OBSERVATION OF STRATOSPHERIC NO_2 AT SYOWA STATION, ANTARCTICA

元データ 国立極地研究所

概要

Ground based observations of NO_2 and O_3 using visible spectrometers have been made at Syowa Station (69°S) since March 1990. The NO_2 slant column amounts observed at the solar zenith angle of 90°(sunrise and sunset) exhibit a large seasonal variation, decreasing with shortening daylight hours in fall, reaching a minimum of about 1×(10)^<16>(cm)^<-2> in midwinter and increasing to a maximum of about 16×(10)^<16>(cm)^<-2> in midsummer. The recovery of NO_2 in spring is 2-3 times slower than the fall decay, because the heterogeneous chemistry on PSCs, the conversion of NO_x into HNO_3,is effective from midwinter to early spring, and NO_y is removed from the stratosphere through gravitational sedimentation of PSCs particles. In late spring the PSCs decrease and NO_2 increases because of the transport of air from lower latitudes. Following the eruption of Mt. Pinatubo (15°N) in June 1991,the NO_2 amounts in midsummer of 1991 were lower by 20-30% than those in 1990. The NO_2 amount in midsummer increased year after year and recovered to the 1990 level by 1994. The NO_2 amount in fall also recovered since 1992; however, the rate of recovery is smaller than in summer. The NO_2 level in fall of 1993 was as low as those in 1992. On the other hand, the rate of recovery in the box model using the observed aerosol surface areas by SAGE (S. SOLOMON et al., J. Geophys. Res., 99,3509,1994) is larger than that observed at McMurdo and Syowa Stations. This may suggest that another factor delays the NO_2 recovery in fall. NO_2 levels in winter have a positive correlation with temperature at 20 and 70 hPa (about 25 and 18km, respectively). In colder winters such as 1990 and 1993,the NO_2 levels were lower than those in other years. This may be due to the difference in the location of the polar vortex boundary relative to Syowa Station. The NO_2 amount and the temperature are considered to be lower deep inside the vortex as compared to near the boundary. In spring, the NO_2 and O_3 amounts and the temperature largely change when the vortex boundary crosses over Syowa Station. The vortex boundary can be clearly seen in the total O_3 maps obtained by TOMS. The monthly mean O_3 values suggest that Syowa Station was located deep inside of the vortex in October 1992 when the NO_2 level was lower than in other years. In contrast, Syowa Station was located near the edge of the vortex in October 1991 when the NO_2 level was much higher.

著者

張 紀久夫 阪大基:福井工大工
Yamanouchi Takashi National Institute of Polar Research
AOKI Shuhji National Institute of Polar Research
Kondo Yutaka Solar-Terrestrial Environment Laboratory, Nagoya University
Koike Makoto Solar-Terrestrial Environment Laboratory, Nagoya University
Koike Makoto Solar Terrestrial Environment Laboratory Nagoya University
Yamanouchi Takashi National Institute For Polar Research
KAWAGUCHI Akane Solar Terrestrial Environment Laboratory, Nagoya University
NAKAJIMA Hideaki Solar Terrestrial Environment Laboratory, Nagoya University
AOKI Shuhji Faculty of Science, Tohoku University
KOIDE Michihiro Faculty of Science, Tohoku University
NAGAO Ippei Institute for Hydrospheric-Atmospheric Sciences, Nagoya University
IWAI Kunimoto Faculty of Education, Shinsyu University
Koide Michihiro Faculty Of Science Tohoku University
Aoki S Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
清水 明 東大教養
Aoki Shuji Center For Atmospheric And Oceanic Studies Graduate School Of Sci. Tohoku Univ.
Nagao Ippei Institute For Hydrospheric And Atmospheric Sciences Nagoya University
Aoki Shuhji Faculty Of Science Tohoku University
Aoki Syuji National Institute Of Polar Research
Kondo Yutaka Unmanned Aircraft Planning Group:solar Terrestrial Environmental Laboratory Nagoya University:nissan
Iwai Kunimoto Faculty Of Education Shinsyu University
Iwai Kunimoto Faculty Of Education Shinshu University
Kondo Y Nagoya Univ. Nagoya
Kawaguchi Akane Solar Terrestrial Environment Laboratory Nagoya University
Nakajima Hideaki Solar Terrestrial Environment Laboratory Nagoya University
清水 明 Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
Yamada T Geosystems Inc.
Yamanouchi Takashi National Inst. Of Polar Res. And Dep. Of Polar Sci. The Graduate Univ. For Advanced Studies 10-3 Mid
Yamanouchi Takashi National Institute Of Polar Research 10-3 Midoricho Tachikawa Tokyo Japan.
Yamada Tomomi Geosystems Inc.

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