The influence of increased jet airline traffic on the amount of high level
cloudiness in Alaska

S. Nakanishi1, J. Curtis, and G. Wendler

Geophysical Institute, University of Alaska Fairbanks, Fairbanks Alaska 99775


High level cloudiness has increased over Alaska during the second half of this century, a period for which reliable data exists. This increase is most pronounced in areas close to the much-traveled routes from Europe to East Asia via Anchorage where these flights normally refuel. Seasonally, summer and spring show the greatest increases. A relative comparison with remote stations in western Alaska away from jet traffic but situated in the same climatic zone makes it likely that high cloud increase is caused by jet contrails. A relative decrease in number of clear days along the transportation corridors supports these finding in Northern Alaska, while for Interior Alaska the results were non-conclusive. Cloudiness is, of course, an important parameter for climatic change, and increased high-level cloud amount in arctic and sub-arctic areas would lead to warmer temperature; these have been observed in Alaska. See Air traffic for more details about this topic.

This study was supported by a grant to the Alaska Climate Research Center at the University of Alaska by the State of Alaska and by joint APL / DoD UPOS-ATM 7 grant.

(1) Permanent address: 3-20-14, Mihara, Asaka, Saitama, Japan,
2001, Theoretical and Applied Climatology, Vol 68(3,4), 197-205
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