The impact of atmospheric fluctuations on degree-scale imaging of the cosmic microwave background

Fluctuations in brightness due to water vapor in the Earth's atmosphere are an important source of noise for ground-based instruments attempting to me asure the anisotropy of the cosmic microwave background. This paper present s a Kolmogorov model of atmospheric fluctuations, and derives simple expres sions to predict the impact of fluctuations on experimental measurements fo r three instrument configurations: chopped-beam, swept-beam, and interferom eter. Data from the South Pole and from the Atacama Desert in Chile, two of the driest places on Earth, are used to characterize the fluctuations at e ach site. Using an interferometric instrument as an example, the data sugge st that the South Pole is the superior site for observations of the cosmic microwave background at degree angular scales.