Adjustment of observations in barometric levelling

Abstract

A barometric levelling survey may include observations with one or more portable barometers at each field station, as well as observations with several fixed barographs to monitor changes in atmospheric pressure with time. Adjustment of the observations is facilitated by transforming the set of pressures observed at each station into a set of apparent heights, and treating these as the observed quantities. By this means, heights which are already known at some stations can be incorporated in a least squares solution, which gives simultaneously the adjusted heights at all survey points, as well as a set of coefficients specifying the variation of atmospheric pressure both in time and space. Coefficients which are statistically insignificant may be automatically discarded, and a new solution found by an iterative procedure.