Air Stagnation Index


A stagnation day (Wang and Angell, 1999) is when sea level geostrophic winds are less than 8 m/s (if there is a surface to 850 mb temperature inversion, then less than 10 m/s), there is no precipitation, and 500 mb wind speeds are less than 13 m/s.

April 2017 Air Stagnation Map

The Unix Compressed Data File lists the number of stagnation days in the month for each grid point of a 0.25 x 0.25 degree grid over the Lower-48 states of the USA: 201704_stag.dat.Z.