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Seasonal, synoptic, and intraseasonal variability of the West African monsoon

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dc.contributor.authorMcCrary, Rachel Rose, author
dc.contributor.authorRandall, David A., advisor
dc.contributor.authorDenning, A. Scott, committee member
dc.contributor.authorvan den Heever, Susan C., committee member
dc.contributor.authorBetsill, Michele, committee member
dc.date.accessioned2007-01-03T05:36:08Z
dc.date.available2007-01-03T05:36:08Z
dc.date.issued2012
dc.description.abstractThe simulation of the West African monsoon is examined in two coupled general circulation models (CGCMs). The first model is the standard Community Climate System Model (CCSM) which uses traditional parameterizations to represent convective processes. The second model is the superparameterized-CCSM (SP-CCSM), in which convective parameterizations have been replaced by embedding a two-dimensional cloud resolving model into each gridbox. Superparameterization is intended to improve simulation of the complex multiscale interactions that occur between the large-scale environment and clouds. Key features of West African climate are analyzed in both models including: the mean annual cycle of the monsoon, African easterly wave (AEW) activity and dynamics, and the intraseasonal modulation of precipitation. Adding superparameterization improves the position and intensity of the summer maximum in precipitation which is shifted from over the Gulf of Guinea in CCSM (not realistic), to over the continent in SP-CCSM which is in keeping with the observations. AEWs and their relationship with convection are also improved in the SP-CCSM: In the standard model, little to no easterly wave activity occurs over West Africa, and the relationship with convection is tenuous at best. SP-CCSM on the other hand produces strong AEWs over the region that exhibit similar horizontal and vertical structures to observations. AEWs in SP-CCSM are strongly coupled to convection, more so than is supported by observations. An examination of the energetics of the simulated AEWs suggests that convection drives the generation and propagation the waves in SP- CCSM. Consistent with observations, intraseasonal variations in West African precipitation in SP-CCSM appear to be linked to variations in convection in the Indo-Pacific region corresponding with the MJO and the Indian monsoon. Because of these physically-realistic relationships, SP-CCSM has potential to deepen our understanding of the teleconnections between the MJO and West Africa, helping to improve seasonal rainfall forecasts.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierMcCrary_colostate_0053A_11409_opt.pdf
dc.identifier.urihttp://hdl.handle.net/10217/79444
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectmonsoon
dc.subjectclimate models
dc.subjectclimate
dc.subject.lcshAfrica
dc.titleSeasonal, synoptic, and intraseasonal variability of the West African monsoon
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineAtmospheric Science
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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