Abstract

Atmospheric blocking is an irregularly recurring anomalous state of the atmospheric circulation which is large and spatially localized. Atmospheric blocking during three unusual winter months is studied by multiresolution analysis and a new periodic wavelet-based adaptation of traditional Fourier series-based energetics. New forms of the transfer functions of kinetic energy with the mean and eddy parts of the atmospheric circulation are introduced. These quantify the zonally localized conversion of energy between scales. A new accounting method for wavelet-indexed transfers permits the introduction of a physically meaningful zonally localized scale flux function. These techniques are applied to National Meteorological Center data. Blocking is found to be largely described by just the second-largest scale part of the multiresolution analysis. New support is found for the hypothesis that blocking is partially maintained by a particular kind of upscale cascade. Specifically, in both Atlantic and Pacific blocking cases there is a downscale (upscale) cascade west (east) of the block.

Introduction

Although wavelet analysis in the time domain has been applied to atmospheric boundary layer turbulence (e.g. [8]) and climatic time series (e.g. [3, 15, 17]), and in the space domain to numerically simulated turbulence [7, 9, 18], there has not been any application to observed global synoptic meteorological data. A broad review of wavelets applied to turbulence is presented by Farge et al., this volume, Chapter 4. A collection of blocking studies is contained in [1]. During blocking, the normal progression of weather is locally inhibited.