Background
Boundaries between air masses or frontal zones (fronts) typically delineate boundaries between different types of vegetation, as demonstrated in the classic studies of Borchert (1950) and Bryson (1966), who, in the words of the authors, "illustrated a close concurrence between the major air masses and the biomes of eastern North America, and the correlation of frontal zones with biome transitions (ecotones)," as also described by Hare and Ritchie (1972). And "because air mass classification systems are based on many variables," they note that, typically, "small changes through time can be identified more easily than by examining, for example, only temperature (Kalkstein et al., 1998)."

What was done
In this intriguing study, Ladd and Gajewski evaluate the position of the Arctic front -- defined as "the semi-permanent, discontinuous front between the cold Arctic air mass and the intermediate Polar air mass, bounded in the south by the Polar Front (Oliver and Fairbridge, 1987)" -- based on gridded data obtained from the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis (NNR) for each July between 1948 and 2007, and from 1958 to 2002 using data from the European Centre for Medium-Range Weather Forecasts ERA-40, as well as the period 1948-1957 "for comparison with the results of Bryson (1966)."

What was learned
The two researchers report that "the position of the July Arctic front varies significantly through the period 1948-2007," but they find that it does so "with a mean position similar to that found by Bryson (1966)," which "close similarity," as they describe it, "is striking, given that the Bryson study was completed over 40 years ago."

What it means
Well if the Arctic front's mean stationarity over more than four decades is "striking", its nearly unchanged position is even more striking in light of the fact that it has moved so little over the period of time that the world's climate alarmists claim the earth warmed at a rate and to a level that was unprecedented over the past two millennia; and it is even more striking still that it has stagnated in a part of the world that is claimed by them to be warming faster than nearly all other parts of the globe. And it is even more striking still in the extreme (sorry to be running out of appropriate adjectives) for a parameter -- the location of a frontal zone -- that is supposed to be able to detect small climatic changes better than temperature itself. To borrow a musical musing from the Beatles, Very strange!

References
Borchert, J.R. 1950. The climate of the central North American Grassland. Annals of the Association of American Geographers 40: 1-22.

Bryson, R.A. 1966. Air masses, streamlines, and the boreal forest. Geographical Review 8: 228-269.

Hare, F.C. and Ritchie, J.C. 1972. The boreal bioclimates. Geographical Review 60: 333-365.

Kalkstein, L.S., Sheridan, S.C. and Graybeal, D.Y. 1998. A determination of character and frequency changes in air masses using a spatial synoptic classification. International Journal of Climatology 18: 1223-1236.

Oliver, J.E. and Fairbridge, R.W. (Eds.). 1987. The Encyclopedia of Climatology. Van Nostrand Reinhold: New York.