An Experiment in Objective Analysis

An experiment in two-dimensional objective analysis, conducted at The Institute for Advanced Study is described. The method consists of fitting a second degree polynomial by the method of least squares to the meteorological data in a limited area around each point in a rectangular grid, and then interpolating for the height of the pressure surface at the grid point. The results of machine computations give analyses which are comparable in quality to the subjective analyses ordinarily encountered. When used in a three-parameter atmospheric model for a numerical forecast, the objective analyses led to a more accurate forecast than carefully prepared subjective analyses did. Also a satisfactory representation of the field of vertical stability (over North America) was obtained by the two-dimensional analyses, made for three different pressure surfaces.

The greatest obstacle encountered in producing a completely objective analysis arises from errors of computation and transmission of raw meteorological data. This obstacle has not been overcome, and necessitates a preliminary subjective examination of the data for detection of errors.