The climatology of air stagnation conditions over U.S. as derived from the NARR data

A 30-year (1979-2008) climatology of air stagnation conditions over conterminous U.S. is produced from the North American Regional Analysis (NARR), a long-term, high resolution, dynamically consistent meteorology dataset for North America. The air stagnation condition is determined by examining a set of variables including surface and upper-level wind speed, sea-level pressure, 500-hPa geopotential height, and low-level temperature inversion and precipitation. The high spatial resolution (32 km grid spacing) of the NARR provides a detailed distribution of air stagnation conditions across the U.S. and allows for an examination of the possible connection between the occurrence of air stagnation and local topography or urban land use. The high temporal resolution (3 hourly) enables investigation into the diurnal, monthly, and seasonal variability. Finally, the multi-decadal data set allows for an examination of the interannual variability, its possible connection to large-scale circulation indices, and linear trends over the 30-year period.