Researchers from Saitama University, Kyoto University, Miyazaki University, Nihon University, and RIKEN have reported that the atmospheric pressure in the mesosphere/lower thermosphere (altitude 70-115 km) is about 1% per year, based on observation data from X-ray astronomical satellites. It revealed that it is contracting at a pace of 0.5%.

 It is thought that the atmosphere above 20 km will conversely cool and shrink as a result of global warming due to the effects of greenhouse gases.This theory of atmospheric contraction has been predicted for more than half a century. None.

 Under these circumstances, in this research, we focused on the observation data affected by the earth's atmospheric occultation, which is essentially unusable for observing celestial bodies, among the astronomical observation data from X-ray astronomical satellites.Atmospheric density can be measured by examining the attenuation rate of X-ray intensity at the timing when X-rays from celestial bodies are affected by the Earth's atmosphere.

 Using this method, we investigated long-term changes in atmospheric density retroactively from observation data obtained from 5 to 1994 by five U.S. and Japanese X-ray astronomical satellites. It was found that it has been gradually declining over time, and has decreased by about 2022% in 70 years.The decrease in atmospheric density means that the thin upper layer of the atmosphere has contracted and fallen. become.We also confirmed that this pace of density decline is consistent with predictions from state-of-the-art atmospheric simulations that take into account increases in greenhouse gases.

 Since the method developed in this research can be applied to many X-ray astronomical satellites in the future, it will be useful for monitoring the density of the upper atmosphere in the future.The results of this research are expected to contribute to social and economic activities, such as deepening our understanding of global warming and improving the accuracy of estimating the orbits and lifetimes of artificial satellites.

Paper information:[Journal of Geophysical Research: Space Physics] Long-Term Density Trend in the Mesosphere and Lower Thermosphere from Occultations of the Crab Nebula with X-Ray Astronomy Satellites

Kyoto University

Foster a free academic style based on the spirit of "self-respect for self-weight" and open up a world of creative learning.

With the motto of self-study, we will continue to maintain a free academic style that is not bound by common sense, and develop human resources who have both creativity and practical ability.We provide an inclusive learning space that allows for diverse and hierarchical choices so that students themselves can choose a solid future through valuable trial and error. […]

Saitama University

Discover and grow your new self at Saitama University, which develops human resources who will lead the next generation

Saitama University was founded in 1949 (Showa 24) by integrating the former Urawa High School, Saitama Normal School and Saitama Youth Normal School as a new national university.With five faculties of liberal arts, economics, education, science, and engineering, advanced educational content based on solid research capabilities, improvement of research capabilities that contribute to the development of new knowledge horizons and solutions to contemporary issues […]

Nihon University

Learn for yourself, think for yourself, open your way.Developing education and research that takes advantage of economies of scale

Nihon University is the largest comprehensive university in Japan with a history and tradition of more than 130 years.With "self-creation" as our educational philosophy, we aim to be "the most educational university in Japan".Currently, it has 16 faculties and 86 departments, and is thoroughly instructed by a small number of people in seminars, foreign language education, experiments and practical training.[…] As a Japanese

Miyazaki University

Cultivate abundant human and practical skills with a view to the world and contribute to medical care in the community

Under the slogan "Let's start from the region with a view to the world," Miyazaki University inherits and develops intellectual heritage related to science and culture as a crystal of human wisdom, explores deep science, and preserves the global environment. Aiming to create interdisciplinary life sciences, we have posted as an educational philosophy the development of human resources who can meet the diverse demands of a changing society […].

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