arXiv subjects

Jorge Hernández-Bernal

Publications and source records attributed to Jorge Hernández-Bernal.

4 recordsLinked to original sources

arXiv2026

Quasi-diurnal Kelvin Wave Observed in the Atmosphere of Mars by the Pressure Sensor on the InSight Lander

During the initiation phase of Martian dust storms, a spectral signature of a zonal wavenumber 1 normal mode Kelvin wave (K1) has been observed in several surface pressure records. However, the K1 signal has not been extracted directly since its eigenfrequency is close to that of the diurnal tide, making their separation difficult. We apply singular spectrum analysis to more than one Martian year of InSight surface pressure observations, including the MY34 C dust storm (C34). This analysis enables us to directly extract the transient K1 signal. Clear K1 signals appear during the Northern-Hemisphere spring and autumn with the average amplitudes of around 2 Pa. They reach 8 Pa during the C34 storm, which is substantial compared with a simultaneous diurnal signal (S1) maximum of 39 Pa. Near the peak time, K1 and S1 are in phase, and unexpectedly the S1 period shortens to 23.5 Mars hours. Subsequently, K1 rapidly decays and the S1 period recovers to 24 Mars hours. The phase relation between K1 and S1 as well as the S1 period shortening indicates that a resonance occurred between S1 and K1. Comparison with simulations at the model grid point closest to the InSight landing site shows that the Mars Planetary Climate Model realistically reproduces the observed characteristics of the surface pressure variations.

astro-ph.EP↗

arXiv2024

The Visual Monitoring Camera (VMC) on Mars Express: a new science instrument made from an old webcam orbiting Mars

The Visual Monitoring Camera (VMC) is a small imaging instrument onboard Mars Express with a field of view of ~40x30 degrees. The camera was initially intended to provide visual confirmation of the separation of the Beagle 2 lander and has similar technical specifications to a typical webcam of the 2000s. In 2007, a few years after the end of its original mission, VMC was turned on again to obtain full-disk images of Mars to be used for outreach purposes. As VMC obtained more images, the scientific potential of the camera became evident, and in 2018 the camera was given an upgraded status of a new scientific instrument, with science goals in the field of Martian atmosphere meteorology. The wide Field of View of the camera combined with the orbit of Mars Express enable the acquisition of full-disk images of the planet showing different local times, which for a long time has been rare among orbital missions around Mars. The small data volume of images also allows videos that show the atmospheric dynamics of dust and cloud systems to be obtained. This paper is intended to be the new reference paper for VMC as a scientific instrument, and thus provides an overview of the updated procedures to plan, command and execute science observations of the Martian atmosphere. These observations produce valuable science data that is calibrated and distributed to the community for scientific use.

astro-ph.IM↗

arXiv2024

An Extremely Elongated Cloud over Arsia Mons Volcano on Mars: II. Mesoscale modeling

In a previous work (Hernández-Bernal et al. 2021) we performed an observational analysis of the Arsia Mons Elongated Cloud (AMEC), which stands out due to its impressive size and shape, quick dynamics, and the fact that it happens during the martian dusty season. Observations show that its morphology can be split in a head, on the western slope of the volcano of around 120 km in diameter; and a tail, that expands to the west reaching more than 1000 km in length, making the AMEC the longest orographic cloud observed so far in the solar system. In this work we run the LMD (Laboratoire de Météorologie Dynamique) Mesoscale Model to gain insight into the physics of the AMEC. We note that it is coincident in terms of local time and seasonality with the fastest winds on the summit of Arsia Mons. A downslope windstorm on the western slope is followed by a hydraulic-like jump triggering a strong vertical updraft that propagates upwards in the atmosphere, causing a drop in temperatures of down to 30K at 40-50 km in altitude, spatially and temporarily coincident with the observed head of the AMEC. However the model does not reproduce the microphysics of this cloud: the optical depth is too low and the expansion of the tail does not happen in the model. The observed diurnal cycle is correctly captured by the model for the head of the cloud. This work raises new questions that will guide future observations of the AMEC.

astro-ph.EP↗

arXiv2019

The onset and growth of the 2018 Martian Global Dust Storm

We analyze the onset and initial expansion of the 2018 Martian Global Dust Storm (GDS 2018) using ground-based images in the visual range. This is the first case of a confirmed GDS initiating in the Northern Hemisphere. A dusty area extending about 1.4x10e5 km^2 and centered at latitude +31.7° $\pm$ 1.8° and west longitude 18° $\pm$ 5°W in Acidalia Planitia was captured on 30 and 31 May 2018 (Ls = 184.9°). From 1 to 8 June, daily image series showed the storm expanding southwards along the Acidalia corridor with velocities of 5 m/s, and simultaneously progressing eastwards and westwards with horizontal velocities ranging from 5 to 40 m/s. By 8 June the dust reached latitude -55° and later penetrated in the South polar region, whereas in the North the dust progression stopped at latitude +46°. We compare the onset and expansion stage of this GDS with the previous confirmed storms.

astro-ph.EP↗