Date of Award

1-1-2018

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Atmospheric and Environmental Sciences

Content Description

1 online resource (ii, vii, 304 pages) : illustrations (some color), color maps.

Dissertation/Thesis Chair

Paul Roundy

Committee Members

John Molinari, Lance Bosart, Chidong Zhang

Keywords

convection, dynamics, Madden-Julian, Madden-Julian oscillation, Atmospheric circulation, Convection (Meteorology)

Subject Categories

Atmospheric Sciences

Abstract

The Madden-Julian Oscillation (MJO) is the main source of convective and circulation variability on intraseasonal timescales and planetary spatial scales within the tropics. Although the phase speed of the MJO convective envelope is often stated as 5 m s–1, MJO events that occur over the Indo-Pacific warm pool can have a range of phase speeds. This study uses a wavelet to identify MJO convective events with specified phase speeds in a satellite-derived outgoing longwave radiation (OLR) dataset during boreal winter. The wavelet-filtered OLR index is then regressed against basic meteorological variables to extract information about MJO events or signals propagating at a few phase speeds. Indeed, OLR and rainfall anomalies over most of the Indo-Pacific warm pool do tend to be most intense at phase speeds around 4 to 5 m s–1, but over the Indo-Pacific warm pool, lower amplitude events propagate at phase speeds above or below those values. In contrast, near the International Dateline, the slowest events tend to have the strongest OLR and rainfall anomalies.

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