Physics Dept Seminar

March 3, Tuesday (*SPECIAL DAY*)

Earth Radiative Budget as Measured by Uvsq-Sat Constellation since 2021

& Research Opportunities in France

Drs. Mustapha Meftah & Alain Sarkissian

Laboratoire Atmosphères Et Observations Spatiales (LATMOS), France

(Solar-Terrestrial Physics & Physics Career, Host: Hyomin Kim)

Time: 11:45 am - 12:45 pm with 11:30 am teatime

Room: ECE 202

PART I: The Earth’s Radiation Budget (ERB) is a critical component for understanding the planet’s climate system, as it governs the balance between incoming solar energy and outgoing thermal radiation. Accurate monitoring of the ERB, combined with Ocean Heat Content (OHC) measurements, is essential to assess Earth’s Energy Imbalance (EEI) and its implications for global warming. This paper presents new results on the ERB based on data from the Uvsq-Sat and Inspire-Sat nanosatellite missions, which operated from 2021 to 2024. These satellites constitute the first European constellation demonstrator designed for broadband, Wide Field-Of-View (WFOV) measurements of the ERB. While WFOV instruments provide enhanced temporal and spatial coverage, they do not replace the need for Narrow Field-Of-View (NFOV) measurements, such as those provided by the established Clouds and the Earth’s Radiant Energy System (CERES) instruments. Instead, they are designed to complement them. By using data from both the WFOV constellation and CERES instruments to measure Reflected Solar Radiation (RSR) and Outgoing Longwave Radiation (OLR), we estimate the EEI and monitor its evolution. Our analysis reveals a generally good agreement between Uvsq-Sat and CERES data for EEI from 2021 through the end of 2024. Over this period, EEI derived from Uvsq-Sat averaged +0.87 ± 0.23 Wm^−2, closely matching the recent CERES trend. Both datasets indicate a peak in EEI in mid-2023, followed by a decline throughout 2024, likely reflecting stabilizing feedbacks triggered by the 2023 El Niño event. Importantly, this short-term decline occurred within a sustained upward trend in EEI since 2013, as shown by CERES observations, with solar activity having a negligible impact. Comparisons with OHC measurements confirm ongoing ocean heat accumulation, consistent with the rising decadal trend in EEI. These insights underscore the importance of continuous, high-frequency observations to capture the complex and rapidly evolving processes influencing Earth’s energy balance. Demonstrations using nanosatellites at different local times illustrate the advantages of small satellite constellations for improved monitoring frequency and coverage, particularly for variables that change over short time scales, such as RSR, also known as Outgoing Shortwave Radiation (OSR).

PART II: The Académie Spatiale d’Île-de-France aims to unite, improve, and promote training activities in the Paris region’s space sector. It works to raise young people’s awareness of the diversity of careers in the space sector and to build a community around major strategic themes: the environment, space exploration, privatization and competition in the sector, the emergence of NewSpace and agile methods, the development of payloads, and propulsion challenges. Among its actions, particular attention is devoted to inter-university cooperation, women’s representation, equal opportunities, and international outreach. We are inviting international students to come to our labelled institutions in Paris for durations from one month to one year to participate to our activities related to space. The second part of this presentation will introduice our University, the University of Versailles-Saint Quentin en Yvelines or UVSQ, and our space laboratory : the LATMOS, Laboratoire Atmosphères et Observations Spatiales. We will present the many possibilities to build space experiments, our allready existing collaboration within INSPIRE international program (International Satellite Program in Research and Education, https://lasp.colorado.edu/inspire/)