---

Recorded video: YouTube, Bilibili

---

Abstract:

The ExoMars Trace Gas Orbiter (TGO) has been scanning the atmosphere of Mars for four years, providing unprecedented measurements of its composition and vertical structure. One of the primary objectives of the mission is to study the water cycle, linking the measurements in the lower and upper atmospheres to better understand the escape of water to space. Recently, measurements from the TGO allowed the first detection of HCl, providing key information about a new type of chemical cycle on Mars. Finally, measurements of the isotopic ratios in CO₂, H₂O and CO by the TGO allow the characterisation of fractionation sources in the atmosphere, relevant to better understand the long-term evolution of the atmosphere of Mars throughout history. In this seminar, we provide an overview of the ExoMars mission and report some of the latest results from the orbiter.

About the speaker:

Dr. Juan Alday is a Postdoctoral Researcher at The Open University, United Kingdom. He obtained his PhD at the University of Oxford in 2021 using isotopic measurements from the ACS instrument on the ExoMars Trace Gas Orbiter, for which he was awarded the Royal Astronomical Society Keith Runcorn Prize. His work focuses in understanding the dust, water and chemical cycles in the atmosphere of Mars, with a particular interest in understanding how these cycles influence its isotopic composition.

Audience in the world:

(image credit: timeanddate.com)

---

---

Recorded video: YouTube, Bilibili

---

Abstract:

Most global climate models (GCMs) project a strong stratospheric moistening during global warming. It is important to understand the mechanisms leading to the stratospheric humidity change and how significantly the humidity change influences the surface warming. In this talk, I will present our recent works to address these questions, including high-resolution modelling of the convective injection process and a GCM-based mechanism denial experiment to verify the warming effect of stratospheric moistening.

About the speaker:

Yi Huang is an Associate Professor in the Department of Atmospheric and Oceanic Sciences at McGill University, Canada. His research is focused on climate physics and atmospheric radiation. He obtained his Ph.D. at Princeton University in 2008 and was a Climate and Global Change Postdoctoral Fellow at Harvard University before he joined the faculty at McGill University in 2011.

Audience in the world:

(image credit: timeanddate.com)

---

---

Recorded video: YouTube, Bilibili

---

Abstract:

The Martian Planetary Boundary Layer (PBL) is the lowest 10 km of the atmosphere that is directly influenced by the surface forcing. The PBL is highly turbulent on Mars owing to high thermal contrasts, short radiative timescales, low atmospheric density and steep topographical gradients; leading to a strong vertical mixing in the atmosphere. The dust gets entrained into the PBL because of the turbulent mechanisms, and are transported by atmospheric winds to spatial scales from local to global. They can remain suspended for hours or days as the gravitational pull of Mars is low. This dust has important feedback on the climate of Mars and has a strong impact on the atmosphere’s thermal and dynamical state by absorbing incoming solar radiation and outgoing radiation from the surface. Thus, it is important to study the processes by which dust can enter into the atmosphere, for which convective vortices have been proposed as an efficient mechanism. The vortices in which winds and pressure drop are strong enough to pull dust from the surface into the atmosphere are called “dust devils”. But the quantitative contribution to the total dust loading in the atmosphere and relative dust loading within the dust devil, are not well understood. In this webinar I will discuss about the various characteristics of Martian dust devils, and their quantitative investigation. I will discuss about the in-situ meteorological data recorded by NASA’s Curiosity rover, to detect convective vortex events on Mars. We have detected several dust devils in Gale crater, by analyzing data from the Rover Environmental Monitoring Station (REMS), onboard the Curiosity rover during Martian Year 33. A seasonal variation of these events suggest that they are frequent during the local summer season, during which the pressure drop associated with the vortex events are also high compared to other seasons. We model the spatial distribution of dust concentration within a steady state Martian dust devil. Our simulations indicate a maximum concentration of particles near the surface and at the boundary of the vortex. Finally, I will also discuss about the generation of electric fields within the dust devils due to tribocharging of the dust particles.

About the speaker:

Dr. Shefali Uttam completed her Ph.D. in August 2021 from Physical Research Laboratory, India under the supervision of Prof. Varun Sheel. The title of her thesis is “An Investigation of Martian Dust Devil Characteristics” in which she has studied about convective vortex properties and characteristics using various analytical and numerical approaches. Her research interests include modeling of dust lifting activities and understanding the impact of local topography, surface properties and dynamics of PBL in the dust lifting and transportation using mesoscale models.

Audience in the world:

(image credit: timeanddate.com)

---

---

Recorded video: YouTube, Bilibili

---

Abstract:

Uranus and Neptune are 3-4 times larger than Earth and 15-17 more massive. They have rocky/icy compositions and are covered by extended hydrogen and helium atmospheres that comprise a 15-20% of their masses. The high abundances of volatiles makes the atmospheric dynamics observed at the upper visible clouds very different to what we observe in the upper clouds of the Gas Giants Jupiter and Saturn. Here I will review the main known characteristics of the atmosphere dynamics of Uranus and Neptune and I will show the major incognita. New sources of information will come soon from telescopes such as JWST and the 30-m class ground-based telescopes like ELT, and even large-base interferometry in radio and millimeter wavelengths able to peer down the tens of bars in the atmosphere. Ice Giants are among the most numerous exoplanets discovered so far. In our own solar system, Uranus and Neptune remain as the least explored planets and we lack essential data to understand them related to the atmospheric composition and vertical structure, atmospheric dynamics at high spatial resolution, internal structure and magnetospheres building a very compelling case for space missions to these planets.

About the speaker:

Ricardo Hueso is assistant professor at the University of the Basque Country in Spain. He obtained his Ph.D. in Physics in 2000 studying moist convection in the atmospheres of Jupiter and Saturn. He later made a post-doc stay at the Observatory of Nice in France (2001-2002) where he worked on protoplanetary disks and planet formation. After his return to the University of the Basque Country, his research interests expanded to now involve dynamical aspects of the atmospheres of solar system planets from Venus to Neptune. Dr. Hueso has participated in several space missions like Venus Express, Mars Express, Mars 2020 or JUICE (ESA’s new mission to the Jupiter System with a launch in 2023) doing multi-disciplanary studies of these atmospheres and also collaborating with missions like Cassini or Juno. He also works with ground-based and space-based observations where he is well-known from his many collaborations with amateur astronomers.

Audience in the world:

(image credit: timeanddate.com)

---

---

Link to the Zoom webinar: https://us02web.zoom.us/j/88549245299?pwd=cTJrTG5Hb05rQS82ZDlXYmM1dTVXUT09

Webinar ID: 885 4924 5299, Passcode: 965315

---

Abstract:

Jupiter is the largest planet in the Solar System. It is composed of hydrogen and helium with heavier species such as water. Jupiter has undergone Kelvin-Helmholtz contraction with a shrinking rate of about 1 mm/year, radiating an internal energy flux to space much larger than the absorbed solar flux. It was believed that Jupiter’s internal heat was transported to the photosphere by vigorous thermal convection, in which warm air rises and cold air sinks. In this talk, I will show this traditional picture is not correct. We use cloud-resolving simulations to demonstrate that convective heat transport is significantly inhibited in the stably stratified region in Jupiter’s weather layer where water condenses. Instead, we argue that Jupiter’s atmosphere behaves like an air conditioner using water as the refrigerant. The active hydrologic cycle with water condensation and evaporation produces intermittent moist storms that transport the latent heat across the stable layer where the Bowen ratio (sensible to latent heat ratio) is close to zero. Our new theory represents paradigm-shift thinking of Jupiter. It explains the existence of the stable layer inside Jupiter as revealed by the comet impact in 1994 and active moist storm systems observed by the Galileo and Cassini spacecraft. It also depicts how the disjointed shallow and deep meteorological systems interact in Jupiter. This work further suggests why Jupiter’s interior is likely hotter than we thought and potentially reconciles the dilemma from the recent gravity measurement by the Juno spacecraft. Finally, I will talk about applying this framework to other planets, exoplanets, and brown dwarfs to understand their structure and evolution in the James Webb Space Telescope (JWST) era.

About the speaker:

Xi Zhang is an associate professor in the Department of Earth and Planetary Sciences at the University of California Santa Cruz. He got his bachelor’s degree in space science from Peking University in 2007 and received his Ph.D. in planetary sciences from the California Institute of Technology in 2013. He was a Bisgrove postdoctoral fellow at the University of Arizona before joining UC Santa Cruz in 2015. Xi’s research covers many topics in planetary atmospheres within and out of the Solar System. He was awarded the AGU Ronald Greeley Early Career Award in 2019.

Audience in the world:

(image credit: timeanddate.com)

---

---

Recorded video: YouTube, Bilibili

---

Abstract:

Close-in giant planets with strong stellar irradiation show atmospheric circulation patterns with strong equatorial jets and global-scale stationary waves. So far, almost all modeling works on atmospheric circulations of such giant planets have mainly considered external radiation alone, without taking into account the role of internal heat fluxes or just treating it in very simplified ways. Here, we study atmospheric circulations of strongly irradiated giant planets by considering the effect of internal forcing, which is characterized by small-scale stochastic interior thermal perturbations, using a three-dimensional atmospheric general circulation model. We show that the perturbation-excited waves can largely modify atmospheric circulation patterns in the presence of relatively strong internal forcing. Specifically, our simulations demonstrate three circulation regimes: a superrotation regime, a midlatitude-jet regime, and a quasi-periodic oscillation regime, depending on the relative importance of external and internal forcings. It is also found that strong internal forcing can cause noticeable modifications of the thermal phase curves.

About the speaker:

Yongyun Hu is a Professor in the Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University. He had served as the Department Chair the Vice Dean (2009-2019). He finished his BS at Sun Yat-sen University (1982-1986), MS at Texas A&M University, and PhD at the University of Chicago (1996-2000). He had worked as a Postdoctoral Research Associate at the University of Washington (2000-2002) and Columbia University (2002-2004). He has broad research interests in present, past, and planetary climates.

Audience in the world:

(image credit: timeanddate.com)

---

---

Recorded video: YouTube, Bilibili

---

Abstract:

Narrow-band, high-resolution spectroscopy has proven to be a powerful complementary technique to space-based observations and has provided the exoplanet community with various detected atmospheric signatures. Due to the detections of the line centre and wings, resolved lines such as sodium give us a valuable insight into the vertical structure of exoplanet atmospheres not accessible with low-resolution space-based missions. 

ESPRESSO, as the first high-resolution spectrograph of the 2020s, has brought a significant increase in line precision, as shown with the re-observation of WASP-76b (Tabernero et al. 2020) and WASP-121b (Borsa et al. 2021), allowing us to move beyond the sole observation of the sodium doublet to a plethora of resolved spectral lines and opening the first door into line shape interpretation.

The analysis of line shapes in ESPRESSO data permits us to retrieve wind patterns in the upper atmosphere, but additionally also gives us unprecedented observational insights into the lower atmosphere from the line wings (Seidel et al. 2021). In this talk I will provide the community with a guide what we can, and can’t derive about atmospheric winds in exoplanet atmospheres with the current data quality and what lies beyond the study of atmospheric winds: the derivation of exoplanet atmospheric field strength and the possible origins of the detected signals – volcanoes, debris disks, and exo-moons.

About the speaker:

Dr. Julia V. Seidel is a post-doctoral Fellow at the European Southern Observatory, mainly working at ESO’s Paranal Observatory, as well as one of ESO’s ESPRESSO Instrument Fellows. She has obtained her PhD at the University of Geneva in Switzerland on the study of exoplanet atmospheres. Her work focuses on the observation of atmospheric dynamics and the various applications of narrow-band, high-resolution spectroscopy. She additionally works on the study of terrestrial atmospheric conditions at telescope sites and various outreach projects geared towards Latin America.

Audience in the world:

(image credit: timeanddate.com)

---

---

Recorded video: YouTube, Bilibili

---

Abstract:

Polarisation is a little known property of light. Maybe because humans cannot really see it with their eyes, polarisation appears to have a hard time getting into our hearts and astronomical instrumentation. Direct light of the sun and sun-like stars is mostly unpolarised, i.e. the electromagnetic waves have no preferential vibrational direction, but when this unpolarised light is scattered by atmospheric particles and/or when it is reflected by a surface, it will usually become polarised. The state of polarisation of this light is very sensitive to the composition and structure of the atmosphere and/or the surface. Polarisation measurements have been shown to provide information that cannot not be retrieved from brightness measurements alone, such as the composition of the clouds of our neighbouring planet Venus. Polarimetry also promises to be a strong tool for the detection and characterisation of exoplanets, because it enhances the star-planet contrast, provides a direct confirmation of the planetary nature of the stellar companion, and could reveal information on the atmosphere and surface of the exoplanet.

Examples of the application of polarimetry for the characterisation of solar system planets and exoplanets will be provided, and SELFIE, a plan for a small spectropolarimeter that is designed to observe the Earth from afar, as if it were an exoplanet, will be introduced.

About the speaker:

Daphne Stam studied Theoretical Physics and Astronomy at the Vrije Universiteit in Amsterdam. Her PhD-research, on spectral variations in the polarisation of sunlight that is reflected by the Earth, was performed at the KNMI and the Vrije Universiteit, under the supervision of prof. Joop Hovenier. As a postdoctoral researcher at Cornell University, Daphne worked on the analysis of observations of clouds and hazes on Saturn, Uranus and Neptune. Back in the Netherlands, she trained for a year to become a Clinical Physicist at the Antoni van Leeuwenhoekziekenhuis, but missed planetary research too much and she returned with a prestigious Veni-grant to work on polarisation signals of exoplanets, planets around other stars, at the University of Amsterdam. With a Vidi-grant on the same topic, Daphne started a research group on Planetary and Exoplanetary research at SRON, the Netherlands Institute for Space Research, where she initiated with Leiden astronomers Frans Snik and Christoph Keller the development of SPEX, a small spectropolarimeter for planetary remote-sensing, which will be launched in 2024 onboard a NASA Earth observation mission. In 2012, Daphne took up a position at the rapidly expanding Planetary Exploration group of the faculty of Aerospace Engineering at the Technical University in Delft, where she is Associate Professor of Planetary Sciences, still working on variations of the SPEX instrument and other small polarimeters, and atmospheres of planets around the Sun and beyond. Daphne is co-I on ESA’s Envision mission to Venus.

Audience in the world:

(image credit: timeanddate.com)

---

---

---

Abstract:

Jupiter represents a class of planets whose major composition is hydrogen and helium, with a few condensable species forming visible clouds high up. Jovian atmospheres typically feature multiple zonal jets at the speed of hundreds of meters per second, and incessant popping of small-scale storms and vortices. The ongoing Juno mission has told us the depth of the zonal winds, the abundance of the water and the complex pattern of the swirling vortices in three-dimension. I will introduce the major findings of the Juno mission regarding Jupiter’s weather layer and discuss the role of atmospheric dynamics in shaping Jupiter’s structure and the observed composition.

About the speaker:

Dr. Li graduated from Peking University, School of Physics in 2011. After graduation, he went to Caltech for his Ph.D. He studied moist convection on giant planets and received his Ph.D. in 2017. Then he was awarded the NASA postdoc program fellow and stayed at JPL working on the Juno mission. His work at the Juno team is to infer Jupiter’s atmospheric structure using the Juno microwave radiometer. He is currently the Co-I of the Juno mission. In 2019, he switched to the 51 Peg b postdoc fellow at UC Berkeley supported by the Heising-Simons Foundation. He joined the University of Michigan as an assistant professor in 2021. He develops hydrodynamic code to simulate moist convection and spectral inversion algorithms to infer atmospheric conditions via remote sensing.

Audience in the world:

(image credit: timeanddate.com)

---

---

Recorded video: YouTube, Bilibili

---

Abstract:

The atmosphere of Venus is known for its harsh greenhouse effect, planet-wide sulfuric acid clouds, and fast westward winds. Apart from these planetary-scale structures, mesoscale processes, which are much smaller than the planet, might play crucial roles in the climate system. The complex cloud morphology observed in the ultraviolet wavelength region suggests that the Venusian atmosphere harbors a variety of mesoscale dynamics and associated cloud processes that are yet to be elucidated. JAXA’s Venus orbiter Akatsuki has been conducting continuous observations of the atmosphere using infrared and ultraviolet imaging and radio occultation, allowing investigation of mesoscale and planetary-scale processes and their interaction. In this talk, I will introduce the results of Akatsuki’s observations and their interpretations.

About the speaker:

Dr. Imamura is currently a professor at the University of Tokyo, Japan. After working on several space missions as a staff member at the Japan Aerospace Exploration Agency (JAXA), he moved to the university in 2016. His main expertise is the observation and modeling of planetary atmospheres, with an emphasis on Venusian atmospheric dynamics and cloud physics. He has also led the radio science in JAXA’s lunar mission Selene and Venus mission Akatsuki.

Audience in the world:

(image credit: timeanddate.com)

---