West African extreme daily precipitation in observations and stretched-grid simulations by CAM-EULAG

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2011-01-01
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Abatan, Abayomi
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William J. Gutowski Jr.
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Geological and Atmospheric Sciences

The Department of Geological and Atmospheric Sciences offers majors in three areas: Geology (traditional, environmental, or hydrogeology, for work as a surveyor or in mineral exploration), Meteorology (studies in global atmosphere, weather technology, and modeling for work as a meteorologist), and Earth Sciences (interdisciplinary mixture of geology, meteorology, and other natural sciences, with option of teacher-licensure).

History
The Department of Geology and Mining was founded in 1898. In 1902 its name changed to the Department of Geology. In 1965 its name changed to the Department of Earth Science. In 1977 its name changed to the Department of Earth Sciences. In 1989 its name changed to the Department of Geological and Atmospheric Sciences.

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1898-present

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  • Department of Geology and Mining (1898-1902)
  • Department of Geology (1902-1965)
  • Department of Earth Science (1965-1977)
  • Department of Earth Sciences (1977-1989)

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In this study, we evaluate the performance of a non-hydrostatic global climate model, CAM-EULAG (CEU), with grid stretching capability that uses NCAR Community Atmospheric Model (CAM) physics and EULAG dynamics, a non-hydrostatic parallel computational model for simulating all-scales geophysical flows developed by Smolarkiewicz and colleagues. The intent of the work is on assessing the model's utility for West African climate study. First, we evaluate its ability to simulate the climatology of West Africa with emphasis on assessing the model's capability for West African climate study. Second, we examine extreme precipitation events and their physical causes for West Africa. We compare CEU rainfall with Tropical Rainfall Measuring Mission and Global Precipitation Climatology Project precipitation, and simulated atmosphere with output from a global atmospheric reanalysis (ERA-Interim) produced by the European Centre for Medium-Range Weather Forecasts. We find that the model simulates well the mean climate over West Africa during the summer monsoon season, July-September. It reproduces the mean rainfall at the peak of the West African summer rainy season, and it captures the rainbelt associated with the ITCZ. The model simulates the core of the rainbelt consistent with the core of the deep ascent lying between the axes of the African Easterly Jet and the Tropical Easterly Jet. The model simulates fairly well the interannual and intraseasonal variability of the extreme precipitation events. Although they are not as intense as observed, the spatial scale of extreme events in the model is comparable to the observed scale. Simulated large-scale processes on extreme-event days compares well with corresponding ERA-Interim fields on observed extreme-event days. The thesis concludes with recommendations for further analysis and improvements of the model.

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Sat Jan 01 00:00:00 UTC 2011