Venus atmosphere mapped over a decade using Himawari satellite data
Originally launched to monitor Earth's atmosphere, Himawari-8 and -9 carry Advanced Himawari Imagers (AHIs) capable of capturing Venus near the Earth's rim. The University of Tokyo team, headed by visiting researcher Gaku Nishiyama, leveraged this capability to extract and examine Venus data from the AHI infrared imagery.
Tracking Venusian atmospheric dynamics is challenging due to the limitations of past planetary missions and ground-based observations. "The atmosphere of Venus has been known to exhibit year-scale variations in reflectance and wind speed; however, no planetary mission has succeeded in continuous observation for longer than 10 years due to their mission lifetimes," explained Nishiyama. "Ground-based observations can also contribute to long-term monitoring, but their observations generally have limitations due to the Earth's atmosphere and sunlight during the daytime."
Because Himawari satellites are planned to remain operational through at least 2029, they offer a rare opportunity for extended, high-frequency, and low-noise infrared data collection. The team examined 437 separate Venus sightings within the AHI archive, analyzing brightness temperature changes across multiple infrared bands. This allowed the researchers to evaluate daily and annual atmospheric patterns, including fluctuations in thermal tides and planetary-scale waves.
Their analysis confirmed temporal changes in wave amplitudes, with planetary-scale wave strength appearing to diminish with altitude. Though AHI's temporal resolution limits full interpretation, the results suggest that long-term variations may be linked to broader structural shifts in Venus' atmosphere.
The data also proved useful in identifying calibration mismatches with earlier planetary missions, highlighting another advantage of using meteorological satellites for planetary science.
Looking beyond Venus, Nishiyama emphasized the broader potential of this approach. "I think that our novel approach in this study successfully opened a new avenue for long-term and multiband monitoring of solar system bodies. This includes the moon and Mercury, which I also study at present. Their infrared spectra contain various information on physical and compositional properties of their surface, which are hints at how these rocky bodies have evolved until the present."
Research Report:Temporal variation in the cloud-top temperature of Venus revealed by meteorological satellites
