EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Contribution of Asian emissions to upper tropospheric CO over theremote Pacific

Linda Smoydzin and Peter Hoor
Linda Smoydzin and Peter Hoor
  • Johannes-Gutenberg University, Institute for Atmospheric Physics, Germany (

By analysing the global distribution of the highest 2% of daily CO mixing ratios at 400hPa derived from the MOPITT satellite instrument for 20 years (2000-2019), we detect very regularly regions with very high CO values (i.e. mixing ratios belonging to the globally highest 2%) over the remote northern hemispheric (NH) Pacific. Such events of elevated CO over the upper tropospheric NH-Pacific occur throughout the year, with a surprisingly high regularity and frequency (70% of all days during winter, 80% respectively during spring).

During winter, most of these pollution events are detected over the north-eastern and central NH-Pacific, during spring over the central NH-Pacific and during summer over the western NH-Pacific. We detect most pollution events during spring. To link each individual pollution event detected by the 2% filtering method with a specific CO source region, we performed trajectory calculations using MPTRAC, a lagrangian transport model. To analyse transport pathways and uplift mechanisms we combine MOPITT data, the trajectory calculations and ERA-Interim reanalysis data. It becomes apparent, that air masses from China being lifted along a frontal system into the free troposphere are the major CO source throughout the year. The contribution of other source regions and uplift mechanisms shows a strong seasonal cycle: NE-Asia in relation with upward transport of air masses in the warm conveyor belt of a midlatitude cyclone is a significant CO-source region during winter, spring and summer while India is an important source region mainly during spring and summer and SE-Asia mainly during spring.

How to cite: Smoydzin, L. and Hoor, P.: Contribution of Asian emissions to upper tropospheric CO over theremote Pacific, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11050,, 2022.