Conterminous U.S. Air Stagnation Index, Number of Days, 2007–2016

Using the National Oceanic Atmospheric Administration’s (NOAA) Air Stagnation Index (ASI), the total number of days during 2007–2016 with atmospheric conditions conducive for stagnant air conditions in the conterminous U.S. are documented in raster format geospatial data. These data provide the number of days that would allow the temporal buildup of atmospheric pollution (NOAA, 2017). NOAA provides ASI data on a monthly basis based on a modified version of Wang and Angell’s (1999) algorithm. The air stagnation index criteria are defined as sea level geostrophic wind less than 8m/sec (meters per second) (if there is a temperature inversion below 850mb (millibars), then less than 10 m/sec), 500 mb wind less than 13m/sec, and no precipitation. These criteria are evaluated at a spatial resolution of 0.25 x 0.25 degrees. The original NOAA ASI can be downloaded from the NOAA (https://www.ncdc.noaa.gov/societal-impacts/air-stagnation/).