The NOAA Barrow Atmospheric Baseline Observatory (Figure 1) was established in 1973 and has been in continuous operation since that date. Starting with a few basic parameters, the manned observatory today conducts upwards of 200 measurements and supports a dozen cooperative programs from universities and other federal agencies. In March-April of 1983, 1986, 1989 and 1992, a NOAA WP-3D equipped with gas and aerosol instruments similar to those in operation at the observatory was flown upwind and in profiles above the observatory to put the ground based measurements into context.

Although Barrow is located in a tundra region of low primary productivity, carbon dioxide measurements over the past decades show that the Alaskan Arctic exhibits one of the largest annual carbon dioxide cycles observed on earth. The sharp summer carbon dioxide drawdown is due to growth of vegetation in the large boreal forests at lower latitudes in Canada and Russia then transported north. The fall and winter rebounds, that successively top out a bit higher than the previous year, are the result of the accumulation of carbon dioxide from fossil fuel combustion at lower latitudes also transported northward. A global carbon dioxide distribution "carpet" showing the Barrow measurements in red is presented in Figure 2.

The long-term Barrow aerosol light scattering record (Figure 3) is a measure of the number and size of the aerosol particles in the air flowing past the observatory. There is a pronounced annul cycle in aerosol concentrations measured at the surface (Figure 3, upper right inset graph) with the largest light scattering observed in the late winter-early spring "Arctic Haze" season. This haze is primarily air pollution from Eastern Europe and Russia flowing into the Atlantic side of the Arctic with occasional aerosol inputs from Asia that have crossed the Pacific Ocean and entered the Alaskan Arctic from the west. The low aerosol concentrations at Barrow in the summer are due to both reduced transport to the Arctic in summer months and a persistent cloud layer in summer that removes aerosol in the marine boundary layer.

There is variability in the concentrations of Arctic Haze as may be observed in the light scattering records for March and April, 1977-2007 (Figure 3, lower left) that show the amount of aerosol at Barrow was low in 1980 rising to its highest level in 1982 and then generally decreasing through to 2007. These trends are thought to reflect changing atmospheric transport into the Arctic coupled with lower emissions of air pollution in present day Russia.

Aerosol distributions and concentrations in a WP-3D profile above and upwind of the Barrow Observatory, March 1983, are presented in Figure 4. In this figure it may be observed that there are 6 distinct layers of Arctic Haze flowing across Barrow.