Correcting atmospheric path variations in millimeter wavelength very long baseline interferometry using a scanning water vapor spectrometer
Article first published online: 7 DEC 2012
Copyright 2000 by the American Geophysical Union.
Volume 35, Issue 5, pages 1241–1251, September-October 2000
How to Cite
2000), Correcting atmospheric path variations in millimeter wavelength very long baseline interferometry using a scanning water vapor spectrometer, Radio Sci., 35(5), 1241–1251, doi:10.1029/2000RS002334., and (
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 14 JUL 2000
- Manuscript Received: 11 FEB 2000
The coherence of very long baseline interferometry (VLBI) at millimeter wavelengths can be improved through the use of a water vapor radiometer (WVR) to estimate the atmospheric path length variations along the line of sight to each antenna. Measurements of the water vapor emission spectrum using a simple scanning WVR have been used to correct the interferometer phases, thereby lowering the rms phase variation and increasing the coherence time. The average improvement in the coherent fringe amplitude of 400 s VLBI scans at 3 mm wavelength was 20% with a general trend of a greater improvement for the scans with larger phase variations. Sampling of the spectrum from 18 to 26 GHz allows separation of the water vapor emission from instrumental effects and from the emission of water droplets in clouds. The observed line profiles favor the Van Vleck-Weisskopf line shape.