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Cause of a lower-tropospheric high-ozone layer in spring over Hanoi
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  • Shin-Ya Ogino,
  • Kazuyuki Miyazaki,
  • Masatomo Fujiwara,
  • Masato I. Nodzu,
  • Masato Shiotani,
  • Fumio Hasebe,
  • Jun Matsumoto,
  • Jacquelyn Cecile Witte,
  • Anne M. Thompson,
  • Hoang Anh Nguyen-Thi,
  • Thu Vinh Nguyen
Shin-Ya Ogino
Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology

Corresponding Author:[email protected]

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Kazuyuki Miyazaki
Jet Propulsion Laboratory, Jet Propulsion Laboratory, Jet Propulsion Laboratory, Jet Propulsion Laboratory
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Masatomo Fujiwara
Hokkaido University, Hokkaido University, Hokkaido University, Hokkaido University
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Masato I. Nodzu
Tokyo Metropolitan University, Tokyo Metropolitan University, Tokyo Metropolitan University, Tokyo Metropolitan University
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Masato Shiotani
Kyoto University, Kyoto University, Kyoto University, Kyoto University
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Fumio Hasebe
Hokkaido University, Hokkaido University, Hokkaido University, Hokkaido University
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Jun Matsumoto
Tokyo Metropolitan University, Tokyo Metropolitan University, Tokyo Metropolitan University, Tokyo Metropolitan University
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Jacquelyn Cecile Witte
National Center for Atmospheric Research, National Center for Atmospheric Research, National Center for Atmospheric Research, National Center for Atmospheric Research
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Anne M. Thompson
NASA-GODDARD, NASA-GODDARD, NASA-GODDARD, NASA-GODDARD
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Hoang Anh Nguyen-Thi
Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration, Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration, Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration, Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration
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Thu Vinh Nguyen
Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration, Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration, Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration, Aero-Meteorological Observatory, Viet Nam Meteorological and Hydrological Administration
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Abstract

The ozonesonde observations in Hanoi, Vietnam, over fourteen years since 2004 have confirmed the enhancement in lower tropospheric ozone concentration at about 3 km altitude in the spring season. We investigated the evolution of the ozone enhancement from analysis of meteorological data, backward trajectories, and model sensitivity experiments. In spring, air masses over Hanoi exhibit strong height dependence. At 3km, the high-ozone air masses originate from the land area to the west of Hanoi, while low-ozone air masses below about 1.5 km are from the oceanic area to the east. Above 4 km, the air masses are mostly traced back to the farther west area. The chemical transport model simulations revealed that precursor emissions from biomass burning in the inland Indochina Peninsula have the largest contribution to the lower tropospheric ozone enhancement, which is transported upward and eastward and overhangs the clean air intrusion from the ocean to the east of Hanoi. At this height level, the polluted air has the horizontal extent of about 20 degrees in longitude and latitude. The polluted air observed in Hanoi is transported further east and widely spread over the northern Pacific Ocean.