HR: 1340h
AN: A13D-0983    [Abstracts]
TI: Analysis of Antarctic Denitrification in 2003 Winter Observed by ILAS-II Onboard the ADEOS-II Satellite
AU: * Nakajima, H
EM: hide@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Saeki, K
EM: saeki.kosuke@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Sugita, T
EM: tsugita@nies.go.jp
AF: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AB: Polar Stratospheric Clouds (PSC) play an important role in ozone destruction in both Arctic and Antarctic stratosphere in winter. They take up gas-phase nitric acid (HNO₃) and grow up when temperature is below nitric acid saturation temperature (T_NAT). When PSC becomes large, it starts to descend and nitric acid is removed from the air mass, resulting in denitrification. The Improved Limb Atmospheric Spectrometer-II (ILAS-II) onboard the Advanced Earth Observing Satellite-II (ADEOS-II) successfully made measurements for the whole Antarctic winter in 2003. ILAS-II measured vertical profiles of O₃, HNO₃, NO₂, H₂O, N₂O, CH₄, ClONO₂, N₂O₅, etc. in addition to the aerosol extinction coefficients at 780 nm. In this study, we analyzed denitrification from ILAS-II HNO₃ and N₂O data in regard to temperature history on the trajectory. The quantity of denitrification was estimated from the difference between measured HNO₃ and HNO₃* assumed from HNO₃-- N₂O correlation. In this analysis, it was found that denitrification was observed only for those airmass that experienced temperature below T_ICE (ice saturation temperature) in late June, 2003. In late July, it was found that most airmass inside the polar vortex was denitrified regardless of temperature history. This suggests that permanent denitrification has occurred in June-July period. The transition of relationship between denitrification and airmass temperature history was discovered from the ILAS-II data. Also, major types of PSC have found to be changed from nitric acid trihydrate (NAT) in June to ice in July, from the ILAS-II data. This is considered to be due to the lack of nitric acid in the airmass due to the denitrification in July.
UR: http://www-ilas2.nies.go.jp
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0322 Constituent sources and sinks
DE: 0340 Middle atmosphere: composition and chemistry
DE: 0341 Middle atmosphere: constituent transport and chemistry (3334)
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005