Solar pulsations and angular coherence of atmospheric transparency fluctuations.
Abstract
It is noted that radial-velocity measurements in integrated sunlight are contaminated by atmospheric noise due to inhomogeneous transparency of earth's atmosphere along the line of sight to the solar disk. A measurement of the angular autocorrelation function of slow fluctuations in atmospheric transparency is described. It is shown that the typical coherence size is about 1 deg and independent of fluctuation amplitudes of 0.7 percent to 30 percent and that the angular autocorrelation function provides a link between global transparency variations and spurious measured velocities. It is concluded that all ground-based full-disk Doppler measurements should be carefully interpreted because atmospheric noise is present for periods greater than 5 min and less than about 90 min.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1979
- Bibcode:
- 1979A&A....77..347G
- Keywords:
-
- Atmospheric Effects;
- Light Transmission;
- Solar Terrestrial Interactions;
- Sunlight;
- Transparence;
- Velocity Measurement;
- Atmospherics;
- Doppler Effect;
- Earth Atmosphere;
- Radial Velocity;
- Solar Rotation;
- Solar Physics;
- Absorption:Earth Atmosphere