Estimation of atmospheric predictability by circulation analogs

Abstract

An empirical predictability study is presented based on 700-hPa Northern Hemispheric circulation analogs. A linear relationship between the initial root-mean-square difference of analog pairs and the time taken for the error to reach a certain limit value is used to extrapolate the predictability with initial errors considerably smaller than those in the present database. The relationship, first used in predictability experiments with the NMC numerical weather prediction (NWP) model, conforms to the experimental data in that the error growth depends not only on the magnitude of the error but also, to a lesser extent, on the initial error. -from Author