Infilled daily air temperature data for D1 chart recorder, 1952 - ongoing.

Daily minimum and maximum surface air temperature data have been
collected at the D1 climate station (3739 m asl) almost continuously
from 1952 to the present. D1 is on a narrow, exposed ridge on the
westernmost part of Niwot Ridge, 2.6 km east of and ca. 200 m lower
in elevation than the Continental Divide. Surrounding vegetation is
low-stature alpine tundra. Temperature minima and maxima were
measured with a chart-recording hygrothermograph housed in a
Stevenson screen. Hygrothermograph records were calibrated at the
time of chart changes against liquid-in-glass thermometers.
Processing included quality checks and infilling of missing daily
data (see Methods).