An Objective Technique for Separating Macroscale and Mesoscale Features in Meteorological Data

Abstract

An objective technique for quantitative scale separation has been developed to study atmospheric circulations associated with large complexes of thunderstorms. The scheme utilizes two separate low-pass filter analyses of the same data set to extract mesoscale and macroscale signals. An objective analysis of the total meteorological field (with microscale variations suppressed) is recovered as the sum of the mesoscale and macroscale components. Case study examples demonstrate that the technique is indeed useful for studying mesoscale convective systems. It is shown that convectively forced mesoscale circulations may significantly perturb the environmental flow on scales large enough to be detected in synoptic upper air data. The case studies also suggest that the analysis routines could be utilized in operational forecasting applications.