2007

  1. Balogh, A., R. Grard, S. Solomon, R. Schulz, Y. Langevin, Y. Kasaba, M. Fujimoto, Mission to Mercury, Space Sci. Rev., 132, 2-4, 611-645, 2007.
  2. Enell, C.-F., E. Arnone, T. Adachi, O. Chanrion, P.T. Verronen, A. Seppala, T. Neubert, T. Ulich, E. Turunen, Y. Takahashi, R.-R. Hsu, Parameterisation of the chemical effect of sprites in the middle atmosphere, Ann. Geophys., 26, 13-27, 2007.
  3. Frey, H.U., S.B. Mende, S.A. Cummer, J.Li, T. Adachi, H. Fukunishi, Y. Takahashi, A. B. Chen, R.-R. Hsu, H.-T. Su, Y.-S. Chang, Halos generated by negative cloud-to-ground lightning, Geophys. Res. Lett., 34, doi:10.1029/2007GL030908, 2007.
  4. Fujiwara, H., R. Kataoka, M. Suzuki, S. Maeda, S. Nozawa, K. Hosokawa, H. Fukunishi, N. Sato, M. Lester, Electromagnetic energy deposition rate in the polar upper thermosphere derived from the EISCAT Svalbard radar and CUTLASS Finland radar observations, Ann. Geophys., 25, 2393-2403, 2007.
  5. Ikeda, H., Y. Arai, K. Hara, H. Hayakawa, K. Hirose, Y. Ikegami, H. Ishino, Y. Kasaba, T. Kawasaki, T. Kohriki, E. Martin, H. Miyake, A. Mochizuki, H. Tajima, O. Tajima, T. Takahashi, T. Takashima, S. Terada, H. Tomita, T. Tsuboyama, Y. Unno, H. Ushiroda and G. Varner, Deep sub-micron FD-SOI for front-end application, Nuc. Inst. Meth. Phys. Res. Sec., A, 579, 2, 701-705, 2007.
  6. Kasaba, Y., T. Takashima, H. Misawa, J. Kawaguchi, Jovian Small Orbiter for magnetospheric and auroral studies associated with solar sail, Adv. Geosci. 2006, 45, 2007.
  7. Kuo, C.-L., A. B. Chen, Y. J. Lee, L. Y. Tsai, R. K. Chou, R. R. Hsu, H. T. Su, L. C. Lee, S. A. Cummer, H. U. Frey, S. B. Mende, Y. Takahashi, H. Fukunishi, Modeling elves observed by FORMOSAT-2 satellite, J. Geophys. Res., 112, doi:10.1029/2007JA012407, 2007.
  8. Nakamura, M., T. Imamura, M. Ueno, N. Iwagami, T. Satoh, S. Watanabe, M. Taguchi, Y. Takahashi, M. Suzuki, T. Abe, G. L. Hashimoto, T. Sakanoi, S. Okano, Y. Kasaba, J. Yoshida, M. Yamada, N. Ishii, T. Yamada, K. Uemizu, T. Fukuhara, K. Oyama, Planet-C: Venus Climate Orbiter mission of Japan, Planet. Space Sci., 55, 12, 1831-1842, 2007.
  9. Ohtsuki, S., N. Iwagami, H. Sagawa, M. Ueno, Y. Kasaba, T. Imamura, E. Nishihara, Imaging spectroscopy of the 1.27-micron O2 airglow with ground-based telescopes, Adv. Space Res., 2007.
  10. Uno, K., T. Kameyama, M. Horihata, N. Asano, K. Ebisawa, T. Tamura, Y. Kasaba, I. Shinohara, O. Miyashita, A. Miura, K. Matsuzaki, H. Murakami, F.A. Furuzawa, The Astronomical Data Sonification Project: An overview of the project and its initial data output, Trans. Info. Social Sci., 10, 1-10, 2007.

2006

  1. Adachi, T., H. Fukunishi, Y. Takahashi, Y. Hiraki, R.-R. Hsu, H.-T. Su, A.B. Chen, S.B. Mende, H.U. Frey, L.C. Lee, Electric field transition between the diffuse and streamer regions of sprites estimated from ISUAL/array photometer measurements, Geophys. Res. Lett., 33, 17, doi:10.1029/2006GL026495, 2006.
  2. Cummer, S., H.U. Frey, S.B. Mende, R.-R. Hsu, H.-T. Su, A. B. Chen, H. Fukunishi, Y. Takahashi, Simultaneous radio and satellite optical measurements of high-altitude sprite current and lightning continuing current, J. Geophys. Res., 111, A10, doi:10.1029/2006JA011809, 2006.
  3. Fujiwara, H., Y. Miyoshi, Characteristics of the large-scale traveling atmospheric disturbances during geomagnetically quiet and disturbed periods simulated by a whole atmosphere general circulation model, Geophy. Res. Lett., 33, L20108, doi:10.1029/2006GL027103, 2006.
  4. Hiraki, Y., H. Fukunishi, Theoretical criterion of charge moment change by lightning for initiation of sprites, J. Geophys. Res., 111, A11, doi:10.1029/2006JA011729, 2006.
  5. Liu, N. Y., V. P. Pasko, D. H. Burkhardt, H. F. Frey, S. B. Mende, H.-T. Su, A. B. Chen, R.-R. Hsu, L.-C. Lee, H. Fukunishi, Y. Takahashi, Comparison of results from sprite streamer modeling with spectrophotometric measurements by ISUAL instrument on FORMOSAT-2 satellite, Geophys. Res. Lett., 33(1), L01101, 2006.
  6. Miyoshi, Y., H. Fujiwara, Day-to-day variations of migrating semidiurnal tide in the mesosphere and thermosphere, Environmental Research in the Arctic 2005, Mem. National Inst. Polar Res. Special Issue, 59, Ed: T. Aso and H. Ito, 199-207, 2006.
  7. Miyoshi, Y., H. Fujiwara, Excitation mechanism of intraseasonal oscillation in the equatorial mesosphere and lower thermosphere, J. Geophys. Res., 111, D14108, doi:10.1029/2005JD006993, 2006
  8. Nakayama, T., K. Takahashi, Y. Matsumi, H. Fujiwara, Laboratory study of O(1S) formation process in the photolysis of O3 and its atmospheric implications, J. Atmos. Chem., 53, 107-122, doi:10.1007/s10874-006-0597-3, 2006.
  9. Takahashi, Y. O., H. Fujiwara, H. Fukunishi, Vertical and latitudinal structure of the migrating diurnal tide in the Martian atmosphere: Numerical investigations, J. Geophys. Res., 111, E1, doi:10.1029/2005JE002543, 2006.

2005

  1. Adachi, T., H. Fukunishi, Y. Takahashi, M. Sato, A. Ohkubo, K. Yamamoto, Characteristics of thunderstorm systems producing winter sprites in Japan, J. Geophys. Res., 110(D11), D11203, doi:10.1029/2004JD005012, 2005.
  2. Engebretson, M. J., T. G. Onsager, D. E. Rowland, R. E. Denton, J. L. Posch, C. T. Russell, P. J. Chi, R. L. Arnoldy, B. J. Anderson, H. Fukunishi, On the source of Pc1-2 waves in the plasma mantle, J. Geophys. Res., 110 (A6), A06201, doi:10.1029/2004JA010515., 2005.
  3. Frey, H. U., S. B. Mende, S. A. Cummer, A. B. Chen, R.-R. Hsu, H.-T. Su, Y.-S. Chang, T. Adachi, T., H. Fukunishi, Y. Takahashi, Beta-type stepped leader of elve-producing lightning, Geophys. Res. Lett., 32(13), L13824, doi:10.1029/2005GL023080, 2005.
  4. Fukunishi, H., Y. Hiraki, L. Tong, K. Nanbu, Y. Kasai, A. Ichikawa, Atomic and molecular processes in lightning-induced sprite events, Atomic and Molecular Data and Their Applications, ed. T. Kato and H. Funaba, D. Kato, American Inst. Phys. Conf. Proc., 771, 101-107, Melville, New York, 2005.
  5. Hirano, Y., H. Fukunishi, R. Kataoka, T. Hasunuma, T. Nagatsuma, W. Miyake, A. Matsuoka, Evidence for the resonator of inertial Alfven waves in the cusp topside ionosphere, J. Geophys. Res., 110(A7), A07218, doi:10.1029/2003JA010329, 2005.
  6. Kuo, C.-L, R.-R. Hsu, A.B. Chen, H.-T. Su, L.-C. Lee, S.B. Mende, H.U. Frey, H. Fukunishi, Y. Takahashi, Electric fields and electron energies inferred from the ISUAL recorded sprites, Geophys. Res. Lett., 32 (19), L19103, 2005.
  7. Maeda, S., S. Nozawa, Y. Ogawa, H. Fujiwara, Comparative study of the high-latitude E-region ion and neutral temperatures in the polar cap and the auroral region derived from the EISCAT radar observations, J. Geophys. Res., 110, A08301, doi:10.1029/2004JA010893, 2005.
  8. Mende, S.B., H.U. Frey, R.-R. Hsu, H.-T. Su, A.B. Chen, L.-C. Lee, D.D. Sentman, Y. Takahashi, H. Fukunishi, D region ionization by lightning-induced electromagnetic pulses, J. Geophys. Res., 110 (A11), A11312, 2005.
  9. Ohkubo, A., H. Fukunishi, Y. Takahashi, T. Adachi, VLF/ELF sferic evidence for in-cloud discharge activity producing sprites, Geophys. Res. Lett., 32(4), L04812, doi:10.1029/2004GL021943, 2005.
  10. Okazaki. Y, H. Fukunishi, Y. Tahakashi, M. Taguchi, S. Watanabe, Lyman alpha imaging of solar activity on the interplanetary hydrogen screen for space weather forecasting, J. Geophys. Res., 110(A3), AO03104, doi:10.1029/2004JA010828, 2005.
  11. Sakanoi, K, H. Fukunishi, Y. Kasahara, A possible generation mechanism of temporal and spatial structures of flickering aurora, J. Geophys. Res., 110(A3), A03206, doi:10.1029/2004JA010549., 2005.
  12. Sato, M., H. Fukunishi, New evidence for a link between lightning activity and tropical upper cloud coverage, Geophys. Res. Lett., 32(12), L12807, doi:10.1029/ 2005GL022865., 2005.
  13. Tao, C., R. Kataoka, H. Fukunishi, Y. Takahashi, T. Yokoyama, Magnetic field variations in the Jovian magnetotail induced by solar wind dynamic pressure enhancements, J. Geophys. Res., 110 (A11), A11208, 2005.
  14. Tong, L. Z., Y. Hiraki, K. Nanbu, H. Fukunishi, Release of positive charges producing sprite halos, J. Atmos. Solar. Terr. Phys., 67 (10), 829-838, 2005.
  15. Tong, L. Z., K. Nanbu, H. Fukunishi, Simulation of gigantic jets propagating from the top of thunderclouds to the ionosphere, Earth Planets Space, 57 (7): 613-617, 2005.
  16. Tong, L. Z., K. Nanbu, H. Fukunishi, Randomly stepped model for upward electrical discharge from top of thundercloud, J. Phy. Soc. Japan, 74 (4), 1093-1095, 2005.

2004

  1. Adachi, T., H. Fukunishi, Y. Takahashi, Roles of the EMP and QE in the generation of columniform sprites, Geophys. Res. Lett., 31(4), L04107, doi:10.1029/ 2003GL019081, 2004.
  2. Fujiwara, H., S. Maeda, M. Suzuki, S. Nozawa, H. Fukunishi, Estimates of electromagnetic and tur-bulent energy dissipation rates under the existence of strong wind shears in the polar lower thermosphere from the EISCAT Svalbard Radar observations, J. Geophys. Res., 109, A07306, doi:10.1029/2003JA010046, 2004.
  3. Hiraki, Y., L. Tong, H. Fukunishi, K. Nanbu, Y. Kasai, A. Ichimura, Generation of metastable oxygen atom O(1D) in sprite halos, Generation of metastable oxygen atom O(D-1) in sprite halos, Geophys. Res. Lett., 31(14), L14105, doi:10.1029/2004GL020048, 2004.
  4. Kataoka, R., H. Fukunishi, S. Fujita, T. Tanaka, M, Itomnaga, Transient response of the Earth’s magnetosphere to a localized density pulse in the solar wind: Simulation of traveling convection vortices, J. Geophys. Res., 109(A3), A03204, doi:10.1029/2003 JA010287, 2004.
  5. Miyoshi, Y., H. Fujiwara, Day-to-day variations of migrating semidiurnal tides simulated by a general circulation model, Adv. Polar Upper Atmos. Res., 18, 87-95, 2004.
  6. Morroka. M, T. Mukai, H. Fukunishi, Current-voltage relationship in the auroral particle acceleration region, Ann. Geophys., 22 (10), 3641-3655, 2004.
  7. Price, C., E. Greenberg, Y. Yair, G. Satori, J, Bor, H. Fukunishi, M. Sato, P. Israelevich, M. Moalem, A. Devir, Z. Levin, J. H. Joseph, I. Mayo, B. Zi, A. Sternlieb, Ground- based detection of TLE-producing intense lightning during the MEIDEX mission on board the space shuttle Columbia, Geophys. Res. Lett., 31(20), L20107, doi:10.1029/2004GL020711, 2004.
  8. Sakanoi K, H. Fukunishi, Temporal and spatial structures of flickering aurora, J. Geophys. Res., 109(A1), A01221 , doi:10.1029/2003JA010081, 2004.
  9. Tong, L. Z., K. Nanbu, H. Fukunishi, Numerical analysis of initiation of gigantic jets connecting thunderclouds to the ionosphere, Earth Planets Space, 56 (11): 1059-1065, 2004.
  10. Tong, L. Z., K. Nanbu, Y. Hiraki, H. Fukunishi, Particle modeling of the electrical discharge in the upper atmosphere above thundercloud, J. Phy. Soc. Japan, 73 (9), 2438-2443, 2004.

2003

  1. Chern, J. L., R. R. Hsu, H. T. Su, S. B. Mende, H. Fukunishi, Y. Takahashi, L. C. Lee, Global survey of upper atmospheric transient luminous events on the ROCSAT-2 satellite, J. Atmos. Solar. Terr. Phys, 65 (5), 647-659, 2003.
  2. Kanzawa, H., T. Sugita, H. Nakajima, G. E. Bodeker, H. Oelhaf, M. Stowasser, G. Wetzel, A. Engel, U. Schmidt, I. Levin, G. C. Toon, B. Sen, J. F. Blavier, S. Aoki, T. Nakazawa, K. W. Jucks, D. G. Johnson, W. A. Traub, C. Camy-Peyret, S. Payan, P. Jeseck, I. Murata, H. Fukunishi, M. von Konig, H. Bremer, H. Kullmann, J. H. Park, L. L. Pan, T. Yokota, M. Suzuki, M. Shiotani, Y. Sasano, Validation and data characteristics of nitrous oxide and methane profiles observed by the Improved Limb Atmospheric Spectrometer (ILAS) and processed with the Version 5.20 algorithm, J. Geophys. Res., 108 (D16), 8003, doi:10.1029/2002JD002458, 2003.
  3. Kataoka, R., H. Fukunishi, K. Hosokawa, H. Fujiwara, A. S. Yukimatu, N. Sato, Y.-K. Tung, Transient production of F region irregularities associated with TCV passage, Ann. Geophys., 21, 1531-1541, 2003.
  4. Kataoka, R., H. Fukunishi, L. J. Lanzerotti, Statistical identification of solar wind origins of magnetic impulse events, J. Geophys. Res., 108 (A12), 1436, doi:10.1029/ 2003JA010202, 2003.
  5. Kurihara, J., K.I. Oyama, Y. Takahashi, Development of a spectrometer to measurethe blue components of sprites, J. Atmos. Solar Terr. Physics, 65, 643-646, 2003.
  6. Miyasato, R., H. Fukunishi, Y. Takahashi, M. J. Taylor, Energy estimation of electrons producing sprite halos using array photometer data, J. Atmos. Solar. Terr. Phys., 65 (5), 573-581, 2003.
  7. Miyoshi, Y., H. Fujiwara, Day-to-day variations of migrating diurnal tide simulated by a GCM from the ground surface to the exosphere, Geophys. Res. Lett., 30, 1789, 2003.
  8. Nakagawa, H., H. Fukunishi, Y. Takahashi, S. Watanabe, M. Taguchi, J. L. Bertaux, R. Lallement, E. Quemerais, Solar cycle dependence of interplanetary Lyman alpha emission and solar wind anisotropies derived from NOZOMI/UVS and SOHO/SWAN observations, J. Geophys. Res., 108 (A10), 8035, doi:10.1029/2003JA009882, 2003.
  9. Sato, M., H. Fukunishi, Global sprite occurrence locations and rates derived from triangulation of transient Schumann resonance events, Geophys. Res. Lett., 30 (16), 1859, doi:10.1029/2003GL017291, 2003.
  10. Sato, M., H. Fukunishi, M. Kikuchi, H. Yamagishi, W. A. Lyons, Validation of sprite-inducing cloud-to-ground lightning based on ELF observations at Syowa station in Antarctica, J. Atmos. Solar. Terr. Phys., 65 (5), 607-614, 2003.
  11. Shiokawa, K., M. K. Ejiri, T. Ogawa, Y. Yamada, H. Fukunishi, K. Igarashi, T. Nakamuraz, A localized structure in OH airglow images near the mesopause region, J. Geophys. Res., 108 (D2), 4048, doi:10.1029/2002JD002462, 2003.
  12. Su, H. T., R. R. Hsu, A. B. Chen, Y. C. Wang, W. S. Hsiao, W. C. Lai, L. C. Lee, M. Sato, H. Fukunishi, Gigantic jets between a thundercloud and the ionosphere, Nature, 423 (6943), 974-976, 2003.
  13. Takahashi, Y.O, H. Fujiwara, H. Fukunishi, M. Odaka, Y.Y. Hayashi, S. Watanabe, Topographically induced north-south asymmetry of the meridional circulation in the Martian atmosphere, J. Geophys. Res., 108 (E3), 5018, doi:10.1029/2001JE001638, 2003.
  14. Takahashi, Y., R. Miyasato, T. Adachi, K. Adachi, M. Sera, A. Uchida, H. Fukunishi, Activities of sprites and elves in the winter season, Japan, J. Atmos. Solar. Terr. Phys.M, 65 (5), 551-560, 2003.

2002

  1. Engebretson, M. J., W. K. Peterson, J.L. Posch, M.R. Klatt, B. J. Anderson, C. T. Russell, H. J. Singer, R. L. Arnoldy, H. Fukunishi, Observations of two types of Pc 1-2 pulsations in the outer dayside magnetosphere, J. Geophys. Res., 107 (A12), 1451, doi:10.1029/ 2001JA000198, 2002.
  2. Fukunishi, H., Lightning effects in the ionosphere, Rev. Radio Sci. 1999- 2002, ed. W.R. Stone, 775-799, 2001.
  3. Fukunishi, H., R. Kataoka, L. J. Lanzerotti, Magnetic impulse events and related Pc 1 waves in the cusp and LLBL region observed by a ground magnetometer network, Space Weather Study Using Multipoint Techniques, ed. L.-H. Lyu, 237-241, Pergamon, Amsterdam, 2002.
  4. Fukunishi, H., Y. Watanabe, A. Uchida, Y. Takahashi, Spatial and temporal structures of sprites and elves observed by array photometers, Space Weather Study Using Multipoint Techniques, ed. L.-H. Lyu, 283-288, Pergamon, Amsterdam, 2002.
  5. Kataoka, R., H. Fukunishi, L. J. Lanzerotti, T. J. Rosenberg, A. T. Weatherwax, M. J. Engebretson, J. Watermann, Traveling convection vortices induced by solar wind tangential discontinuities, J. Geophys. Res., 107 (A12), 1455, doi:10.1029/2002JA009459, 2002.
  6. Maeda, S., S. Nozawa, M. Sugino, H. Fujiwara, M. Suzuki, Ion and neutral temperature distributions in the E-region observed by the EISCAT Tromso and Svalbard radars, Ann. Geophys., 20, 1415-1427, 2002.
  7. Miyasato, R., M. J. Taylor, H. Fukunishi, H. C. Stenbaek-Nielsen, Statistical characteristics of sprite halo events using coincident photometric and imaging data, Geophys. Res. Lett., 29 (21), 2033, doi:10.1029/2001GL014480, 2002.
  8. Sakanoi, T., H. Fukunishi, S. Okano, N. Sato, H. Yamagishi, A. S. Yukimatu, Dynamical coupling of neutrals and ions in the high-latitude F region: Simultaneous FPI and HF radar observations at Syowa Station, Antarctica, J. Geophys. Res., 107 (A11), 1388, doi:10.1029/2001JA007530, 2002.
  9. Sugita, T., T. Yokota, H. Nakajima, H. Kanzawa, H. Nakane, H. Gernandt, V. Yushkov, K. Shibasaki, T. Deshler, Y. Kondo, S. Godin, F. Goutail, J.P. Pommereau, C. Camy-Peyret, S. Payan, P. Jeseck, J. B. Renard, H. Bosch, R. Fitzenberger, K. Pfeilsticker, M. von Konig, H. Bremer, H. Kullmann, H. Schlager, J. J. Margitan, B. Stachnik, G. C. Toon, K. Jucks, W. A. Traub, D. G. Johnson, I. Murata, H. Fukunishi, Y. Sasano, Validation of ozone measurements from the Improved Limb Atmospheric Spectrometer, J. Geophys. Res., 107 (D24), 8212, doi:10.1029/2001JD000602, 2002.
  10. Zhao, Y., K. Strong, Y. Kondo, M. Koike, H. Irie, C. P. Rinsland, N. B. Jones, K. Suzuki, H. Nakagima, H. Nakane, I, Murata, Spectroscopic measurements of tropospheric CO, C2H6, C2H2 and HCN in northern Japan including a detection of enhanced emissions from the eastern Siberia fires in 1998, J. Geophys. Res., 107, D18, ACH2-1, doi:10.1029/2001JD000748, 2002.

2001

  1. Hobara Y, N. Iwasaki, T. Hayashida, M. Hayakawa, K. Ohta, H. Fukunishi, Interrelation between ELF transients and ionospheric disturbances in association with sprites and elves, Geophys. Res. Lett., 28(5), 935-938, 2001.
  2. Kataoka, R., H. Fukunishi, L. J. Lanzerotti, C. G. Maclennan, H. U. Frey, S. B. Mende, J. H. Doolittle, T. J. Rosenberg, A. Weatherwax, Magnetic impulse event: a detailed case study of extended ground and space observations, J. Geophys. Res., 106(A11), 25873-25889, 2001.
  3. Kubota, M., H. Fukunishi, S. Okano, Characteristics of medium- and large-scale TIDs over Japan derived from OI 630-nm nightglow observation, Earth Planets Space, 53(7), 741-751, 2001.
  4. Takahashi Y, H. Fukunishi, The dynamics of the proton aurora in auroral breakup events, J. Geophys. Res., 106 (A1), 45-63, 2001.
  5. Yamada, Y, H. Fukunishi, T. Nakamura, T. Tsuda, Breaking of small-scale gravity wave and transition to turbulence observed in OH airglow, Geophys. Res. Lett., 28 (11), 2153-2156, 2001.

火星大気散逸の数値シミュレーション

HEAD_KT

現在の火星は地球に比べて大気が薄く、その気候は寒冷で乾燥し、生命活動には過酷な環境です。しかし、近年の衛星探査によって、かつては地球と同様分厚い大気をもつ、温暖で湿潤な惑星であったと分かってきました。何故火星に存在した大量の大気・水は失われてしまったのでしょうか?そして、結果として生命の存在しない「死の惑星」となってしまったのでしょうか?その主な原因の1つは宇宙空間への大気の流出だといわれいます。私はこの火星からの大気流出を、数値シミュレーションによって調べています。現在は、特に酸素の流出の太陽活動に対する依存性を明らかにしようとしています。

金星硫酸雲の生成・消滅数値モデリング

We are starting to investigate the cloud formation, chemical reactions, and their radiative effect which affects the atmospheric dynamics in the Venusian middle atmosphere, using a VGCM (Venus General Circulation Model). Recently we introduced evaporation/condensation processes of the sulfuric aerosol into the VGCM developed by Ikeda [2011], and reproduced the latitudinal/vertical distribution of the sulfuric aerosol which is consistent with previous observations. In this presentation, we will show you the results and the future steps of our research.
Venusian sulfuric acid cloud deck, which exists in the altitude of 50km-70km, is considered to have a strong influence on the thermal balance of the Venusian atmosphere. The component of the cloud particle is mainly sulfuric aerosol which is formed by the reactions between SO2, O and H2O. The sulfuric acid droplets are divided into 4 groups according to the size; mode1 (0.3µm), mode2 (1.0µm), mode2’ (1.4µm) and mode3 (3.56µm) as defined in Crisp. [1986]. Each mode has its own characteristics of vertical distribution and thermal absorption efficiency, so the reproduction of the vertical/latitudinal distribution of those modes in the numerical model is important to simulate the general circulations in the Venusian atmosphere.
We have investigated the cloud distributions in the Venusian atmosphere using a VGCM based on the CCSR/NIES/FRCGC AGCM [Ikeda, 2011]. The model has 32(latitude) X 64(longitude) grid points and 52 vertical levels from the surface up to 95km. It successfully reproduces the zonal and meridional winda including super-rotation and Hadley circulation in the Venusian atmosphere. The current model calculates the radiative effects of clouds and molecules from fixed distributions defined in Crisp [1986] and Pollack et al. [1993], so we plan to implement into the model the radiative effects which will be consistent with the calculated cloud distributions, as well as the chemical reactions for production of the clouds.
We introduced the evaporation/concentration process of H2SO4 and simulated the evaporation of aerosols in the lower atmosphere which has the higher temperature and the condensation of aerosols in the upper atmosphere. The model calculates the saturated mixing ratio in each grid from the saturated vapor pressure curve derived from Ayers [1980], and compared it to the H2SO4 mixing ratio at the grid. We assumed that if the H2SO4 mixing ratio (sum of vapor and cloud) is larger than the calculated saturated mixing ratio, the supersaturated H2SO4 concentrates as an aerosol, and if not the H2SO4 aerosol all evaporates. The generated H2SO4aerosols are distributed into 4 modes at each altitude according to the abundance ratio based on the observation [Crisp, 1986]. We are implementing the effects of latent heat by the condensation /evaporation using the method of successive approximation.
Because of this improvement, every mode of the cloud now evaporates below 50km altitude. After the calculation of 1 Venusian day (117 terrestrial days), mode 3 aerosol gets the equilibrium state at 50km altitude.
Also the amount of mode2 aerosol largely decreased in low and mid latitudes of 60km-80km altitude, while increased in the atmosphere above 80km in all latitudes and 60km-80km altitude in high latitudes, in comparison with the model without the evaporation/concentration processes [Kuroda et al., 2013]. We consider that the difference is because the sulfuric aerosol is enhanced to evaporate especially in the equatorial middle atmosphere where the temperature is high, and the transport of H2SO4 to higher altitudes and latitudes by Hadley circulation is enhanced due to the phase change.
We will continue to improve our model to increase the accuracy of the simulation of the vertical/latitudinal cloud distribution. In the presentation, we plan to show the numerical results with radiative effects and chemical reactions which is connected to the cloud formation.

地球超高層大気の微量成分分析

Credit by JAXA

Credit by JAXA

「大気微量成分」とは、大気中に含まれる成分のうち窒素・酸素以外、その混合比が1%にも満たない成分のこと。オゾンや二酸化炭素がその代表です。量はわずかでも地球大気の温度や循環などの環境に与える影響が大きく、また窒素酸化物等による大気汚染のように生物に直接影響を与える現象もあります。我々は、その中でオゾンを中心とした各微量成分の変動を、主に分光学的な手法、例えばフーリエ変換型赤外分光計を用いた成層圏・対流圏の観測や、高高度気球を用いた上部成層圏の観測によって研究しています。

“Atmospheric trace species” is the component which mixing ratio is less than 1%, like O3, CO2, CH4 etc. Despite of their small amount, they affect a lot to temperature and circulation of the atmosphere. It also affects human health in the case of air pollution by NOx etc. We have observed the variation of these species mainly by spectroscopic methods such as FTIR and high-altitude balloon observations.

大気散逸の数値シミュレーション

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太陽風や太陽放射の影響によって、惑星の大気が宇宙空間に剥ぎ取られる「大気散逸」現象。大気散逸現象は、惑星大気の散逸を引き起こす物理機構そのものが研究対象として魅力的であるだけでなく、惑星大気の進化や多様性が生じる原因を理解し、ハビタブル惑星(生命が居住可能な惑星)が成立する条件を理解する上でも重要です。私達は、非磁化惑星の電離圏と太陽風の相互作用を包括的に解く電磁ハイブリッド(粒子イオンと流体電子の混成)シミュレーションや磁気流体力学(MHD)シミュレーションのコードを世界に先駆けて開発し、惑星起源の電離大気がどのような物理機構により、どのような経路で宇宙空間に散逸するのかを理論的なアプローチで明らかにしてきました。また、理論・シミュレーションに加えて、東北大学が参画する衛星ミッションや地上望遠鏡プロジェクトとの連携を進め、火星、金星、系外惑星などにおける電離・中性大気散逸機構と大気進化の解明、およびハビタブル惑星の成立条件の理解を目指しています。

 

成層圏突然昇温の解明

Credit by NASA

Credit by NASA

The final target of this research is to find out the potential response of the atmospheric compositions affected by Sudden Stratospheric Warming (SSW) in the upper stratosphere and mesosphere. A SSW is a dramatic middle atmosphere event where the polar vortex of westerly (eastward) winds in the winter hemisphere abruptly (i.e. over the course of a few days) slows down (Minor warming) or even reverses direction (Major warming). During such events, the polar stratosphere exhibits warming of tens of degrees over a few days and polar mesospheric cooling has also been observed during SSWs. Over the past decades, satellite instruments have observed the impact of SSW events on minor constituents like carbon monoxide (CO), ozone (O3), nitrous oxide (N2O) and water vapor (HO2). It is now clear that SSWs are dynamical disturbances affecting the entire middle and upper atmosphere, in addition to perturbing the tropospheric circulation (Kvissel, O.-K., et al., 2011). We investigated the impact of SSW in the stratosphere and lower mesosphere using newly obtained data with SMILES (Superconducting subMillimeter Limb Emission Sounder).