Altitude, Elevation, and Seeing

Abstract

ABSTRACT Seeing data from 41 campaigns at 23 sites ranging in altitude from 1130 to 5150 m and elevations between 1 and 30 m above grade are used to calibrate and test a simple seeing model that only involves altitude and elevation. The model is consistent with in situ studies of optical turbulence, reproducing measured median seeing values with a dispersion of 0 $\farcs$ 096, while at multiple‐campaign sites the actual data show a dispersion of 0 $\farcs$ 092. Surface‐layer turbulence is the characteristic that varies the most between campaigns and sites and is generally the dominant contribution to seeing at low elevations, the resulting image blur decreasing with a scale height of 3.5 m. The seeing distributions are lognormal at all sites, with quartile‐to‐median ratios of 4/5 and 5/4. CR - Copyright © 2005 The University of Chicago Press