Variations in Atmospheric Water Vapor: Baseline Results from Smithsonian Observations
Abstract
Analysis is made of midmorning measurements of absolute humidity at ground level, and spectroscopic determinations of total atmospheric precipitable water vapor above the field stations of the Astrophysical Observatory of the Smithsonian Institution (APO). The APO data used in this study cover the period 191252 and nine mountain sites (altitudes 1500 m-2711 m) in North and South America and Africa. Reported values for over 3000 days are used. Large seasonal variations are apparent, with the maximum amounts of precipitable water vapor occurring very close to midsummer at all sites. Substantial longer-term variations are also present. The observed mean amounts of precipitable water vapor for various APO sites show reasonable agreement with Kuiper's generalized predictions. Study of the relation between precipitable water vapor and surface humidity shows a strong positive correlation, but the variance is so large that surface humidity is not a reliable indicator of precipitable water vapor for any particular day. Key words: atmospheric water vapor-atmospheric extinction
- Publication:
-
Publications of the Astronomical Society of the Pacific
- Pub Date:
- December 1977
- DOI:
- 10.1086/130233
- Bibcode:
- 1977PASP...89..814R