This study uses a non-traditional method to substantiate the underlying influence of the parameterization of subgrid-scale convective processes on the capability of the latest generation of global climate models to simulate the seasonal cycle of rainfall associated with the West African monsoon and establish a direct connection between the treatment of convective rainfall and overall model performance on seasonal time scales. To establish the degree to which convective parameterizations may influence model simulations at seasonal scales more definitively, a single column of grid-scale output was extract from an emissions scenario experiment for two coupled models and compared to the observed evolution of rainfall, surface meteorology, the thermodynamic state of the atmosphere, clouds and radiation, obtained during 2006 in Niamey, Niger. Overall both models demonstrated a remarkable capability to comprehensively capture the seasonal cycle of the West African monsoon in the vicinity of Niamey. However, the results confirm that deficiencies in subgrid-scale physics can be a significant source of error with regards to the timing of simulated rainfall at seasonal scales and, in some models dominate non-local sources of error. Comparison of the performance of each model and their respective convective parameterizations indicated that the capability to simulate the seasonal cycle of rainfall in the Sahel with realistic timing appears to be more sensitive to a realistic representation of convective precipitation microphysics than to a realistic representation of the organization of convective structures. The perspective gained from this study sheds a more positive light on the present capabilities of coupled models to simulate convection in the Sahel and suggests that resolution of the long-standing disagreement in rainfall projections among different coupled models may be more within reach than previously advocated by performance evaluations based on traditional methods.
Subject (authority = RUETD)
Topic
Atmospheric Science
Subject (authority = ETD-LCSH)
Topic
Climatology--Mathematical models
Subject (authority = ETD-LCSH)
Topic
Climatic changes--Africa, West
Subject (authority = ETD-LCSH)
Topic
Rain and rainfall--Africa, West
RelatedItem (type = host)
TitleInfo
Title
Rutgers University Electronic Theses and Dissertations
Identifier (type = RULIB)
ETD
Identifier
ETD_7524
PhysicalDescription
Form (authority = gmd)
electronic resource
InternetMediaType
application/pdf
InternetMediaType
text/xml
Extent
1 online resource (xvii, 116 p. : ill.)
Note (type = degree)
Ph.D.
Note (type = bibliography)
Includes bibliographical references
Note (type = statement of responsibility)
by Lynne C. Trabachino
RelatedItem (type = host)
TitleInfo
Title
Graduate School - New Brunswick Electronic Theses and Dissertations
Identifier (type = local)
rucore19991600001
Location
PhysicalLocation (authority = marcorg); (displayLabel = Rutgers, The State University of New Jersey)
Rutgers University. Graduate School - New Brunswick
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Type
License
Name
Author Agreement License
Detail
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