Spole = South Pole data
SumBG = Summer background aerosol at Barrow
SprBG = Spring background aerosol at Barrow
TNB'00 = Terra Nova Bay, Antarctica
NYAspr = Spring conditions at NyAlesund, Svalbard, Norway
NYAhaze = Hazy conditions at NyAlesund, Svalbard, Norway
Haze = Haze at Barrow
Dust = Dust at Barrow
Cirrus = Cirrus clouds at Barrow

This plot shows a relationship between aerosol optical depth and Angstrom exponent at the poles, suggesting that higher aerosol optical depths are associated with larger particles. Angstrom exponent is inversely proportional to particle size. (Dust aerosol and the droplets in cirrus clouds tend to be larger than haze and background (i.e., clean conditions) aerosol.)

Data from TNB and NYA provided by V. Vitale and A. Herber, respectively.