HR: 1340h
AN: A33D-0091    [Abstracts]
TI: Validation of ILAS-II Version 1.4 N$_2$O and CH$_4$ Profiles
AU: * Ejiri, M K
EM: ejiri.mitsumu@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Terao, Y
EM: yterao@fas.harvard.edu
AF: Harvard University, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Sugita, T
EM: tsugita@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Nakajima, H
EM: hide@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Shiotani, M
EM: shiotani@rish.kyoto-u.ac.jp
AF: Research Institute for Sustainable Humanosphere, Kyoto University, Gokasyo, Uji, Kyoto, 611-0011 Japan
AU: Kanzawa, H
EM: kanzawa@ihas.nagoya-u.ac.jp
AF: Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602 Japan
AU: Sasano, Y
EM: sasano@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AB: The Improved Limb Atmospheric Spectrometer-II (ILAS-II) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) measured the vertical profiles of nitrous oxide (N$_2$O) and methane (CH$_4$) profiles at high latitudes in both hemisphere from January to October 2003. Repeatability as a measure of precision defined by a ratio of the standard deviation to the mean value was calculated for N$_2$O and CH$_4$ profiles for the periods when the atmospheric conditions were stable. The repeatability of N$_2$O and CH$_4$ was found to be less than 10% below 30 km, except the N$_2$O at the altitudes of 25$\sim$30 km in the Southern Hemisphere (10$\sim$17%). To evaluate the ILAS-II version 1.4 N$_2$O and CH$_4$ measurements, these profiles are compared with those obtained by balloon-borne sensors (MIPAS-B and MkIV). In addition, the ILAS-II N$_2$O and CH$_4$ profiles are compared statistically with other satellite data (Odin/SMR for N$_2$O and UARS/HALOE for CH$_4$). The criterion for comparison with SMR and HALOE were (1) distance between observed points at the tangent altitude of 20 km by ILAS-II and by SMR/HALOE is less than 300 km/600 km, respectively, and (2) difference of observation time is less than 12 hours. Results of the comparison with MIPAS-B, MkIV and SMR showed that the ILAS-II N$_2$O mixing ratios were $\sim$20% and $\sim$30% lower than them for mixing ratios larger than 100 ppbv in the Northern Hemisphere and the Southern Hemisphere, respectively. ILAS-II CH$_4$ in the Northern Hemisphere showed a tendency to near exponentially 0 ppmv above 25 km or for mixing ratios smaller than 1 ppmv. The tendency was not shown in the ILAS-II CH$_4$ on the Southern Hemisphere. We are investigating the cause of this difference that was seen in the Northern Hemisphere. While, below 25 km or for mixing ratios larger than 1 ppmv in the Northern Hemisphere, ILAS-II CH$_4$ profiles showed a good agreement within $\pm$10% with two balloon and HALOE profiles. In the Southern Hemisphere, ILAS-II CH$_4$ profiles agreed within -10$\sim$+20% with HALOE profiles below $\sim$40 km. In this presentation, we will show more details of the validation and discuss the results and problems.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0340 Middle atmosphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting