TROPOSPHERIC LOW-LEVEL TEMPERATURE INVERSIONS IN THE CANADIAN ARCTIC

Climatological characteristics of the low-level tropospheric temperature inversion in the Canadian Arctic are examined using 10-40 year records of upper-air meteorological data. Inversions at the northern sites are primarily surface-based in winter, and elevated from mid-spring through summer. At the southern sites, a bimodal pattern is observed with surface-based inversions occurring during late summer, as well as during winter. From comparisons of our results with other published climatologies, it appears that this bimodal pattern reflects interactions between short- and long-wave radiation, synoptic activity and snowmelt. Maxima in inversion depth and temperature difference across the inversion layer occur in February and March; minima occur in August and September. The annual progression of inversion characteristics closely follows the annual pattern of clear-sky percentages, reflecting the controlling influence of cloud and clear-sky radiative forcings on the inversion layer.