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Application of the NCAR regional climate model to eastern Africa2. Simulation of interannual variability of short rains

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dc.contributor.author Sun, Liqiang
dc.contributor.author Semazzi, Fredrick HM
dc.contributor.author Giorgi, Filippo
dc.contributor.author Ogallo, Laban
dc.date.accessioned 2015-08-18T08:59:31Z
dc.date.available 2015-08-18T08:59:31Z
dc.date.issued 1999-03-27
dc.identifier.citation Sun, L., Semazzi, F. H. M., Giorgi, F., & Ogallo, L. (1999). Application of the NCAR Regional Climate Model to eastern Africa: 2. Simulation of interannual variability of short rains. Journal of Geophysical Research, 104(D6), 6549. doi:10.1029/1998JD200050 en_GB
dc.identifier.uri http://www.taccire.sua.ac.tz/handle/123456789/432
dc.description.abstract We have applied the NCAR RegCM2 to the simulation of the inter-annual variability of precipitation over eastern Africa for the short-rains season by performing a set of experiments for the years 1982 to 1993. The model reproduced the observed inter-annual variability of precipitation in most of the years. The results show that remote factors play a dominant role in determining the precipitation anomalies. Inter-annual variability of precipitation over Tanzania is closely related to E1 Nifio events in their mature phase and sea surface temperature (SST) anomalies over the Indian and Atlantic Oceans. The southward shift of the Arabian High results in a southward shift of the zonal Component to f the Inter-tropical Convergence Zone (ITCZ), which is responsible for early onset of the rainy season (e.g., 1982 and 1986). The enhanced St. Helena High and weaker Mascarene High lead to the eastward shift of the meridional branch of the ITCZ for the wet years. Model simulations confirmed a strong positive correlation between precipitation anomalies over Lake Victoria and the warm E1Nifio-Southern Oscillation events, by which enhanced moist westerly flow from the Atlantic Ocean and the mainly easterly flow from the Indian Ocean converge over Lake Victoria during wet years. The inter-annual variability of precipitation over Lake Victoria and the western Kenya Highlands (WKH) are strongly coupled. Positive precipitation anomalies over the WKH region are usually associated with weaker Arabian High and Mascarene High, which weaken the large-scale divergence over the WKH region and favour the development to f convection The inter-annual variability of precipitation over eastern K enya Highlands (EKH) is not directly related to the E1 Ni fi o events, but the association with a warm SST anomaly pattern over the western Indian Ocean is evident during wet years. An E1 Ni fio signal is, however, evident for wet years over the Turkana Channel, warm SST anomalies over the northern Indian Ocean contribute enhanced water vapor transport over the region. en_GB
dc.description.sponsorship This research was supported by the NSF/ Climate Dynamics Program, project ATM-9424289. We extend our gratitude to G. Bates and C. Shields who helped in using RegCM2. M. Indeje, Y. Song, and G. Pouliot made many contributions in the work reported in this paper. We acknowledge the enlightening discussions with L. Xie, R. Burton, C. Basalirwa, A. Majugu, N. Pyuzza, G. Obua, and P. Ambenje for their help during the various stages of this work. Some of the precipitation data were obtained from the Drought Monitoring Center,N airobi, and their assistancies deeply appreciated. The model integrations were performed on the North Carolina Supercomputing Center on the T90 supercomputer The post processing of the model output was carried out at the FOA3F Visualization and Parallel Computing Facility, at North Carolina State University. FOA3F is Supported by the IBM Environmental Research Program( ERP). Any opinions, findings conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the IBM Corporation. One of the authors, LO, was supported by the START program and their support is greatly appreciated. en_GB
dc.language.iso en en_GB
dc.relation.ispartofseries ;NO. D6
dc.title Application of the NCAR regional climate model to eastern Africa2. Simulation of interannual variability of short rains en_GB
dc.type Article en_GB

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