Wind and Waves on the Ocean Surfaces: Insights from the CFOSAT Mission with Danièle Hauser (IPSL, France)

The wind and ocean surface waves are key parameters affecting ocean / atmosphere exchanges, marine meteorology and upper layers of the ocean. More generally, sea-state parameters are essential variables of the climate system. They also have an impact on marine resources, off-shore economy and security, and coastal environments. To progress in the understanding of the ocean / atmosphere coupling, in its numerical modeling, as to further develop applications in oceanography, it is necessary to observe the wind and waves at a global scale. Altimeter satellite missions, in space since the 1990s, provide limited information on waves, while other satellite missions are dedicated to measuring winds over the global ocean. Since 2018, a new satellite called CFOSAT (China France Oceanography SATellite) is in orbit. Thanks to its original concept, it allows simultaneous description of wind and waves with details on ocean wave properties that were not previously accessible. This brings new perspectives to study ocean / atmosphere exchanges, improve wind and wave forecasting, study the impacts of climate change on the ocean surface. During this seminar, the spreaker will present a summary on wind and wave measurements from space and highlight the new contribution of the CFOSAT mission.

Danièle Hauser is a senior scientist with CNRS (Centre National de la Recherche Scientifique, France). She develops her research at LATMOS (Laboratoire Atmosphère Milieux Observations Spatiales), a laboratory funded by CNRS, by “Université de Versailles Saint-Quentin-en Yvelines” and by “Sorbonne University” and located in the Paris area (France).  She works on the physical processes taking place at the ocean surface, and more particularly on exchanges at the air/sea interface driven by wind and waves. She is an expert in developing new systems for ocean surface observations using remote sensing techniques. She is the Principal Investigator of the CFOSAT (China France Oceanography SATellite) mission which has been launched in 2018 and currently provides unique observations of surface wind and ocean waves. In recent years, she has also held various research management responsibilities, in particular she was director of LATMOS (2009-2013), as well as deputy scientific director at INSU (2014-2018).

Seminar was recorded on March 25, 2021

 

The Rossi X-ray Timing Explorer: Timing the Extreme Universe with Tomaso Belloni (INAF – Brera Astronomical Observatory, Italy)

The Rossi X-ray Timing Explorer (RXTE) was a satellite for X-ray astronomy launched by NASA on 30 December 1995 into a low-earth orbit. It operated for almost exactly sixteen years until its termination in January 2012. On board were three X-ray instruments a large-area Proportional Counter Array (PCA) built at NASA/GSFC, the High-Energy X-ray Timing Experiment (HEXTE) built at the University of California, San Diego, covering higher energies, an All-Sky Monitor (ASM), developed at MIT Cambridge.

Its characteristics, such as large collecting area, no imaging capability, high time resolution, broad energy coverage and very high flexibility of operation, together with the presence of an all-sky monitor to detect transient X-ray events, were aimed at the detailed study of bright galactic X-ray sources, in particular regarding their fast time variability. RXTE was indeed a giant step forward in our knowledge of variability of systems containing compact objects, the most powerful emitters of X-rays in our Galaxy and it allowed us to link their properties to physical models for accretion and to effects of General Relativity (GR) in the vicinity of a black hole or neutron star.

This was done through the discovery of millisecond quasi-periodic variability from accreting neutron stars in low-mass X-ray binaries, together with more elusive and slightly slower signals from black-hole binaries. These oscillations allowed us for the first time to obtain precise measurements of time scales in the accretion matter very close to a compact object, where the effects of GR are more extreme. Indeed, models based on GR frequencies have soon emerged and, although they have not been completely established, hold the promise to test GR in the strong field regime.

The long-sought missing link of neutron-star evolution was finally unveiled by RXTE: millisecond pulsations from accreting neutron stars in low-mass X-ray binaries. These systems were thought to be the progenitors of millisecond pulsars, but no pulsation was found and therefore we had no direct indication of their fast spinning. RXTE detected pulsations from several faint transient systems and sporadic pulsation from others. At the same time, evidences for neutron star rotation periods came from short-lived oscillations during nuclear explosions on the surface of the accreting neutron star. These provide powerful tools for studying properties of the compact object itself and have opened a promising avenue for putting tight constraints on the equation of state of neutron matter.

Sixteen years of operation mean a large discovery space: from the evolution of black-hole transients, to the discovery of extreme variability from peculiar objects, which can be linked to the complex phenomenon of ejection of relativistic collimated jets, to the long-term monitoring of the X-ray emission of active galactic nuclei and to the observation of signals from seismic waves on neutron stars in the case of an extremely powerful yet very rare flare. RXTE has changed our way we see accreting compact objects and has led the way to the current missions like NICER and Astrosat up to the future observatories like eXTP.

Tomaso Belloni is Research Executive at INAF – Brera Astronomical Observatory in Merate, Italy and Visiting Professor at the University of Southampton, UK. Although not directly involved in the mission, he has worked with RXTE data since its launch and continues today with the exploitation of its database, being also involved in the current Indian X-ray satellite Astrosat and the planning of the future mission eXTP. He is chair of COSPAR Commission E and vice-president of the Scientific Advisory Panel of INAF. His main research interests are in fast time variability from X-ray binaries, in particular black-hole binaries, and the search for GR effects through timing analysis.

Seminar was recorded on March 18, 2021

The Apollo Lunar Exploration Program: How Increasing Science Capabilities Resulted in a Revolutionary New View of the Moon with Jim Head (Brown University, Providence, Rhode Island, USA)

There has been hardly any other mission or mission program that has more fundamentally changed our way of understanding space than the Apollo Lunar Exploration Program. The first human landing on an extraterrestrial body, the first in-situ study by a trained geologist. The first sample return, the first extraterrestrial seismic experiment and network, the first extraterrestrial heat flow measurement, and, with particular reference to the University of Bern and ISSI, the first in-situ collection of solar wind particles, to name a few. Johannes Geiss founding father of the institute and at the time professor at the University of Bern had conceived of and built this simple and effective sensor that was the first scientific instrument installed on an extraterrestrial surface by a human being, soon after the landing of Apollo 11.   

Project Apollo landed six lunar modules and twelve astronauts between July 1969 and December 1972. It returned 382 kg of lunar samples and a wealth of data that are still explored to date. As examples we note that only a few years ago application of modern seismic data analysis tools to the historic Apollo seismograms have revealed what are arguably reflections of waves from the lunar core. Moreover, traces of water have recently been found in re-analysis of lunar samples.

In this presentation we discuss how the scientific input and science and engineering synergism during the Apollo Lunar Exploration Program resulted in ever-increasing capabilities to visit a wide range of landing sites on the Moon and to conduct geological traverses that culminated in the Apollo 15-16-17 Scientific Expeditions to the Moon. The Apollo Exploration program resulted in an entirely new paradigm for the origin and evolution of the Moon, and indeed, other planets.  Lessons for future human and robotic exploration will be described.

James W. Head is the Louis and Elizabeth Scherck Distinguished Professor of Geological Sciences at Brown University. He worked for the NASA Apollo program, in which he analyzed potential landing sites, studied returned lunar samples and data, and provided training for the Apollo astronauts. He studies processes that form and modify the surfaces, crusts and lithospheres of planets, how these processes vary with time, and how such processes interact to produce the historical record preserved on the planets. Comparative planetology, the themes of planetary evolution, and application of these to the study of early Earth history are also of interest.  Prof. Head received the Penrose Medal in 2015 as well as G.K. Gilbert Award. He is a Fellow of the American Association for the Advancement of Science, the Geological Society of America, and of the American Geophysical Union. He is a Dr. honoris causa of the Washington and Lee University. The Head Mountains in Antartica bear his name since 2007. Prof. Head has been a co-investigator on numerous NASA, ESA, Soviet and Russian missions, Including the Lunar Reconnaissance Orbiter and the European Space Agency’s Mars Express Mission

Seminar was recorded on March 11, 2021

In Search for the Exit from the Heliosphere: The Odyssey of Voyagers 1&2 Interstellar Missions (1977-2021) with Stamatios Krimigis

When the Voyager spacecraft were launched in 1977, the objective was to explore Jupiter and Saturn over the ensuing four years. At that time, estimates of the radial extent of the solar system were as small as 5 astronomical units (1 AU= 150 million km=the Sun-Earth distance). The Voyager science team, however, was fully aware of the unique arrangement of the outer planets that occurs every 175 years, enabling successive exploration of each planet through gravitational assists at each one. The endurance of the Voyager spacecraft provided the opportunity to not only explore Uranus and Neptune, in addition to Jupiter and Saturn, but also to initiate the Voyager Interstellar Mission, in search of the boundary between our solar system and the local interstellar medium (LISM). It was a long wait, since the Neptune encounter at 30 AU took place in 1989, but the heliopause was crossed some 23 years later by Voyager 1 in 2012 at 121.6 AU. The speaker has been a Voyager Principal Investigator since 1971, and will describe this remarkable journey, a modern Odyssey of the space era.

Stamatios Krimigis is Emeritus Head of the Space Exploration Sector of the Johns Hopkins Applied Physics Laboratory (APL), Counselor on Space to the Minister of Digital Governance of Greece, serves as Chairman of the National Committee for Space Research at the Academy of Athens, is Principal Investigator (PI) on NASA’s Voyagers 1, 2, and PI Emeritus on the Cassini-Huygens mission to Saturn, among others. He received B. Phys. from the University of Minnesota (1961), his Ph.D in Physics from the University of Iowa (1965) under J.A. Van Allen, served on the faculty, moved to APL in 1968, became Chief Scientist (1980), Space Department Head (1991) and Emeritus in 2004. He has built and/or participated in instruments that have flown to all nine classical planets beginning with Mariner 4 to Mars in 1965, ending with New Horizons to Pluto in 2015, and culminating with the Parker Solar Probe to the Sun launched in 2018. He has published over 630 papers in peer-reviewed journals and books with over 23,000 citations. He is a three-time recipient (1981, 1986, 2014) of NASA’s Exceptional Scientific Achievement Medal. In 1999 the International Astronomical Unionnamed asteroid 1979 UH as 8323 Krimigis. He is a Fellow of the American Physical Society (APS), the American Geophysical Union (AGU), the American Association for the Advancement of Science(AAAS) and the American Institute of Aeronautics and Astronautics (AIAA). More recent awards include the Council of European Aerospace Societies CEAS Gold Medal in 2011, the European Geophysical Union Jean Dominique  Cassini Medal (2014), the AIAA Van Allen Space Environments Award (2014), the National Air and Space Museum (NASM) Trophy for Lifetime Achievement (2015), the International Academy of Astronautics (IAA) Laurels Award for the MESSENGER Team (2015), the American Astronautical Society Space Flight Award, the NASM Trophy for Current Achievement (New Horizons Team), and the NASA Distinguished Public Service Medal, all in 2016, and the IAA Theodore von Karman Award (2017). He is a member of Academia Europaea, and was honored by a special resolution of the U. S. Senate “for exceptional contributions to space science” (2018).

Seminar was recorded on March 4, 2021

 

ISSI Game Changer Online Seminar: News from the ISSI Team

Dear Friends of ISSI and the ISSI Game Changer Online Seminar!
 
The first season of the ISSI Game Changer Seminar Series “How missions change(d) our view of the Solar System, the Universe, and the Earth” ends with the end of this month of March. 

In four blocks since July 2020, we first covered missions such as Rosetta, Hayabusa II, and SOHO to solar system objects, and then astrophysical space telescopes such as Gaia, Integral, and the Hubble Space Telecope. In 2021 to date, we presented Earth observation missions such as SMOS, Cryosat and GRACE. The series will conclude on March 25 with a presentation on CFOSAT, a joint Chinese and French oceanography mission to understand ocean dynamics and climate variability. 

Before that, however, we present three more highlights: First, this Thursday, March 4, Prof. Stamatios Krimigis will report on the space odyssey of the two Voyager probes, which have now left the solar system and are cruising in interstellar space!  This will be followed on March 11 by a talk on the Apollo program and its scientific legacy presented by Prof. Jim Head a witness to the first manned landing on an extraterrestrial body. For March 18, we are soliciting a talk on an x-ray astrophysics mission. 

The Game Changers seminars will then take a break in April. In May we plan to resume the series. But this time the focus will not be on missions but rather on themes, “Ideas and Findings about the Solar System, the Universe and our Terrestrial Environment”, as we plan to call it. 

Foreseen are talks on topics like the origin of the Moon and of the Solar System, comparing it to other planetary systems. Spectroscopy of extrasolar planetary atmospheres will be on our agenda as well as Martian Seismology, the composition of the Sun, space weather and astrobiology. We will further look at the latest on the Hubble constant controversy, present new results on the merger history of the Milky Way, and offer exiting views on supermassive black holes – in our Galaxy and elsewhere. For our terrestrial environment we will keep an eye on problems related to climate and global change and their societal impact but also compare the Earth to its siblings in the solar system.  
 
We plan not to proceed in blocks this time but rather mix themes. An astrophysical topic can therefore immediately follow an environmental topic and precede a planetary topic.  

While in our present program we have been looking back at those missions that helped us better understand our world, for the new series we dare to look ahead to topics that we consider to be particularly promising for the future.
 
With our best regards and stay safe & tuned

Your ISSI Team 

Weight-Watching from Space – Tracking Changes in Earth’s Surface Water with GRACE & GRACE-FO with Felix Landerer (JPL, USA)

Earth’s distribution of water – in the form of ice, snow, soil moisture, groundwater, as well as lake and sea levels – is undergoing profound changes as the climate changes over seasons to decades. The original Gravity Recovery and Climate Experiment (GRACE) mission, launched in early 2002, has provided a unique and valuable data record to monitor and study changes in our global water cycle, and allowed precise determination of sea-level rise, polar ice-cap mass loss in Greenland and Antarctica, and large-scale water storage changes over land. By measuring small month-to-month changes in Earth’s gravity field, these observations provide a unique window into Earth’s evolving climate and water stores, and a glimpse into possible future impacts. The twin satellites of the GRACE Follow-On mission, in operation since June 2018, continue and extend the groundbreaking mass change data record from GRACE. In this presentation, I will describe the fascinating technology of contemporary gravity measurements from space, and present break-through science discoveries and every-day applications from the two GRACE missions, such as the variable ice mass loss over Greenland and Antarctica, and the emerging long-term trends of land water storage that impact water availability.

Felix Landerer is the Project Scientist for the joint NASA-GFZ GRACE Follow-On satellite mission at NASA’s Jet Propulsion Laboratory. He earned a degree in Geophysics from the University of Kiel, a doctorate in Physical Oceanography from the Max Planck Institute for Meteorology in Hamburg (Germany), and was a NASA Postdoctoral Fellow at JPL from 2008 to 2010. He explores and studies Earth’s constantly changing hydrosphere by using data from geodetic satellite observations (e.g., from GRACE(-FO) and ocean altimeters), and geodetic ground observations (e.g., GPS, tide gauges) to understand global and regional sea level variations and underlying processes, and to provide relevant data to track water redistribution and availability (e.g., ice mass, aquifer storage) in a changing climate. 

Seminar was recorded on February 25, 2021

 

 

Observing our Magnetic World: When Theory Follows Space Measurements with Mioara Mandea (CNES, France)

Over the last decades, the convergence of novel approaches has led to substantial progress in our understanding of the Earth’s magnetic field characteristics and properties. These advancements have been possible due to the high quality geomagnetic data, which have been obtained either from ground magnetic observatories or from dedicated satellite missions. A radical move took place in 1980, after the launch of the very first satellite carrying a vector magnetometer to measure the full magnetic field, MAGSAT. The state-of-the-art has dramatically changed with measurements obtained from the Oersted, CHAMP, SAC-C satellites, and mostly with the recent ESA Swarm mission, launched in 2013. An overview of these space missions and of our present understanding of the geomagnetic field is given, covering commonly accepted and some of the more controversial aspects. The geomagnetic observations have been crucial in developing new insights and new theories, and a few aspects of the Earth’s deep and shallow processes grasped by the magnetic field are presented, in closest relation with some other geophysical data.

Mioara Mandea is currently the Programme Manager for Solid Earth at the Directorate for Innovation, Applications and Science at Centre National d’Etudes Spatiales in Paris (French Space Agency). Over recent decades, she has been involved in many activities of the International Association of Geomagnetism and Aeronomy (both Secretary General and President), European Geosciences Union (General Secretary and Chair of Outreach Committee), American Geophysical Union (Chair of Education Award Committee), International Space Science Institute (Chair of Science Committee), Commission for the Geological Map of the World (President of the Sub-commission of Geophysical maps), to name the most important. Mioara Mandea has published more than 250 papers, has been involved in organising many workshops and conferences, and has also led several multi-partner research projects or work packages within projects at different national and EU levels. Mioara Mandea is member of the Academy of Romanian Scientists, Academia Europea, Académie Royale de Belgique, Russian Academy of Science. She received the International Award of AGU, the Petrus Peregrinus medal of EGU, and the prestigious French “Ordre National de Mérite” (more information on www.mioara-mandea.eu).

Seminar was recorded on February 18, 2021 

SMOS, Soil Moisture and Sea Surface Salinity with Yann Kerr (CESBIO, France)

SMOS, a L Band radiometer using aperture synthesis to achieve a good spatial resolution, was successfully launched on November 2, 2009. It was the first instrument to operate operationally at L band – the first instrument thus to deliver direct estimates of surface soil moisture and sea surface salinity – and the first interferometer flown in space. A true game changer! SMOS carries a single payload, an L band 2D interferometric, radiometer in the 1400-1427 MHz protected band. This wavelength penetrates well through the vegetation and the atmosphere is almost transparent enabling to infer both soil moisture and vegetation water content, the so called L-VOD. SMOS achieves an unprecedented spatial resolution of 50 km at L-band maximum (43 km on average) with multi angular-dual polarized (or fully polarized) brightness temperatures over the globe and with a revisit time smaller than 3 days. SMOS has been now acquiring data for almost 12 years. The data quality exceeds what was expected, showing exceptional sensitivity and stability. The data is however impaired by man-made emission in the protected band, leading to degraded measurements in several areas including parts of Europe and China. Many different international teams are now addressing data use in various fields. We have now acquired data over a number of significant “extreme events” such as droughts and floods giving useful information of potential applications and are now working on the coupling with other models and or disaggregation to address soil moisture distribution over watersheds. Furthermore, we are also concentrating efforts on water budget and regional impacts. From all those studies, it is now possible to express the “lessons learned” and derive a possible way forward. This seminar thus gives an opportunity to present the achievements of the SMOS mission, a description of its main elements, and a taste of the results including performances at brightness temperature as well as at geophysical parameters level and how they are being put in good use in many domains.

Yann Kerr’s fields of interest include the theory and techniques for microwave and thermal infra-red remote sensing of the Earth, with emphasis on hydrology, water resources management and vegetation monitoring. He is involved in many space missions from conception to launch, and post-launch validation as well as to derivation of applications including EOS principal investigator of interdisciplinary investigations from 1990-1999 and PI of the precursor of the use of Scatterometer (SCAT – on board of the European Remote Sensing (ERS) satellite) data over land, Co-investigator on Interface Region Imaging Spectrograph (IRIS), Optical Spectrograph and Infra-red Imager System (OSIRIS), and Hydrosphere State (Hydros) Satellite Mission for NASA. Yann Kerr was science advisor for Multifrequency Imaging Microwave Radiometer (MIMR) and Land Surface Temperature Mission (LSTM) and Co-I on Advanced Microwave Scanning Radiometer (AMSR). In 1990, he developed interferometric concepts applied to passive microwave Earth observation and was subsequently the science lead on the Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) project for European Space Agency (ESA) with Matra Marconi Space (MMS) and Observatoire Midi-Pyrénées (OMP). In 1997, he first proposed the development of the SMOS Mission that was eventually selected by CNES and ESA in 1999 and launched in 2009 with the incumbent as the SMOS mission Lead-Investigator and Chair of the Science Advisory Group. Yann Kerr also leads SMOS science activities coordination in France and organised all the first SMOS Science workshops and is a member of the Soil Moisture Active Passive (SMAP) Science team. Yann Kerr was deputy director of LERTS and CESBIO and Director of CESBIO. 

 

Seminar was recorded on February 11, 2021

CryoSat – A Decade of Polar Altimetry with Andrew Shepherd (University of Leeds, UK)

CryoSat-2 is ESA’s first satellite mission dedicated to measuring changes in the cryosphere and its measurements have transformed our capacity to study the polar regions. Thanks to CryoSat-2, we now have an altogether new appreciation of how Earth’s ice sheets, ice shelves, sea ice, glaciers, and polar oceans are evolving. As global temperatures have risen, so to have rates of snowfall, ice melting, and sea level rise, and each of these changes impacts upon the neighbouring land, marine, and atmospheric environments. CryoSat-2 measurements are now central to our awareness and understanding of Arctic and Antarctic environmental change; a case in point is the marine ice sheet instability that is underway in West Antarctica, widely understood to be among the greatest contemporary imbalances in the climate system, whose evolution has been charted in satellite altimeter data since its onset. In this presentation, Andrew Shepherd will introduce the CryoSat-2 mission concept, describe the technical advances that have improved our capability to monitor land ice, sea ice, and the polar oceans, and review a series of flagship studies that have allowed both long-standing and unanticipated scientific problems in cryospheric research to be solved.

Andy Shepherd is Professor of Earth Observation at the University of Leeds, Director of the NERC Centre for Polar Observation and Modelling, Principal Scientific Advisor to the European Space Agency CryoSat satellite mission, and co-leader of the ESA-NASA Ice Sheet Mass Balance Inter-comparison Exercise. He uses satellites to study the physical processes of Earth’s climate, and his main contributions to science have involved developing remote observations of the cryosphere, with particular emphasis on radar interferometry and radar altimetry. He has also led field campaigns in Europe, Africa, Greenland and Antarctica, to calibrate and validate satellite missions. Andrew was educated in the Department of Physics and Astronomy at the University of Leicester, and prior to working at Leeds he has held academic posts at University College London, at the University of Cambridge, and at the University of Edinburgh. He has co-authored over journal 100 papers that are often reported in the media, and he regularly contributes to broadcast documentaries such as the BBC’s Blue Planet 2 and Climate Change: the Facts. Andrew was awarded a Philip Leverhulme Prize in 2008 and a Royal Society Wolfson Research Merit Award in 2014.

 

Seminar was recorded on February 4, 2021. 

From Satellite Observations and Atmospheric Modeling to Air Quality Forecasts with Guy Brasseur (Max Planck Institute for Meteorology, Hamburg, Germany)

According to the World Health Organization, poor outdoor air quality is responsible for the premature death of about 4 million people each year. From a health point off view, air pollution is currently the worse environmental problem facing humanity, particularly in low- and medium income countries. In the last decades, remote sensing observations from space have provided unique information on the abundance, annual variations and long-term trends of chemical species including ozone in the stratosphere. Today, a grand and difficult challenge is to probe the troposphere at high spatial and temporal resolution to monitor air quality at the regional and even local scales. The TROPOMI instrument on Sentinel 5p, for example, provides unique information on nitric oxide, a major pollutant emitted by traffic, industrial operations, energy generation, etc. while several forthcoming geostationary satellites including the Korean GEMS mission, just launched, will measure chemical species at a  spatial resolution than higher than most model resolutions.

Space observations and in situ monitoring of chemical species in the atmosphere together with information about surface emissions and atmospheric chemical and physical processes provide the basis for the development of air quality forecast systems. An important concern from policymakers is the attribution of the sources responsible for our pollution episodes. The seminar will present an integrated view on these questions.

Guy Brasseur is a Senior Scientist and former Director at the Max Planck Institute for Meteorology in Hamburg, Germany. He is also a Distinguished Scholar and a former Associate Director at the National Center for Atmospheric Research (NCAR) in Boulder, CO, USA. He is a Visiting Professor at the Polytechnic University of Hong Kong. Brasseur was the Chair of the International Geosphere Biosphere Program and more recently of the World Climate Research Program. His interests include atmospheric chemistry and climate change. His early focus was first on stratospheric ozone and chemistry of the upper atmosphere. He has contributed to the development of global atmospheric chemistry models and climate models.

Seminar was recorded on January 21, 2021