Abstract
In ten years of 1994 to 2003, January air transports in the Hokkaido, Kanto, and Kyushu regions were analyzed calculating 7day backward air parcel trajectories with the meteorological wind analysis data set (NCEP-DOE AMIP-II Reanalysis). As a new result, an anomalous air parcel route was found out over the Hokkaido region: In January climatology as has been well-known so far, air parcels transported from the Eurasian continent sweep out the entire Japan Islands. In several years interval, however, only the Hokkaido region happens to be invaded by air parcels moving westwards from the Kamchatka Peninsula, although this route is not seen in the other Januarys.
