Development of the barotropic high around Japan and its association with rossby wave-like propagations over the north pacific: Analysis of August 1984

Abstract

An observational study is made on the relationship between the development of the subtropical high around Japan and the convective activity in the northwestern tropical Pacific, and their association with wave propagations over the North Pacific during August 1984. It was found that several occasions of intensified convection around the north of the Philippines were immediately accompanied with the development of the barotropic high around Japan, and both of them were followed by eastward propagations of intensified geopotential height anomalies, at a speed of 10-12m/s, from the north of the Philippines (negative height anomaly) through over Japan (positive height anomaly) extending to the west coast of North America. These anomalies were associated with troughs and ridges of zonal wavenumber 6-7 over the North Pacific on the montly mean 500mb height field of August 1984. A comparison was made between the monthly mean 500mb height anomaly field and propagation of wave packet simulated by a linear barotropic model with a forcing around the north of the Philippines. Both of them showed quite similar patterns, suggesting that the development of the barotropic high around Japan was associated with energy propagations of barotropic Rossby wave excited by intensified convections around the north of the Philippines.