Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8137059 | Icarus | 2015 | 8 Pages |
Abstract
We present phase curves for Venus in the 1-2 μm wavelength region, acquired with IR1 and IR2 on board Akatsuki (February-March 2011). A substantial discrepancy with the previously-published curves was found in the small phase angle range (0-30°). Through analysis by radiative-transfer computation, it was found that the visibility of larger (â¼1 μm or larger) cloud particles was significantly higher than in the standard cloud model. Although the cause is unknown, this may be related to the recently reported increase in the abundance of SO2 in the upper atmosphere. It was also found that the cloud top is located at â¼75 km and that 1-μm particles exist above the cloud, both of these results being consistent with recent studies based on the Venus Express observations in 2006-2008. Further monitoring, including photometry for phase curves, polarimetry for aerosol properties, spectroscopy for SO2 abundance, and cloud opacity measurements in the near-infrared windows, is required in order to understand the mechanism of this large-scale change.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Space and Planetary Science
Authors
Takehiko Satoh, Shoko Ohtsuki, Naomoto Iwagami, Munetaka Ueno, Kazunori Uemizu, Makoto Suzuki, George L. Hashimoto, Takeshi Sakanoi, Yasumasa Kasaba, Ryosuke Nakamura, Takeshi Imamura, Masato Nakamura, Tetsuya Fukuhara, Atsushi Yamazaki, Manabu Yamada,