Overview of Akatsuki data products: definition of data levels, method and accuracy of geometric correction

Kazunori Ogohara, Masahiro Takagi, Shin ya Murakami, Takeshi Horinouchi, Manabu Yamada, Toru Kouyama, George L. Hashimoto, Takeshi Imamura, Yukio Yamamoto, Hiroki Kashimura, Naru Hirata, Naoki Sato, Atsushi Yamazaki, Takehiko Satoh, Naomoto Iwagami, Makoto Taguchi, Shigeto Watanabe, Takao M. Sato, Shoko Ohtsuki, Tetsuya FukuharaMasahiko Futaguchi, Takeshi Sakanoi, Shingo Kameda, Ko ichiro Sugiyama, Hiroki Ando, Yeon Joo Lee, Masato Nakamura, Makoto Suzuki, Chikako Hirose, Nobuaki Ishii, Takumi Abe

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We provide an overview of data products from observations by the Japanese Venus Climate Orbiter, Akatsuki, and describe the definition and content of each data-processing level. Levels 1 and 2 consist of non-calibrated and calibrated radiance (or brightness temperature), respectively, as well as geometry information (e.g., illumination angles). Level 3 data are global-grid data in the regular longitude–latitude coordinate system, produced from the contents of Level 2. Non-negligible errors in navigational data and instrumental alignment can result in serious errors in the geometry calculations. Such errors cause mismapping of the data and lead to inconsistencies between radiances and illumination angles, along with errors in cloud-motion vectors. Thus, we carefully correct the boresight pointing of each camera by fitting an ellipse to the observed Venusian limb to provide improved longitude–latitude maps for Level 3 products, if possible. The accuracy of the pointing correction is also estimated statistically by simulating observed limb distributions. The results show that our algorithm successfully corrects instrumental pointing and will enable a variety of studies on the Venusian atmosphere using Akatsuki data.

Original languageEnglish
Article number167
JournalEarth, Planets and Space
Volume69
Issue number1
DOIs
Publication statusPublished - Dec 1 2017

Keywords

  • Data product
  • Ellipse-fitting technique
  • Pointing correction
  • Venus

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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    Ogohara, K., Takagi, M., Murakami, S. Y., Horinouchi, T., Yamada, M., Kouyama, T., Hashimoto, G. L., Imamura, T., Yamamoto, Y., Kashimura, H., Hirata, N., Sato, N., Yamazaki, A., Satoh, T., Iwagami, N., Taguchi, M., Watanabe, S., Sato, T. M., Ohtsuki, S., ... Abe, T. (2017). Overview of Akatsuki data products: definition of data levels, method and accuracy of geometric correction. Earth, Planets and Space, 69(1), [167]. https://doi.org/10.1186/s40623-017-0749-5