HR: 1330h
AN: A42C-0777    [PDF]
TI: Measurements of ClONO$_2$ by Improved Limb Atmospheric Spectrometer (ILAS) in the high latitude stratosphere
AU: * Nakajima, H
EM: hide@nies.go.jp
AF: National Institute for Environmental Studies, Japan, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Irie, H
EM: irie.hitoshi@nies.go.jp
AF: National Institute for Environmental Studies, Japan, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Sugita, T
EM: tsugita@nies.go.jp
AF: National Institute for Environmental Studies, Japan, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Yokota, T
EM: yoko@nies.go.jp
AF: National Institute for Environmental Studies, Japan, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AU: Sasano, Y
EM: sasano@nies.go.jp
AF: National Institute for Environmental Studies, Japan, 16-2 Onogawa, Tsukuba, 305-8506 Japan
AB: Improved Limb Atmospheric Spectrometer (ILAS) was a solar-occultation sensor onboard the ADEOS satellite. ILAS measured vertical profiles of O$_3$, HNO$_3$, NO$_2$, N$_2$O, CH$_4$, H$_2$O, and aerosol extinction coefficients at high latitude stratosphere from November 1996 to June 1997 [JGR, ILAS Special Section, Vol. 107, No. D24, 2002]. The latest retrieval algorithm of ILAS (Version 6.0) enabled us to retrieve vertical profiles of ClONO$_2$ and N$_2$O$_5$ with typical vertical resolution of 1.6-2.0 km in addition to these species. The advantage of ILAS ClONO$_2$ measurements is that it continuously measured this gas species at high latitude stratosphere with high vertical resolution. ILAS ClONO$_2$ profiles were compared with correlative balloon-borne measurements by MIPAS-B2 [Fischer and Oelhaf, 1996], FIRS-2 [Johnson et al., 1995], and MkIV [Toon, 1991]. In all comparisons, it was found that ILAS ClONO$_2$ values were systematically lower by around 30% between 15 and 32 km altitudes. Also, the precision and accuracy of ILAS ClONO$_2$ for altitude of 15-35 km were estimated to be around 20-40% and 30%, respectively. The Arctic winter/spring in 1996/1997 was characterized its relatively low temperature and its long lasting polar vortex. Many PSC activities were observed by ILAS in January-March 1997 [Hayashida et al., 2000]. ILAS succeeded to measure vertical profiles of ClONO$_2$ for whole period of this Arctic winter/spring. After the PSC activity in February, enhancement of ClONO$_2$ reaching 1.5 ppbv at around 20 km was observed for the data inside the polar vortex in March. In April 1997, enhanced ClONO$_2$ amount decreased towards 1.0 ppbv at more than 10 days prior to the polar vortex breakup. This suggest the change of partitioning of chlorine species from ClONO$_2$ into HCl at this period. Initial measurements of ClONO$_2$ resumed by ILAS-II onboard the ADEOS-II satellite from April 2003 will also be presented at the meeting.
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: 0933 Remote sensing
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting