A54A-03
Rapid increases in tropospheric ozone production and export from China: A view from AURA and TM5

Friday, 18 December 2015: 16:30
3010 (Moscone West)
Willem W Verstraeten1, Jessica L. Neu2, Jason E Williams1, Kevin W Bowman3, John R Worden2 and Klaas Folkert Boersma4, (1)Royal Netherlands Meteorological Institute, Earth Observations, De Bilt, Netherlands, (2)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (3)Jet Propulsion Laboratory, Pasadena, CA, United States, (4)Wageningen University, Wageningen, Netherlands
Abstract:
Eastern Asia has the fastest growing anthropogenic emissions in the world, possibly affecting both the pollution in the local troposphere as well as in the trans-Pacific region. Local measurements over Asia show that tropospheric ozone (O3) has increased by 1 to 3% per year since the start of the millennium. This increase is often invoked to explain positive tropospheric O3 trends observed in western US, but to date there is no unambiguous evidence showing that enhanced Asian pollution is responsible for these trends.

In this research we use observations of tropospheric O3 from TES (Tropospheric Emission Spectrometer, onboard AURA), tropospheric NO2 measurements from OMI (Ozone Monitoring Instrument, onboard AURA) and lower stratospheric observations of O3 from MLS (Microwave Limb Sounder, onboard AURA) in combination with the TM5 CTM.

Satellite-based studies focusing on tropospheric O3 and NO2 have the potential to close the gap left by previous studies on air quality since spaceborne data provide large-scale observational evidence that both O3 precursor concentrations and tropospheric O3 levels are rapidly changing over source receptor areas.

We show the increased ability of TM5 to reproduce the 2005-2010 observed rapid rise in free tropospheric O3 of 7% over China from TES, once OMI NO2 measurements were implemented in TM5 to update NOX emissions. MLS observations on lower stratospheric O3 have the potential to improve the stratosphere-troposphere exchange (STE) estimate in TM5 which is mainly driven by ECMWF meteorological fields. Constraining the TM5 modelled trend of the STE contribution to the 3-9 km partial O3 column using MLS observations of stratospheric O3 lead to a better explanation of the sources of the free tropospheric O3 trends over China.

Based on the OMI inferred TM5 updates in NOX emissions, the impact of Asian O3 and its precursors on the free troposphere (3-9 km) over the western US could be quantified. Large import from China offsets the local efforts to improve air quality in the 3-9 km partial column over the western US with more than 40%. The issue of export and long-range transport of pollution from other countries indicates that global efforts may be required to address both the global as well as the regional air quality and climate change.

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