Comments on “Detection of Climatic Change in the Western North American Arctic Using a Synoptic Climatological Approach”

Abstract

Analyses of records from four stations in interior Yukon and adjacent Alaska concerning changes in synoptic conditions during winter indicate since the late 1940s 1) decreasing frequency of coldest air masses, 2) increasing frequency of mild air masses, and 3) warming of the coldest synoptic types. The stations used in the analyses are in valleys. The frequency analyses refer to the cumulative portion of winter when particular synoptic conditions are experienced at each site. The discussion suggests that since the lowest air temperatures are associated with topographically enhanced inversions, persistence of stable conditions may be required to generate the coldest air temperatures. As a result, the data leading to conclusion 3 may be a product of the changing airmass frequencies with cold air masses displaced more often. Upper-air observations or data from stations in upland locations may not exhibit such effects to the same extent.