Model and satellite analysis of transport of Asian anthropogenic pollution to the Arctic: Siberian and Pacific pathways and their meteorological controls
Résumé
We made comprehensive analyses of long‐range transport episodes of air pollutants from East Asia to the Arctic and associated meteorological conditions. While our main focus was black carbon (BC) as its transport to the Arctic has attracted great attention, carbon monoxide (CO) was also diagnosed as a species co‐emitted with BC and as a tracer of long‐range transport. We used satellite observations by the Infrared Atmospheric Sounding Interferometer (IASI) and a newly implemented BC tagged‐tracer simulation using a global chemical transport model, GEOS‐Chem. Temporal variations of IASI‐CO column over the Pacific Arctic (160–200°E, 60–80°N) showed that episodic increases occurred several times in each season. For the period of 2007–2011, eleven strong events (6 in spring, 3 in autumn, and 2 in winter) caused by the long‐range transport from East Asia were identified. Two transport pathways from East Asia to the Arctic were found: over Siberia and the Sea of Okhotsk, and over the North Pacific. In the pathway over Siberia and the Sea of Okhotsk, the pollutants were transported northeastward from China mainly through the Sea of Okhotsk and East Siberia. The low pressures passing from East Siberia to the Sea of Okhotsk played important roles in the transport in the lower troposphere and uplifting to the middle troposphere. In the pathway over the North Pacific, the pollutants were transported eastward from the Asian continent and subsequent northward transport took place over the North Pacific. The poleward transport occurred west of the high pressure that stayed around the Bering Sea.
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