Temperature dependence of absorption in ice at 532 nm

A YAG laser was used to emit nanosecond pulses of light at 532 nm at depths from 1185 to 2200 m in Antarctic ice, corresponding to temperatures increasing from 229 to 249 K. From the timing distributions of photons arriving at phototubes at distances up to 100 m and at similar depths, the scattering and absorption coefficients were measured, and the temperature dependence of absorptivity at 532 nn was determined. Despite the absorptivity being many orders of magnitude lower at 532 nm than in the near ultraviolet and near infrared. the fractional increase of absorptivity, a(-1) da/dT = 0.01 K-1, was the same in the visible, ultraviolet, and infrared. Analysis of published data at other wavelengths shows that a(-1)da/dT is similar to0.01 K-1 from 175 nm to similar to1 cm, above which it increases strongly from 1 cm to 10 m. That temperature dependence applies only in regions not close to absorption bands. (C) 2001 Optical Society of America.