Phase locking between atmospheric convectively coupled equatorial Kelvin waves and the diurnal cycle of precipitation over the Maritime Continent

Photo courtesy UCAR

Photo courtesy UCAR

TitlePhase locking between atmospheric convectively coupled equatorial Kelvin waves and the diurnal cycle of precipitation over the Maritime Continent
Publication TypeJournal Article
Year of Publication2016
AuthorsBaranowski D.B, Flatau M.K, Flatau P.J, Matthews A.J
JournalGeophysical Research Letters
Volume43
Pagination8269-8276
Date Published2016/08
Type of ArticleArticle
ISBN Number0094-8276
Accession NumberWOS:000383290300056
KeywordsContinent; convectively coupled equatorial waves; diurnal cycle; madden-julian oscillation; Madden-Julian oscillations; maritime; ocean; rainfall
Abstract

Convectively coupled Kelvin waves (CCKWs) are a major component of the tropical atmospheric circulation, propagating eastward around the equatorial belt. Here we show that there are scale interactions between CCKWs and the diurnal cycle over the Maritime Continent. In particular, CCKW packets that pass a base point in the eastern Indian Ocean at 90 degrees E between 0600 and 0900UTC subsequently arrive over Sumatra in phase with the diurnal cycle of convection. As the distance between Sumatra and Borneo is equal to the distance traveled by a CCKW in 1day, these waves are then also in phase with the diurnal cycle over Borneo. Consequently, this subset of CCKWs has a precipitation signal up to a factor of 3 larger than CCKWs that arrive at other times of the day and a 40% greater chance of successfully traversing the Maritime Continent.

DOI10.1002/2016gl069602
Impact: 

We have shown a systematic impact on CCKWs over the Maritime Continent that depends on the time of day of their arrival. CCKWs that pass a base point over the Indian Ocean at 90°E are in phase with the diurnal cycle over Sumatra and Borneo. Compared with CCKWs that arrive 6 h earlier, these favored waves have a precipitation signal that is up to 3 times larger, and they are 40% more likely to successfully traverse the Maritime Continent. These scale interactions between the diurnal cycle and CCKWs are an example of rectification in the climate system.

Student Publication: 
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