Stagnation Index

Definition of a stagnation day
	The stagnation index was formulated by Wang, J.X.L., and J.K. Angell, 1999: Air Stagnation Climatology for the United States (1948-1998). NOAA/Air Resources Laboratory ATLAS, No.1 (Available at www.arl.noaa.gov/pubs/online/atlas.pdf)
	Criteria for a stagnation day are:
a)	Sea level geostrophic winds less than 8 ms-1 (this corresponds to an anemometer observed wind of approximately 4 ms-1)
b)	If there is a surface to 850mb temperature inversion then this geostrophic wind criterion is relaxed to less than 10 ms-1.
c)	No precipitation
d)	500mb wind speeds less than 13 ms-1

The files in this directory are lists of 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.

Uploaded by Trevor Wallis