Simultaneous measurements of atmospheric emissions at 10, 33, and 90 GHz


  • James B. Costales,

  • George F. Smoot,

  • Chris Witebsky,

  • Giovanni De Amici,

  • Scott D. Friedman


As part of a larger experiment to measure the cosmic microwave background radiation spectrum, frequent simultaneous measurements of microwave thermal emissions from the earth's atmosphere have been made at 10, 33, and 90 GHz. We have performed these measurements at two separate locations, Berkeley, California, and the White Mountain Research Station located near Bishop, California, which differ greatly in altitude and climatic conditions. Typical values of the atmospheric antenna temperature measured in Berkeley (250-m elevation) during good weather are 2.54±0.29, 12.4±0.3, and 34.3±0.5 K for 10, 33, and 90 GHz, respectively. Corresponding values measured at White Mountain (3800 m) are 1.11± 0.04, 4.48±0.18, and 11.0±0.1 K. Because the measurements are simultaneous in nature, correlations between the measurements taken at the various frequencies provide constraints on models of the microwave emission of the earth's atmosphere, especially models describing atmospheric emission as a function of precipitable water content.