs passed within 30 m of the rover from what we estimate that the activity of DDs with diameters >100 m is 0.1 DDs km−2sol−1, implying that dust lifting is dominated by the largest vortices in Jezero. At least one vortex had a central pressure drop of 9.0 Pa and internal winds of 25 ms−1. The MEDA wind sensors were partially damaged during two DD encounters whose characteristics we elaborate in detail.
Acceso Abierto
Detection of visible-wavelength aurora on Mars
(Science, 2025-05-14) Knutsen, Elise; McConnochie, Timothy; Lemmon, M. T.; Donaldson, Chris; Francis, Raymond; Legett, Carey; Viet, Shayla; Soret, Lauriane; Toledo, D.; Apéstigue, Víctor; Witasse, Olivier; Montmessin, F.; Jolitz, Rebecca; Schneider, Nicolas; Tamppari, L. K.; Cousin, Agnes; Wiens, Roger; Maurice, Sylvestre; Bell, James; Forni, Olivier; Lasue, Jeremie; Pilleri, Paolo; Bertrand, Tanguy; Patel, Priya; Schröder, Susanne; Curry, Shannon; Lee, Christina; Rahmati, Ali; National Aeronautics and Space Administration (NASA); Belgian National Fund for Scientific Research; Jet Propulsion Laboratory; Norges Forskningsråd
Mars hosts various auroral processes despite the planet’s tenuous atmosphere and lack of a global magnetic field. To date, all aurora observations have been at ultraviolet wavelengths from orbit. We describe the discovery of green visible-wavelength aurora, originating from the atomic oxygen line at 557.7 nanometers, detected with the SuperCam and Mastcam-Z instruments on the Mars 2020 Perseverance rover. Near–real-time simulations of a Mars-directed coronal mass ejection (CME) provided sufficient lead-time to schedule an observation with the rover. The emission was observed 3 days after the CME eruption, suggesting that the aurora was induced by particles accelerated by the moving shock front. To our knowledge, detection of aurora from a planetary surface other than Earth has never been reported, nor has visible aurora been observed at Mars. This detection demonstrates that auroral forecasting at Mars is possible, and that during events with higher particle precipitation, or under less dusty atmospheric conditions, aurorae will be visible to future astronauts.
Acceso Abierto
Methane precipitation in ice giant atmospheres
(EDP Sciences, 2025-02-04) Toledo, D. ; Rannou, P.; Irwin, P.; De Batz de Trenquelléon, B.; Roman, Michael , M.; Apéstigue, Víctor; Arruego, Ignacio; Yela González, Margarita; Agencia Estatal de Investigación (AEI)
Context. Voyager-2 radio occultation measurements have revealed changes in the atmospheric refractivity within a 2–4 km layer near the 1.2-bar level in Uranus and the 1.6-bar level in Neptune. These changes were attributed to the presence of a methane cloud, consistent with the observation that methane concentration decreases with altitude above these levels, closely following the saturation vapor pressure. However, no clear spectral signatures of such a cloud have been detected thus far in the spectra acquired from both planets. Aims. We examine methane cloud properties in the atmospheres of the ice giants, including vertical ice distribution, droplet radius, precipitation rates, timescales, and total opacity, employing microphysical simulations under different scenarios. Methods. We used a one-dimensional (1D) cloud microphysical model to simulate the formation of methane clouds in the ice giants. The simulations include the processes of nucleation, condensation, coagulation, evaporation, and precipitation, with vertical mixing simulated using an eddy-diffusion profile (Keddy). Results. Our simulations show cloud bases close to 1.24 bars in Uranus and 1.64 bars in Neptune, with droplets up to 100 µm causing high settling velocities and precipitation rates (∼370 mm per Earth year). The high settling velocities limit the total cloud opacity, yielding values at 0.8 µm of ∼0.19 for Uranus and ∼0.35 for Neptune, using Keddy = 0.5 m2 s−1 and a deep methane mole fraction (μCH4) of 0.04. In addition, lower Keddy or μCH4 values result in smaller opacities. Methane supersaturation is promptly removed by condensation, controlling the decline in μCH4 with altitude in the troposphere. However, the high settling velocities prevent the formation of a permanent thick cloud. Stratospheric hazes made of ethane or acetylene ice are expected to evaporate completely before reaching the methane condensation level. Since hazes are required for methane heterogeneous nucleation, this suggests either a change in the solid phase properties of the haze particles, inhibiting evaporation, or the presence of photochemical hazes.