Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation

The Madden–Julian Oscillation (MJO) is a large-scale tropical weather system that generates heavy rainfall over the equatorial Indian and western Pacific Oceans on a 40–50 day cycle. Its circulation propagates eastward around the entire world and impacts tropical cyclone genesis, monsoon onset, and...

Full description

Bibliographic Details
Main Author: Patrick Haertel
Format: Article
Language:English
Published: MDPI AG 2022-08-01
Series:Geosciences
Subjects:
Online Access:https://www.mdpi.com/2076-3263/12/9/314
_version_ 1797487941131436032
author Patrick Haertel
author_facet Patrick Haertel
author_sort Patrick Haertel
collection DOAJ
description The Madden–Julian Oscillation (MJO) is a large-scale tropical weather system that generates heavy rainfall over the equatorial Indian and western Pacific Oceans on a 40–50 day cycle. Its circulation propagates eastward around the entire world and impacts tropical cyclone genesis, monsoon onset, and mid-latitude flooding. This study examines the mechanism of the MJO in the Lagrangian atmospheric model (LAM), which has been shown to simulate the MJO accurately, and which predicts that MJO circulations will intensify as oceans warm. The LAM MJO’s first baroclinic circulation is projected onto a Kelvin wave leaving a residual that closely resembles a Rossby wave. The contribution of each wave type to moisture and moist enthalpy budgets is assessed. While the vertical advection of moisture by the Kelvin wave accounts for most of the MJO’s precipitation, this wave also exports a large amount of dry static energy, so that in total, it reduces the column integrated moist enthalpy during periods of heavy precipitation. In contrast, the Rossby wave’s horizontal circulation builds up moisture prior to the most intense convection, and its surface wind perturbations enhance evaporation near the center of MJO convection. Surface fluxes associated with the Kelvin wave help to maintain its circulation outside of the MJO’s convectively active region.
first_indexed 2024-03-09T23:55:58Z
format Article
id doaj.art-e4cae9fc95734c55812a9f348e090e98
institution Directory Open Access Journal
issn 2076-3263
language English
last_indexed 2024-03-09T23:55:58Z
publishDate 2022-08-01
publisher MDPI AG
record_format Article
series Geosciences
spelling doaj.art-e4cae9fc95734c55812a9f348e090e982023-11-23T16:26:38ZengMDPI AGGeosciences2076-32632022-08-0112931410.3390/geosciences12090314Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian OscillationPatrick Haertel0Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, USAThe Madden–Julian Oscillation (MJO) is a large-scale tropical weather system that generates heavy rainfall over the equatorial Indian and western Pacific Oceans on a 40–50 day cycle. Its circulation propagates eastward around the entire world and impacts tropical cyclone genesis, monsoon onset, and mid-latitude flooding. This study examines the mechanism of the MJO in the Lagrangian atmospheric model (LAM), which has been shown to simulate the MJO accurately, and which predicts that MJO circulations will intensify as oceans warm. The LAM MJO’s first baroclinic circulation is projected onto a Kelvin wave leaving a residual that closely resembles a Rossby wave. The contribution of each wave type to moisture and moist enthalpy budgets is assessed. While the vertical advection of moisture by the Kelvin wave accounts for most of the MJO’s precipitation, this wave also exports a large amount of dry static energy, so that in total, it reduces the column integrated moist enthalpy during periods of heavy precipitation. In contrast, the Rossby wave’s horizontal circulation builds up moisture prior to the most intense convection, and its surface wind perturbations enhance evaporation near the center of MJO convection. Surface fluxes associated with the Kelvin wave help to maintain its circulation outside of the MJO’s convectively active region.https://www.mdpi.com/2076-3263/12/9/314Madden–Julian oscillationequatorial Rossby waveequatorial Kelvin wave
spellingShingle Patrick Haertel
Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
Geosciences
Madden–Julian oscillation
equatorial Rossby wave
equatorial Kelvin wave
title Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
title_full Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
title_fullStr Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
title_full_unstemmed Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
title_short Kelvin and Rossby Wave Contributions to the Mechanisms of the Madden–Julian Oscillation
title_sort kelvin and rossby wave contributions to the mechanisms of the madden julian oscillation
topic Madden–Julian oscillation
equatorial Rossby wave
equatorial Kelvin wave
url https://www.mdpi.com/2076-3263/12/9/314
work_keys_str_mv AT patrickhaertel kelvinandrossbywavecontributionstothemechanismsofthemaddenjulianoscillation