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Simulation of tropical tropospheric ozone variation from 1982 to 2010: The meteorological impact of two types of ENSO event
Author(s) -
Hou Xuewei,
Zhu Bin,
Fei Dongdong,
Zhu Xiaoxin,
Kang Hanqing,
Wang Dongdong
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd024945
Subject(s) - troposphere , atmospheric sciences , tropospheric ozone , anomaly (physics) , climatology , ozone , walker circulation , el niño southern oscillation , chemical transport model , environmental science , geology , physics , meteorology , condensed matter physics
The effects of two types of ENSO events on tropical ozone (O 3 ) variations from 1982 to 2010, and the mechanisms underlying these effects, were analyzed using observations and model simulations. Tropospheric column O 3 anomalies (TCOA) during canonical El Niño were different from El Niño Modoki. Absolute TCOA values are larger during canonical El Niño than during El Niño Modoki in most regions. La Niña events were not separated into the different types because of their similarity in terms of sea surface temperature patterns. TCOA in La Niña showed a reversed dipole from canonical El Niño. During canonical El Niño, anomalous downward motion together with suppressed convection weakened O 3 outflow from the troposphere, causing an increase in tropospheric O 3 over western Pacific. Over central and eastern Pacific, decreased O 3 concentrations resulted primarily from a change in net chemical production of O 3 . The change in net O 3 chemical production relates to increased levels of HOx under wetter condition. During El Niño Modoki, transport and chemical fluxes were similar but weaker than during canonical El Niño. During La Niña, O 3 anomalies and transport fluxes were the opposite of those during the El Niño Modoki. Stratospheric O 3 played a key role in the development of O 3 anomaly above 250 hPa during ENSO events, contributing >30% to the O 3 anomalies. The change in free tropospheric O 3 affected the O 3 anomaly from 850 hPa to 200 hPa (60% of O 3 anomaly). The contribution of O 3 from planetary boundary layer was concentrated at the surface, with a contribution of <15%.