講演・口頭発表等

国際会議
2007年12月12日

Tropospheric ozone-enhanced layers observed over the equatorial Pacific Ocean and the contribution of transport of midlatitude UT/LS air

American Geophysical Union 2007 Fall Meeting
  • Kazuyuki Kita
  • ,
  • Hitomi Hayashi
  • ,
  • S. Taguchi

記述言語
英語
会議種別
ポスター発表
主催者
American Geophysical Union
開催地
San Francisco, CA, USA

Occurence and its seasonal variation of ozone-enhanced layers in the troposphere over euatorial Pacific Ocean were investogated based on ozonesonde data obtained at three Southern Hemisphere ADditional OZonesondes (SHADOZ) sites, Watukosek, American Samoa and San Cristobal, for 6 years between 1998 and 2003. The O3-enhanced layers were frequently observed at the three sites, and their occurrence was about 50% on average. The formation processes of O3-enhanced layers were investigated by meteorological analyses including backward trajectories. Several O3-enhanced layers resulted from the transport of air masses affected by biomass burning. The contribution of this process was about 30% at San Cristobal during February to March period and August to September period, while it was relatively low, about 10%, at Watukosek and Samoa. A significant part of the O3-enhanced layers were attributed to the transport of midlatitude upper-troposphere and lower-stratosphere (UT/LS) air. Meteorological analyses indicated that these layers were originated from equatorward and downward transport of the midlatitude UT/LS air masses through a narrow region between high and low pressure systems around s