Origins of Air Masses over an Alaskan Glacier and Implications for Ice Core Studies in the North Pacific Region

概要

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Simulations of 10-day backward trajectories of air masses from Mount Wrangell, an Alaskan ice core site, were calculated for 11 years on a daily basis. Results were analyzed statistically in order to interpret monthly air mass contributions over the ice core site and to discuss implications for ice core studies in the North Pacific Region (NPR). Increases in tropospheric air mass transport from EA in spring suggest favorable transport conditions for Asian dust during this season. The stratospheric air mass (< 300 hPa) over the ice core site increases in winter and that from East Asia (EA) to the North Pacific Ocean in late spring. The tritium peaks observed in the ice core in late spring were discussed in the context of the present results with two possibilities on the time lag of tritium transportation in the stratosphere and the seasonal variations of water vapor amount in the troposphere. Increases in air masses originating from Siberia, Alaska and Canada in summer-fall favor the transport of black carbon due to forest fires over the ice core site. These results allow advanced interpretation of the origin and transport processes of materials in the ice core proxies in the NPR.